Document:

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                                                                   EXHIBIT 10.6

                               AGREEMENT OF LEASE

                                     BETWEEN

                            JOSHUA REALTY CORPORATION

                                       AND

                        AMERICAN MANAGEMENT SYSTEMS, INC.

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                               AGREEMENT OF LEASE
                              CENTERPOINTE I AND II
                                FAIRFAX, VIRGINIA

                                TABLE OF CONTENTS

1. Reference Data and Definitions............................................1
2. Demise of Premises........................................................4
3. Term......................................................................4
4. Possession................................................................5
5. Use of the Premises.......................................................6
6. Base Rent.................................................................6
7. Additional Rent...........................................................7
8. Late Charge; Interest....................................................14
9. Services.................................................................14
10. Repairs and Condition of Premises.......................................19
11. Compliance with Law.....................................................19
12. Estoppel Certificate....................................................20
13. Rules and Regulations...................................................21
14. Assignment and Subletting...............................................21
15. Alterations.............................................................24
16. Mechanics' and Other Liens..............................................25
17. Landlord's Right to Enter...............................................26
18. Certain Rights Reserved by Landlord.....................................26
19. Landlord's Liability; Rights............................................28
20. Unilateral Amendment....................................................29
21. Insurance...............................................................29
22. Fire or Other Casualty..................................................30
23. Waiver of Claims; Indemnification.......................................32
24. Condemnation............................................................33
25. Holding Over............................................................33
26. Covenant of Quiet Enjoyment.............................................34
27. Relocation of Tenant.  Intentionally Omitted............................34
28. Condition of Premises...................................................34
29. No Third Party Beneficiaries............................................34
30. Transfer of Landlord's Interest.........................................35
31. Default; Landlord's Remedies............................................35
32. Remedies Cumulative.....................................................38
33. Expenses of Enforcement.................................................38
34. Nonwaiver...............................................................38
35. Subordination...........................................................38
36. Paramount Lease.........................................................39
37. Legal Proceedings. .....................................................40
38. Interpretation..........................................................40
39. Severability............................................................40

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40. Notices.................................................................40
41. No Representation by Landlord...........................................41
42. Whole Agreement.........................................................41
43. Security Deposit.  Intentionally Omitted................................41
44. Real Estate Broker......................................................41
45. Inability to Perform....................................................41
46. Corporate Entities......................................................42
47. Recordation.............................................................42
48. Time....................................................................42
49. Applicable Law..........................................................42
50. Defined Terms...........................................................42
51. Delivery for Examination................................................44
52. Environmental Matters...................................................44
53. Tenant's Remedies.......................................................46
54. Extension Option........................................................47
55. Signage.................................................................49
56. Storage Space...........................................................49
57. Food Service In Centerpointe II Building................................50
58. Non-Disturbance.........................................................50
59. Exercise Room...........................................................51
60. Parking.................................................................51
61. Right of First Offer....................................................51
62. Expansion Space.........................................................53
63. Measurement of Premises. Intentionally Omitted..........................54
64. Tenant's Affiliation Representation.....................................54
65. Arbitration.............................................................54

        Exhibit A-1.                 Plan of Centerpointe I Premises
        Exhibit A-2.                 Plan of Centerpointe II Premises
        Exhibit B.                   Landlord's Base Building Modifications
        Exhibit C                    Tenant Design and Construction Process
        Exhibit D                    Concession Fund Voucher Form
        Exhibit F                    Rules and Regulations
        Exhibit G                    HVAC Standards
        Exhibit H                    Legal Description of the Property
        Exhibit I                    Index of Defined Term
        Exhibit J.                   Form of Lease Memorandum

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                               AGREEMENT OF LEASE
                              CENTERPOINTE I AND II
                                FAIRFAX, VIRGINIA

         This Lease is made this 10th day of August, 1992, between JOSHUA REALTY
CORPORATION, a Delaware corporation, (general partner and sole remaining partner
of Faircenter Limited Partnership, a Delaware limited partnership)(hereinafter
referred to as "Landlord"), and AMERICAN MANAGEMENT SYSTEMS, INC., a Delaware
corporation, (hereinafter referred to as "Tenant").

         1.        REFERENCE DATA AND DEFINITIONS:

         ANY REFERENCE IN THIS LEASE TO THE FOLLOWING SUBJECTS SHALL INCORPORATE
THEREIN THE DATA STATED FOR THE SUBJECTS IN THIS ARTICLE 1.

                   1.1.    DEMISED PREMISES

                   (a)     SPACE DESCRIPTION - CENTERPOINTE I: Approximately
                           203,630 rentable square feet on eleven (11) floors of
                           the building ("Centerpointe I Building") located at
                           4050 Legato Road, Fairfax, Virginia and commonly
                           known as Centerpointe I (the "Centerpointe I
                           Premises") as shown on Exhibit "A-l" attached hereto.

                   (b)     SPACE DESCRIPTION - CENTERPOINTE II: Approximately
                           38,384 rentable square feet of space on the third
                           (3rd) and fourth (4th) floors of the building
                           ("Centerpointe II Building") located at 4000 Legato
                           Road, Fairfax, Virginia and commonly known as
                           Centerpointe II (the "Centerpointe II Premises") as
                           shown on Exhibit "A-2" attached hereto.

                   (c)     RENTABLE AREA OF THE DEMISED PROMISES: The
                           Centerpointe I Premises and the Centerpointe II
                           Premises are herein together defined as the
                           "Premises" and the Centerpointe I Building and the
                           Centerpointe II Building are herein together defined
                           as the "Buildings". The exact square footage of the
                           Premises has been measured in accordance with the
                           Washington, D.C. Association of Realtor's Standard
                           Method of Measurement (January 1, 1989). This figure
                           shall be used for all purposes under this Lease,
                           including, but not limited to, determination of Base
                           Rent and Additional Rent.

                   1.2.    Base Rent: Thirteen Dollars and Seventy Cents
($13.70) per rentable square foot, net of Electricity Costs (as defined in
Article 7.1.3), and subject to adjustment as described in Article 6.3 below.

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                   1.3.1.  BASE YEAR OPERATING EXPENSES shall mean the Operating
Expenses (as defined in Article 7 below) incurred by Landlord during the
calendar year 1993, as adjusted pursuant to Article 7.4.4 below.

                   1.3.2.  BASE YEAR REAL ESTATE TAXES shall mean the Real
Estate Taxes (as defined in Article 7 below) incurred by Landlord during
calendar year 1993 (as the same may be adjusted pursuant to Article 7.1.1(e)
below).

                   1.4.    RENT COMMENCEMENT SCHEDULE: Tenant shall commence
Base Rent payments for the Premises in accordance with the schedule below.

                    Rent
                    Commencement Date                 RSF
                    -----------------                 ---

                    (a)  December 1, 1992             70,451
                    (b)  May 1, 1993                  38,336
                    (c)  August 1, 1993               38,336
                    (d)  November 1, 1993             38,384
                    (e)  May 1, 1994                  56,507

                   The space described in Article 1.4(a) above is herein defined
as the "Initial Space" and the space described in Article 1.4(b)-1.4(e) is
herein defined as the "Subsequent Space". The dates in Articles 1.4(b)-1.4(e)
under the column "Rent Commencement Date" are each herein defined as a
"Scheduled Rent Commencement Date".

                   1.5.    CONCESSION FUND:  $28.50 per rentable square foot.

                   1.6.    SECURITY DEPOSIT:   None

                   1.7.    STANDARD BUILDING OPERATING DAYS AND HOURS:

                           (a)       Centerpointe I Building:

                           8:00 A.M. to 7:00 P.M. Monday - Friday
                           8:00 A.M. to 1:00 P.M. Saturday

                           (b)       Centerpointe II Building:

                           8:00 A.M. to 6:00 P.M. Monday - Friday
                           8:00 A.M. to 1:00 P.M. Saturday

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                   1.8.    PERMITTED USE: General office use, and uses
incidental thereto (including, without limitation, the conduct of computer
operations and the use and operation of all equipment related thereto).

                   1.9     (a)     ADDRESS FOR NOTICES TO TENANT:

                                   American Management Systems, Inc.
                                   1525 Wilson Boulevard Suite 130
                                   Arlington, Virginia 22209
                                   Attn: Mr. Thomas W. Huba

                                   with copies of notices at all times to:

                                   Shaw, Pittman, Potts & Trowbridge
                                   2300 N Street N.W.
                                   Washington, D.C. 20037
                                   Attn: Craig A. deRidder, Esquire

                           (b)     ADDRESS FOR NOTICES TO LANDLORD PRIOR TO
                                   LEASE COMMENCEMENT DATE:

                                   Joshua Realty Corporation
                                   c/o LPC Commercial Services, Inc.
                                   4050 Legato Road
                                   Fairfax, Virginia 22030
                                   Attn: Mr. Michael Taylor

                                   Address from and after Lease Commencement
                                   Date:

                                   c/o LPC Commercial Services, Inc.
                                   4000 Legato Road
                                   Suite 950
                                   Fairfax, Virginia 22030
                                   Attn: Mr. Michael Taylor

                                   with copies of notices at all times to:

                                   Lincoln Property Company
                                   1530 Wilson Boulevard, Suite 200
                                   Arlington, Virginia 22209

                                   Attention: Mr. John B. Grissim

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                                   and

                                   General Electric Investment Corporation
                                   3003 Summer Street
                                   Stamford, Connecticut 06904-7900

                                   Attention: Mr. Steven D. Burton

                                   and

                                   Wolf, Block, Schorr and Solis-Cohen
                                   12th Floor Packard Building
                                   15th and Chestnut Streets
                                   Philadelphia, PA 19102

                                   Attention: Alvin H. Dorsky, Esquire

         2.        Demise of Premises. Landlord hereby leases to Tenant, and
Tenant hereby hires and takes from Landlord, the premises identified as the
"Premises", for the Term (defined below) and subject to the covenants, terms,
provisions and conditions of this Lease, together with the right to use, in
common with others, of all common and public areas in the Buildings including
(without limitation) elevators, stairways, lobbies and corridors in the
Buildings necessary for access to the Premises (provided, however, that subject
to Landlord's right to entry hereunder, use of the common areas of the
Centerpointe I Building shall be consistent with that afforded to a single
tenant building during the time that Tenant is leasing one hundred percent
(100%) of the rentable area of the Centerpointe I Building).

         3.        Term.

                   3.1.    The term (the "Term") shall commence on the date of
this Lease (the "Lease Commencement Date") and shall end, without the necessity
of notice from either party to the other, on November 30, 2007 ("Termination
Date").

                   3.2.    The Term shall commence as to each segment of the
Subsequent Space on the earlier of (i) the date which is four (4) months prior
to the respective Scheduled Rent Commencement Date for such segment of the
Subsequent Space or (ii) the date that Tenant or anyone claiming under or
through Tenant first occupies such segment of the Subsequent Space (each such
date which is the earlier of (i) or (ii) above is herein defined as a
"Subsequent Lease Commencement Date").

                   3.2.1.  Tenant's obligation to pay Rent (defined in Article
1.2) for the Initial Space shall commence on December 1, 1992 ("Rent
Commencement Date"). All other obligations of Tenant pertaining to the initial
Space under this Lease shall commence on the Lease Commencement Date.

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                   3.2.2.  Tenant's obligation to pay Rent for any segment of
the Subsequent Space shall commence on the Scheduled Rent Commencement Date for
such segment of the Subsequent Space (each such date is herein defined as a
"Subsequent Rent Commencement Date"). If Tenant occupies any segment of
Subsequent Space for the Permitted Use prior to the Subsequent Rent Commencement
Date for that segment of Subsequent Space, then Tenant shall pay to Landlord an
amount equal to Five Dollars ($5.00) per rentable square foot per annum, in
equal monthly installments in advance, as Additional Rent hereunder for each
such segment of Subsequent Space from and after the date that Tenant occupies
and uses that segment of Subsequent Space for the Permitted Use until the
Subsequent Rent Commencement Date for that segment of Subsequent Space. All
other obligations of Tenant pertaining to each segment of the Subsequent Space
under this Lease shall commence on the respective Subsequent Lease Commencement
Date.

                   3.3.    The First Lease Year shall be the period commencing
on the Rent Commencement Date and continuing through December 31, 1993. Each
Lease Year after the First Lease Year shall be a consecutive twelve (12) month
period commencing on the first day of the calendar month immediately following
the preceding Lease Year, except that the Last Lease Year shall be the period
from the first day of Tenant's partial Lease Year occurring at the end of the
Term until the Termination Date.

         4.        Possession.

                   4.1.    In addition, to the extent required by law, Landlord
will comply with the requirements of the Americans With Disabilities Act of 1990
("ADA") requirements applicable to the "Core Elements" of the Buildings
(including those which may arise because of the performance of the Tenant Work)
and Tenant shall comply with all other ADA requirements respecting the Premises,
including those requirements arising from Tenant Work. The "Core Elements" of
the Buildings are defined as the roof, the ground floor lobby or lobbies,
entryways, the garage, surface parking areas, paths of travel to and from the
Buildings, loading docks and loading zones, elevators and elevator call buttons,
stairways, risers and other penetrations, restrooms and drinking fountains not
installed by Tenant in connection with the Tenant Work, or otherwise, and the
base-building mechanical, electrical, HVAC and plumbing systems (excluding any
changes thereto or extensions thereof performed as part of the Tenant Work or
any later Tenant alteration).

                   4.2.    "Tenant Work" as used in this Lease shall mean the
provision of the materials, components, labor and services encompassed within
the work described in the Tenant Design and Construction Process (as defined in
Exhibit "C"). Landlord shall provide a concession fund equal to Twenty-Eight
Dollars and Fifty Cents ($28.50) per rentable square foot ("Concession Fund").
The Concession Fund may be utilized to pay the cost of construction, demolition,
construction documentation and associated permits and fees, architectural and
engineering fees, moving expenses and other reasonable move-related expenses,
signage, Tenant's legal fees incurred in negotiations of this Lease, remaining
lease liability coverage and holdover penalties and furniture and equipment. The
Concession Fund shall be applied to the items described above in such amounts as
Tenant may determine, and disbursed by Landlord from time to time to Tenant, so
long as Tenant is not in default (which term for purposes of this Article 4.2

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shall not be deemed to be a circumstance entitled to the benefit of notice and
cure periods provided under Article 31 below) under this Lease, pursuant to the
Concession Fund Voucher Form attached hereto as Exhibit "D". Tenant covenants
that Tenant shall utilize a minimum of fifty percent (50%) of the Concession
Fund for direct hard cost improvements to the Premises. For purposes hereof, the
term "hard costs" shall mean all costs incurred by Tenant in the design,
engineering and construction of leasehold improvements in the Premises,
including all contractor and materialman charges. in no event shall Landlord
have any obligation to pay for costs relating to Tenant Work or for any of the
other items for which the Concession Fund may be utilized in an amount that
exceeds the Concession Fund. A reconciliation to establish that the requisite
portion of the Concession Fund has been expended for hard costs of improvements
to the Premises shall be submitted to Landlord by Tenant within sixty (60) days
after the completion of the Tenant Work. So long as Tenant has expended the
requisite portion of the Concession Fund on hard costs and Tenant is not in
default (which term for purposes of this Article 4.2 shall not be deemed to be a
circumstance entitled to the benefit of notice and cure periods provided under
Article 31 below) under this Lease, the portion of the Concession Fund not
disbursed to Tenant by the date of reconciliation referred to above shall be
credited against the Monthly Installments of Base Rent payable hereunder as
follows: (i) an amount up to $5.00 per rentable square foot shall be credited
against the next installments) of Base Rent payable hereunder and (ii) any
amount in excess of $5.00 per rentable square foot shall, after the credit
described in the immediately preceding clause has been exhausted, be credited in
twelve equal installments against the next twelve Monthly Installments of Base
Rent.

                   4.3.    Landlord and Tenant recognize and agree that floors
1, 7, 8 and 10 of the Centerpointe I Building constitute the Initial Space, that
the County of Fairfax ("County") has vacated the Initial Space and that Landlord
has made the Initial Space available to Tenant for Tenant Work on the date
hereof. Except for the 4th floor of the Centerpointe II Building, which shall be
used by the County for storage until February 28, 1993, Landlord shall make the
Subsequent Space available for possession by Tenant no later than December 31,
1992. If for any reason Landlord is unable to so deliver the Subsequent Space,
Landlord agrees to pay to Tenant, as Tenant's sole remedy for Landlord's
inability to deliver the Subsequent Space as aforesaid (as reimbursement for the
actual holdover penalty that Tenant will incur under its present lease for
premises located at 1525 Wilson Boulevard, Arlington, Virginia) (the "Wilson
Boulevard Lease"), an amount up to $75,000 per month, to be pro rated on a per
them basis if permitted under the Wilson Boulevard Lease (the "Holdover
Payment") and to the extent that such failure to deliver any segment of the
Subsequent Space causes Tenant to have less than 120 days to complete the Tenant
Work for any segment of the Subsequent Space, the Subsequent Rent Commencement
Date for such segment(s) of the Subsequent Space shall be extended by the number
of days needed to provide Tenant with 120 days to complete the Tenant Work.

         5.        Use of the Premises. Tenant shall not use or occupy, or
permit or suffer to be used or occupied, the Premises or any part thereof, other
than for the Permitted Use (set forth in Article 1.8), and except for any retail
uses that may be permitted on the first floor of the Centerpointe I Building
pursuant to Article 14.1.2 below.

         6.        Base Rent.

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                   6.1.1.  Covenant to Pay. Tenant covenants that it shall,
without any demand therefor and without set off or deduction whatsoever (except
as may be expressly permitted pursuant to Article 53.2 below), pay to Landlord
at Landlord's Address (set forth in Article 1.9) or to such other person and at
such other place as Landlord may from time to time designate in writing, in
lawful money of the United States of America, rent at the annual rate of the
Base Rent. Base Rent shall be payable monthly in installments (each a "Monthly
Installment of Base Rent"), in advance on or before the first day of each and
every calendar month during the Term from and after the Rent Commencement Date,
as to the Initial Space, and from and after the applicable Subsequent Rent
Commencement Date, as to each applicable segment of the respective Subsequent
Space.

                   6.1.2.  Advance Deposit of Base Rent. At the time of
execution of this Lease Tenant shall pay to Landlord an amount equal to the
first Monthly Installment of Base Rent for the Initial Space, to be applied by
Landlord on the Rent Commencement Date.

                   6.2.    Partial Month. If the Rent Commencement Date or a
Subsequent Rent Commencement Date is other than the first day of a month, Rent
(defined in Article 50.12), including, without limitation, Base Rent, due from
such date until the first day of the following month shall be prorated and shall
be payable on the Rent Commencement Date or the Subsequent Rent Commencement
Date, as applicable.

                   6.3.    Escalation of Base Rent. Commencing on May 1, 1994
("Escalation Date"), and on the first day of each May during the Term thereafter
(each a "Subsequent Escalation Date") (each such period from and after the
Escalation Date to the date which is one day prior to the next Subsequent
Escalation Date being herein defined as an "Escalation Period"), Base Rent per
rentable square foot shall be increased for each Escalation Period by an amount
equal to Two and Twenty-Five One Hundredths percent (2.25%) multiplied by the
difference between (i) Base Rent per rentable square foot, at the rate effective
on the day before the applicable Subsequent Escalation Date and (ii) the sum of
the Base Year Operating Expenses and the Base Year Real Estate Taxes per
rentable square foot. In addition to the foregoing escalation of Base Rent, the
Base Rent then in effect shall be increased by One Dollar ($1.00) per rentable
square foot at the beginning of the sixth (6th) Lease Year and by Two Dollars
($2.00) per rentable square foot at the beginning of the eleventh (11th) Lease
Year. By way of illustration of the foregoing formula, if the sum of Base Year
Operating Expenses and Base Year Real Estate Taxes per rentable square foot is
Five Dollars ($5.00), then on the Escalation Date Base Rent per rentable square
foot will increase to $13.90 per rentable square foot from and after the
Escalation Date until the next Subsequent Escalation Date.

                   6.4.    Independent Covenant; Survival. Tenant's covenant to
pay the Base Rent is independent of any other covenant, agreement, term or
condition of this Lease (subject to Article 53.2 below). Without limitation on
other obligations of Tenant which shall survive the expiration of the Term, the
obligation of Tenant to pay Base Rent shall survive the expiration of the Term.

         7.        Additional Rent.

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                   7.1.    Covenant to Pay. In addition to paying Base Rent,
Tenant covenants that it shall without (except as may be otherwise expressly
provided herein) any demand therefor and without set-off or deduction whatsoever
(subject to Article 53.2 below), pay to Landlord at Landlord's Address or to
such other person and at such other place as Landlord may from time to time
designate in writing, in lawful money of the United States of America, within
thirty (30) days of a statement of the amount due therefor (except as provided
in Article 7.5 with respect to estimated payments of Additional Rent and except
that if a different period for payment is specifically set forth, said different
period shall control) the following in this Article 7 (collectively, "Additional
Rent"):

                   7.1.1.  Real Estate Taxes. "Net Real Estate Taxes", as
defined below.

                           (a)       Tenant's Centerpointe I Proportionate Share
(as defined in Article 50.16 below) of Real Estate Taxes (as defined in Article
50.11) for the Centerpointe I Building in excess of Tenant's Centerpointe I
Proportionate Share of Base Year Real Estate Taxes for the Centerpointe I
Building ("Centerpointe I Net Real Estate Taxes").

                           (b)       Tenant's Centerpointe II Proportionate
Share (as defined in Article 50.16) of Real Estate Taxes for the Centerpointe II
Building in excess of Tenant's Centerpointe II Proportionate Share of Base Year
Real Estate Taxes for the Centerpointe II Building ("Centerpointe II Net Real
Estate Taxes").

                           (c)       Tenant's Centerpointe I Net Real Estate
Taxes and Tenant's Centerpointe II Net Real Estate Taxes are herein defined as
"Net Real Estate Taxes".

                           (d)       Upon the written request of Tenant, during
any year of the Term of this Lease, Landlord shall deliver a copy of the real
property tax assessment for the Buildings for that year and shall inform Tenant
whether or not Landlord intends to institute an appeal ("Tax Appeal") of the
real property tax assessment for either or ' both of the Buildings. If,
notwithstanding Landlord's intention not to appeal the real property tax
assessment in a particular year, Tenant in its reasonable judgment determines
that a Tax Appeal should be filed, then Tenant shall deliver written notice of
such determination to Landlord no later than the earlier of (i) thirty (30) days
following Landlord's delivery of Landlord's notice of its decision not to file a
Tax Appeal, or (ii) thirty (30) days prior to the deadline for filing the Tax
Appeal. In such event, Landlord, with counsel designated by Landlord, shall file
and prosecute a Tax Appeal with the same diligence as if Landlord had itself
made the determination to undertake such Tax Appeal, and Tenant may participate
and consult with Landlord in such proceedings. The cost and expense of any Tax
Appeal shall be an Annual Operating Cost, as defined in Article 7.4.1 below. In
the event Landlord receives a rebate or refund of any Real Estate Taxes with
respect to which Tenant has contributed its Proportionate Share hereunder,
Landlord shall deliver to Tenant its Proportionate Share of the rebate or
refund, up to an amount which is equal to the sum of the Net Real Estate Taxes
which may have been paid by Tenant in that year, within thirty (30) days after
the receipt thereof by Landlord.

                           (e)       For the Lease Year commencing January 1,
1996 the parties shall adjust Base Year Real Estate Taxes if the average of the
assessments for the Buildings (as opposed

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to changes in the tax rate or the percentage of the assessment upon which the
rate is based) for calendar years 1993, 1994 and 1995 ("Three Year Average
Assessment") deviates from the 1993 Base Year assessment ("Base Year
Assessment") by more than 5%. If the Three Year Average Assessment is not 5%
higher or 5% lower than the Base Year Assessment, Base Year Real Estate Taxes
shall continue to be 1993 calendar year Real Estate Taxes by the tax rate
effective in calendar year 1993. There shall be no readjustment of Tenant's
Proportionate Share of Real Estate Taxes for Lease Years 1993, 1994 or 1995. If
Base Year Real Estate Taxes are adjusted pursuant to this Article 7.1.1(e), the
escalations to Base Rent made pursuant to Article 6.3 shall be recalculated on
the basis of the adjusted Base Year Real Estate Taxes, and any underpayment or
overpayment of the Base Rent made prior to the adjustment of Base Year Real
Estate Taxes on the basis of the 1993 Base Year Real Estate Taxes during any
Escalation Period shall be paid by Tenant to Landlord, or by Landlord to Tenant,
within thirty (30) days of such recalculation.

                   7.1.2.  Lease Taxes. All Lease Taxes (defined in Article
50.7), unless Tenant shall be prohibited by law from paying the same, in which
event Landlord shall be entitled, at its election, to terminate this Lease by
written notice to Tenant, and Landlord and Tenant shall enter into a new lease
which will provide Landlord with economic benefits of an economic value as
closely as is equitably possible to the economic benefits that Landlord would
have enjoyed had Tenant been lawfully permitted to pay such Lease Taxes.

                   7.1.3.  Tenant Electricity. From and after the date on which
Tenant commences the conduct of its business therein for the Permitted Use, as
to the Initial Space, and as to any Subsequent Space, Tenant shall pay to
Landlord as Additional Rent, within thirty (30) days after receipt from Landlord
of each statement of the amount due, Landlord's actual cost in each period
chosen by Landlord, of supplying such quantity of electricity ("Tenant
Electricity") as is consumed by Tenant in the Premises ("Tenant Electricity
Costs"). Tenant Electricity shall include the electricity supplied to the common
areas of the interior portion (excluding the garage) of the Centerpointe I
Building (including, without limitation, the cost for taxes, fuel adjustment
charges, transfer charges and other like charges regularly passed on to the
consumer by the public utility furnishing electricity to the Buildings). Tenant
Electricity Costs shall be determined by Landlord (i) on the basis of a submeter
installed by Landlord, at Landlord's expense on the first floor of the
Centerpointe I Building and (ii) on the basis of a separate submeter for the
third, fourth and, if and when leased by Tenant pursuant to the first offer
rights described in Article 61 and the expansion rights described in Article 62,
on any other full floors of the Centerpointe II Building, all such meters to be
installed by Landlord at Landlord's expense. For any floor less than a full
floor in the Centerpointe II Building, Tenant Electricity Costs applicable to
such floor shall be determined by deeming Tenant's obligation to be equal to
that fractional share of Tenant Electricity Costs, the numerator of which is the
Rentable Area of the Premises on that floor and the denominator of which is the
Rentable Area of all leased premises on such floor of the Centerpointe II
Building which share a common electrical submeter and which were occupied during
the period in question, with equitable adjustments being made for occupancy
during only portions of such period. The calculation of the billing in said
statement shall be determined by Landlord in good faith, using reasonable
accounting principles, it being understood that Landlord shall not derive any
profit from the supplying of electricity. Landlord shall pass on to Tenant the
benefit of any bulk or

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discount rates for electricity that Landlord is able to obtain for the Buildings
and Landlord agrees to use its best efforts to obtain such reduced rates.

                   7.1.4.  Other Sums.  All other sums payable under this Lease
for any purpose, whether or not they are expressly designated as "Additional
Rent" or rent or would otherwise be considered rent, are herein payable as
"Additional Rent".

                   7.2.    Independent Covenant: Survival.  Tenant's covenant to
pay the Additional Rent is independent of any other covenant, agreement, term or
condition of this Lease (subject to Article 53.2 below). Without limitation on
other obligations of Tenant which shall survive the expiration of the Term, the
obligation of Tenant to pay Additional Rent shall survive the expiration of the
Term.

                   7.3.    Partial Year.  If the Rent Commencement Date is not
the first day of a calendar year or if the expiration date of the Term is not
the last day of a calendar year, the amount computed as Additional Rent with
respect to such partial calendar year under this Article 7 shall be prorated in
proportion to the portion of such calendar year falling within the Term.

                   7.4.    Operating Costs.  Tenant shall also pay as
"Additional Rent", "Net Annual Operating Costs", as defined below.

                           (a)       Tenant's Centerpointe I Proportionate Share
of Annual Operating Costs for the Centerpointe I Building in excess of Tenant's
Centerpointe I Proportionate Share of Base Year Operating Costs for the
Centerpointe I Building ("Centerpointe I Net Annual Operating Costs");

                           (b)       Tenant's Centerpointe II Proportionate
Share of Annual Operating Costs for the Centerpointe II Building in excess of
Tenant's Centerpointe II Proportionate Share of Base Year Operating Costs for
the Centerpointe II Building ("Centerpointe II Net Annual Operating Costs");

                           (c)       Tenant's Centerpointe I Net Annual
operating Costs and Tenant's Centerpointe II Net Annual Operating Costs are
together defined as "Net Annual Operating Costs".

         7.4.1.    The term "Annual Operating Costs" shall mean the direct
actual costs to Landlord, determined consistently on a cash, accrual or modified
accrual basis, at Landlord's option, of operating and maintaining the Property
during each calendar year of the Term. Consistent with the operation of a first
class office building in the Northern Virginia area, Landlord agrees to use its
reasonable efforts to minimize Annual Operating Costs to the same extent as if
the entire burden thereof were an unreimbursable obligation of Landlord. Such
'costs shall include, by way of example rather than of limitation, (A) charges
for, and taxes on, the furnishing to the Property of water and sewer service,
electric energy to common areas (other than interior common areas of the
Centerpointe I Building, the payment of which is governed by Article 7.1.3
above) and, if the building systems should be converted to receive the same,
steam or fuel and other utility services; (B) costs of elevator service,
maintenance of the Property, janitorial service and trash removal; (C)

                                       10
<PAGE>

charges for governmental permits; (D) wages, salaries and benefits of employees
of Landlord, or of any management company, who are directly involved in
management of the Property (which costs shall be equitably allocated among the
buildings serviced by such employee), and management fees, overhead and
expenses; (E) premiums for hazard, rent, liability, worker's compensation and
other insurance; (F) costs arising under service contracts; (G) legal, auditing
and other professional and consulting fees; (H) repairs, replacements and
improvements which are in Landlord's reasonable judgment necessary to cause the
Buildings to comply with changes in existing law arising from and after the date
hereof or those which reduce or are expected or intended to result in a net
reduction (taking into account the cost of such improvement) in Annual Operating
Costs, in which case the cost thereof shall be included in Annual Operating
Costs as set forth in Article 7.4.3 below; (I) taxes, including the Fairfax
County BPOL gross receipts and gross expenditures taxes (other than Real Estate
Taxes and state and federal income taxes and any other income, profit,
franchise, capital stock, excise, estate, gift, succession, transfer or
recordation tax or levy); (J) charges, if any, for the Buildings' share of the
costs of (i) any common means of vehicular access and loading facilities and
(ii) common facilities which the Buildings may share with others, (K) the cost
of all other items which under standard accounting practices constitute
operating or maintenance costs which are reasonably allocable to the Property or
any portion thereof.

                                       11
<PAGE>

                   7.4.2.  The term "Annual Operating Costs" shall not include:
(A) depreciation; (B) principal and interest on encumbrances; (C) ground rents;
(D) costs actually reimbursed through insurance proceeds to repair or replace
damage by fire or insured other casualty; (E) compensation and benefits of
executive officers of Landlord (or its managing agent above the level of
building manager; (F) Electricity Costs)(defined in 1,101--Article 7.1.4); (G)
commissions payable to leasing brokers and advertising costs and other
marketing expenses associated with procuring new tenants; (H) expenditures for
capital improvements except those referred to in Section 7.4.1(H); (I) costs
actually reimbursed by condemnation awards or under contractor warranties; (J)
costs of preparing tenant space for other tenants; (K) legal fees relating to
preparation of tenant leases, financing of the Buildings and violations by the
Landlord or any tenant under tenant leases; (L) fees or charges paid to any
Affiliate of Landlord to the extent such fees or charges exceed the fees or
charges that would have been incurred to an independent entity in an arm's
length transaction; (M) cost of utilities and services furnished to retail
tenants who pay directly for such utilities and services under their leases;
(N) costs of original artwork; (0) costs of furnishing any additional or
special service to any tenant, if such service is not also available to Tenant
at no charge; (P) costs of upgrading the common areas of the Buildings beyond
the level of maintenance, repair, modification and replacement necessary to
preserve the first class standard of quality prevailing in such areas on the
date of this Lease; (Q) the cost of any fine for Landlord's failure to comply
with any laws for which this Lease imposes the obligation on Landlord to
comply, (R) the wages and benefits of any personnel employed to manage the
garage; (S) the cost of any personnel, materials or services shared by the
Buildings and any other buildings owned or operated by Landlord, to the extent
reasonably allocable to such other buildings; (T) annual increases in rent for
the space occupied by the management office in a Building in excess of annual
increases in the Consumer Price Index (CPI-W), DC-MD-VA; and (U) phase outs of
chlorofluorocarbon refrigerants which do, not result in a net decrease in
Annual Operating-Costs.

                   7.4.3.  If there shall be purchased any item of capital
equipment or made any capital expenditure required by changes in existing law or
designed to result in net savings or reductions in Annual Operating Costs
(including any phase outs of chlorofluorocarbon refrigerants which result in a
net decrease in Annual Operating Costs) incurred or expected to be incurred or
in Electricity Costs applicable to the Buildings generally, then the costs for
same shall be included in Annual Operating Costs for the calendar year in which
the costs are incurred and subsequent calendar years, on a straight line basis,
to the extent that such items are amortized over their useful life, as
determined pursuant to Generally Accepted Accounting Principles, with an
interest factor equal to the Landlord's actual cost of funds. If there shall be
leased any capital equipment to meet requirements of the law or designed to
result in savings or reductions in Annual Operating Costs, or in Electricity
Costs applicable to the Buildings generally, then the rental and other costs
paid for such leasing shall be included in Annual Operating Costs for the
calendar years in which they were incurred, but only to the extent that the
amortized cost of such items could have been included hereunder had they been
purchased.

                   7.4.4.  In determining Annual Operating Costs for any year,
including Base Year Operating Expenses, if for thirty (30) or more consecutive
days less than 100% of the Rentable Area of the Centerpointe I Building or the
Centerpointe II Building shall have been occupied by tenants, or if any tenant
is separately obtaining janitorial services or any other services being

                                       12
<PAGE>

furnished by Landlord hereunder, then Annual Operating Costs shall be deemed for
such year to be an amount equal to the like expenses that would normally be
expected to be incurred had such occupancy of the Centerpointe I Building and
the Centerpointe II Building been at least 100% throughout such year, and had
Landlord been furnishing all customary services to tenants, as reasonably
determined by Landlord. In making the adjustment called for under this Article
7.4.4, Landlord shall not adjust any element of Annual Operating Costs which
would not vary with the occupancy rate of the Buildings. This Article 7.4.4
shall not be applied in a manner which would enable Landlord to recover from the
tenants in either Building any amount in excess of the costs actually incurred
by Landlord that are attributable to the occupied premises in such Building.

                   7.4.5.  If, at any time during the Term of this Lease Tenant
shall vacate all or any portion of the Premises (and such portion of the
Premises shall not be occupied by any assignees or sublessees of Tenant), then,
to the extent that Landlord is able to suspend janitorial services for such
portion of the Premises vacated by Tenant and receive a reduction of the amounts
owing under Landlord's janitorial contract, Landlord shall credit against
Tenant's Base Rent obligation under this Lease the amount by which Landlord is
able to reduce its janitorial costs with respect to the vacant space (but not by
more than the janitorial costs incurred with respect to such space in the Base
Year).

                   7.5.    Payment of Estimated Additional Rent.  Anything
contained in this Lease to the contrary notwithstanding, Landlord shall be
entitled, at its discretion, to make reasonable estimates, prior to April 30 of
each calendar year, of the amounts of Additional Rent to become due for Net
Annual operating Costs and Net Real Estate Taxes for any full or partial
calendar year under this Article, and to require Tenant to pay, (i) in the case
of Net Annual Operating Costs, such estimated amounts in equal monthly
installments on the first day of each month during each calendar year, and (ii)
in the case of Net Real Estate Taxes, such estimated amounts in equal monthly
installments on the first day of each month during a 12-month period ending not
more than 60 days before the last day in each calendar year when any annual Real
Estate Tax may be paid without interest or penalty; provided, however, that
whenever an estimate of Additional Rent shall be revised as aforesaid, Landlord
shall have the right to increase the monthly installments to be paid thereafter
for that category so that such installments, when added to the installments
which Tenant was theretofore required to pay for the same category, shall equal
the increased estimate. Landlord's estimate of Annual Operating Costs for the
upcoming calendar year shall not exceed the Annual Operating Costs incurred
during the preceding calendar year by more than ten percent (10%). After the end
of each calendar year (for Net Annual Operating Costs) or the end of the
applicable 12-month period (for Net Real Estate Taxes), Landlord shall cause the
actual amount of such Additional Rent to be computed and statements thereof to
be sent to Tenant; and Tenant shall, within 30 days after any statement is sent
to Tenant, pay to Landlord the amount of any deficiency shown therein. If such
statement shall show that Tenant has made an overpayment, Tenant shall receive a
credit to the extent of such overpayment, which credit shall be made against the
installment of Base Rent next falling due hereunder, or refunded to Tenant if
occurring at the end of the Term, and Landlord's obligation to fund such a
refund shall survive the expiration of the Term of this Lease.

                                       13
<PAGE>

                   7.6.    Disputes.  Unless Tenant, within 180 days after
Landlord shall deliver to Tenant Landlord's computation of Base Year Operating
Expenses and Base Year Real Estate Taxes, or any other statement of Additional
Rent, shall give notice to Landlord that Tenant disputes said statement,
specifying in detail the basis for such dispute, each statement furnished to
Tenant by Landlord under any provision of this Article shall be conclusively
binding upon Landlord and Tenant as to the particular Additional Rent due from
Tenant for the period represented thereby. Pending resolution of any dispute,
Tenant shall pay the Additional Rent in accordance with the statements furnished
by Landlord. Notwithstanding the foregoing, if Tenant in any year shall timely
elect to cause an audit to be performed of Landlord's statement, and the audit
reveals, in Tenant's reasonable judgment, that a component of the Annual
Operating Costs may have been incorrectly charged in the past, Tenant shall have
the right to review Landlord's books as to that item only, for the three
calendar years prior to the year in which the audit is performed and any
discrepancies shall be adjusted, and any reimbursement of the cost of the audit,
shall occur as provided below (except that the standard of a 5% discrepancy
giving rise to an obligation on the part of Landlord to reimburse Tenant's audit
costs shall relate to the components of Operating Costs that Tenant was entitled
to audit for such prior years, rather than to Operating Costs in the aggregate).
Landlord agrees, upon prior written request, to make Landlord's books and
records which are relevant to any operating statement available at Landlord's or
its agent's offices during normal business hours for inspection by Tenant and by
a "Big Six" accounting firm (or other national or regional accounting firm to be
approved by Landlord, which approval shall not be unreasonably withheld or
delayed) representing Tenant at Tenant's sole expense (unless Tenant's
inspection or audit discloses a discrepancy of more than five percent (5%) in
the Annual Operating Costs, 'in which event the audit or inspection shall be at
Landlord's expense), provided that any disputed amounts shall have been paid by
Tenant to Landlord. Any discrepancy disclosed by the inspection or audit by
Tenant's "Big Six" accounting firm (or other national or regional accounting
firm approved by Landlord as aforesaid) shall be corrected by payment of any
shortfall to Landlord by Tenant within thirty (30) days after the discrepancy is
revealed, or by a credit against the next payment(s) of Base Rent or Additional
Rent hereunder.

         8.        Late Charge; Interest. If any payment or any part thereof to
be made by Tenant to Landlord pursuant to the terms of this Lease shall become
overdue for a period in excess of five (5) calendar days, a "Late Charge" of
$.03 for each dollar so overdue shall be paid by Tenant for the purpose of
defraying the expense incident to handling such delinquent payment, together
with interest from the date when such payment or such part thereof was due, at
the Lease Interest Rate (defined in Article 50.6). The foregoing "Late Charge"
(but not interest at the Lease Interest Rate) shall not be payable, however, for
the first two (2) infractions during any twelve (12) month period. Nothing
herein shall be construed as waiving any rights of Landlord arising out of any
default of Tenant, by reason of Landlord's imposing or accepting any such Late
Charge or interest; the right to collect the Late Charge and interest is
separate and apart from any rights relating to remedies of Landlord after
default by Tenant including, without limitation, the rights of Landlord pursuant
to Article 31 of this Lease.

         9.        Services.

                                       14
<PAGE>

                   9.1.    Landlord agrees that when Tenant occupies the Initial
Space and the Subsequent Space for the Permitted Use, it shall provide or cause
to be provided the following:

                   9.1.1.  HVAC.  In accordance with standards appropriate for a
first-class office building attached hereto as Exhibit "G", furnish heat,
ventilation and air-conditioning to the Premises during ordinary Business Hours
(defined in Article 50.8) by a "Variable Air Volume System", subject to the
following: (A) Heating and/or air-conditioning supplied to Tenant during times
other than Ordinary Business Hours ("HVAC Off-Hours") required by Tenant shall
be supplied on a floor-by-floor basis upon reasonable prior notice, and shall be
paid for by Tenant as Additional Rent within 30 days after Tenant's receipt of
each bill therefor, at the "HVAC Off-Hours Rate" (defined in Article 50.4); (B)
Landlord shall not be responsible for the failure of the heating or
air-conditioning system to meet the aforesaid standards if such failure results
from occupancy of the Premises by more than an average of one person for each
100 square feet of usable space or if Tenant uses equipment and the combined
electrical load of Tenant's equipment exceeds 4.0 watts, 120 volts per square
foot of floor area in any one room or area; (C) In addition, if the Premises are
used in a manner exceeding the aforementioned occupancy or electric load
criteria, Tenant shall pay to Landlord as Additional Rent, within 30 days after
Tenant's receipt of each bill therefor, Landlord's costs of supplying heating or
air conditioning resulting from such excess, at such rates as Landlord shall
establish therefor; (D) If, due to the use of the Premises in a manner exceeding
the aforementioned occupancy or electrical load criteria or if Tenant has
requested and installed a supplemental HVAC system, or due to the arrangement of
partitioning or the distribution system within the Premises, impairment of
normal operation of the heating or air-conditioning in the Premises results,
necessitating changes in the heating or air-conditioning distribution system
within the Premises, such changes may be made by Landlord upon request by
Tenant, subject to the provisions of Article 9.2 of this Article 9; Tenant shall
pay to Landlord as Additional Rent the cost of any such change within 30 days
after Tenant's receipt of a bill therefor; (E) Tenant agrees at all times to
cooperate fully with Landlord and to abide by all necessary regulations and
requirements which Landlord may prescribe for the proper functioning and
protection of the heating and/or air-conditioning system; (F) The foregoing
heating and air-conditioning services shall be subject to any statute,
ordinance, rule, regulation or resolution for energy conservation which may be
promulgated by any governmental agency or organization and which Landlord shall,
in Landlord's reasonable opinion, be by law required to abide by.

                   9.1.2.  Elevators.  Provide passenger elevator service to the
Premises during ordinary Business Hours, with two elevators in each Building
subject to call at all other times. Provide freight elevator service to the
Premises subject to reasonable scheduling by Landlord.

                   9.1.3.  Access.  Furnish to Tenant's employees and agents
access to the Premises (including the fire stairs for transportation between
floors of the Premises, subject to any code requirements) and garage at all
times, subject to compliance with such reasonable security measures as shall be
from time to time in effect for the Buildings. In addition, Tenant shall have
such access to the roof of the Buildings as will be necessary for Tenant to
construct and maintain the alterations as described in Article 15.2 below.
Tenant may use (i) the kitchen exhaust shaft in the Centerpointe I Building for
data and telecommunications wiring, unless Landlord elects to

                                       15
<PAGE>

terminate such right in order to increase the fresh air capacity in the
Centerpointe I Building, and (ii) the existing auxiliary cooling towers on the
roof of the Centerpointe I Building.

                   9.1.4.  Janitorial.  Provide to the Premises janitorial
service in accordance with the schedule annexed hereto as Exhibit "E". Any and
all additional or specialized janitorial service desired by Tenant shall be
contracted for by Tenant directly and the cost and payment thereof shall be the
sole responsibility of Tenant.

                   9.1.5.  Water.  Provide hot and cold water, and lavatory and
toilet fixtures at the Buildings' core, and water fountains, on each floor.

                   9.1.6.  Public Areas.  Keep and maintain the public areas of
the Buildings clean and in good working order, and the sidewalks adjoining the
Buildings clean and in good repair and substantially free from accumulations of
snow and ice.

                   9.1.7.  Repairs.  Make all structural repairs to the
Buildings, all repairs which may be needed to the mechanical, HVAC, electrical
and plumbing systems in and servicing the Premises, and all repairs to exterior
or atrium windows and glass (including caulking and weather-stripping) and all
repairs to the common and public areas and facilities of the Buildings and the
Property (including those portions of the Centerpointe I Building that would be
common or public areas if such Building was a multi-tenant Building).

                   9.1.8.  Electricity.  Furnish electric energy as required by
Tenant for general light and power use in the Premises, in addition to the
electric energy required by Tenant for distribution of the Buildings' heating,
ventilation and air-conditioning systems to the Premises, all subject to the
following:

                           (a)       With respect to light fixtures standard in
the Buildings, Landlord shall furnish and install all replacement fluorescent
tubes, starters, lamps and ballasts required in the Premises, with the expense
thereof to be included in Annual Operating Costs.

                           (b)       Tenant's use of electric energy in the
Premises shall not at any time exceed the capacity of any of the electrical
conductors and equipment in or serving the Premises. In the event that Tenant
shall require electric energy for use in the Premises (exclusive of such
electric energy as is required for distribution of the heating, ventilating and
air-conditioning systems to the Premises) in excess of 4.0 watts per square foot
as hereinabove provided, and if, in Landlord's reasonable judgment, Landlord's
facilities are inadequate for such additional requirements and if electric
energy for such additional requirements is available to Landlord, Landlord, upon
written request and at the cost and expense of Tenant, will furnish and install
such additional wires, risers, conduits, feeders, switchboards and circuit
panels as reasonably may be required to supply such additional requirements of
Tenant, provided (x) that the same shall be permitted by applicable laws and
insurance regulations, (y) that, in Landlord's reasonable judgment, the same are
necessary and will not cause damage or injury to the Buildings or the Premises
or cause or create a dangerous or hazardous condition or entail excessive or
unreasonable alterations or repairs or interfere with or disturb other tenants
or occupants and (z) that Tenant, at Tenant's expense, shall, concurrently with
the making of such written request, execute and deliver

                                       16
<PAGE>

to Landlord Tenant's written undertaking, in form and substance reasonably
satisfactory to Landlord, obligating Tenant to fully and promptly pay the entire
cost and expense of so furnishing and installing any such additional wires,
risers, conduits, feeders, switchboards, and/or circuit panels, subject to
Article 9.2 of this Article 9.

                   9.2.    Tenant shall not install any equipment of any kind
whatsoever which might necessitate any changes, replacements or additions to any
of the heating, ventilating, air-conditioning, electric, sanitary, elevator or
other systems serving the Premises or any other portion of the Buildings, or to
any of the services required of Landlord under this Lease, without the prior
written consent of Landlord, which shall not be unreasonably withheld so long as
there is no adverse impact on any other tenant of a Building and there is no
other adverse impact on the structural integrity of the Buildings, and in the
event such consent is granted, such replacements, changes or additions shall be
paid for by Tenant at Tenant's sole and exclusive expense. At the expiration or
earlier termination of the Term, Tenant shall pay Landlord's cost of restoring
such systems to their condition prior to such replacements, changes or additions
if at the time that Landlord granted its consent to the replacements, changes or
additions, Landlord conditioned its consent to their removal at the end of the
Term or earlier termination of this Lease. Landlord agrees not to unreasonably
require the removal of systems that are customarily installed in office
buildings.

                   9.3.    In case of accident, strikes, inability to obtain
supplies, breakdowns, repairs, renewals or improvements to the Buildings or
replacement of machinery therein, or for other cause deemed sufficient by
Landlord in its good faith judgment, the operation of the elevators or other
machinery or apparatus may be changed or suspended. As to heat, ventilation,
air-conditioning, cleaning, electricity, elevator, access, janitorial, water,
repairs and any other services provided to the Premises or Buildings, Landlord
shall not be responsible or liable in any way for any failure, defect in supply
or character of, interruption or inadequacy in the quantity or quality of the
same where caused by war, civil commotion, governmental restrictions or
regulations, strikes, labor disturbances, inability to obtain adequate supplies
or materials, casualties, repairs, replacements, or act or omission or
requirement of the public utility serving the Buildings, or any other cause
beyond Landlord's reasonable control whether similar or dissimilar to the
foregoing. Notwithstanding the foregoing, if any interruption of utilities or
services shall continue for more than five (5) consecutive business days and
shall render any portion of the Premises unusable for the normal conduct of
Tenant's business, and if Tenant in fact ceases to use and occupy such portion
of the Premises for the normal conduct of its business because of its inability
due to the interruption (other than, e.g., entry to retrieve files and other
materials), then all Rent payable hereunder with respect to such portion of the
Premises shall be abated retroactively to the first (1st) day of such
interruption and continuing until full use of such portion of the Premises is
restored to Tenant.

                   9.4.    Any service which Landlord is required to furnish
hereunder may, at Landlord's option, be furnished from time to time in whole or
in part by employees of Landlord, by Landlord's managing agent or by others.

                                       17
<PAGE>

                   9.5.    Tenant understands that persons selected by Landlord
to provide services which Tenant is entitled to (or elects to) receive may be
allowed by Landlord to perform these or other services at the Centerpointe II
Building for other tenants at the direct cost and expense of tenants. Tenant
acknowledges that such persons are independent contractors and not agents or
instrumentalities of Landlord and that such arrangements as Tenant may enter
into with such persons are independent of this Lease. Landlord's engagement of
any such independent contractors shall not diminish or impair Landlord's
obligation to provide the services and the level of services required by this
Lease.

                   9.6.    Landlord and Tenant acknowledge that janitorial
services for the Buildings shall initially be furnished by Red Coat, Inc.
Landlord shall not employ any other cleaning contractor for the Centerpointe I
Building without Tenant's prior written approval, which shall not be
unreasonably withheld, conditioned or delayed. In the event Tenant determines
that the janitorial services being furnished by Landlord pursuant to Article
9.1.4 above are unsatisfactory, in Tenant's reasonable judgment, Tenant shall
deliver written notice to Landlord specifying in detail the manner in which the
services are deemed deficient. If the deficiencies are not, in Tenant's
reasonable judgment, substantially corrected during the next succeeding sixty
(60) days, then Tenant may deliver a further notice to Landlord advising
Landlord of such fact and Landlord shall either terminate the contract for
janitorial services to the Buildings or submit the matter to arbitration in
accordance with Article 65 below. If the arbitrator decides in favor of Tenant,
Landlord shall terminate the contract for janitorial services to the Buildings.
Promptly thereafter, Landlord shall enter into a new contract for janitorial
services to the Buildings with a contractor approved by Tenant, such approval
not to be unreasonably withheld, conditioned or delayed. If the arbitrator
decides in favor of Landlord, Tenant shall be barred from sending the notice
permitted by this Article 9.6 for a one year period following such
determination.

                   9.7.    Landlord and Tenant acknowledge that the Buildings
shall initially be managed by LPC Commercial Services, Inc. Landlord agrees that
the term of any management agreement for the Buildings shall not exceed two (2)
years, shall be terminable with cause upon sixty (60) days' prior written notice
and that the fee payable to any manager under each contract shall be at the
then-prevailing market rate for first class buildings comparable to the
Buildings in the Northern Virginia area. In the event Tenant determines that the
manager of the Buildings is not operating the Buildings in a first class manner,
in Tenant's reasonable judgment, then Tenant may deliver written notice to
Landlord specifying in detail the manner in which the operation of the Buildings
is deemed deficient. If the deficiencies are not, in Tenant's reasonable
judgment, substantially corrected during the next succeeding sixty (60) days,
then Tenant may deliver a further notice to Landlord advising Landlord of such
fact and Landlord shall either terminate the contract for management services to
the Buildings or submit the matter to arbitration in accordance with Article 65
below. If the arbitrator decides in favor of Tenant, Landlord shall terminate
the management contract for the Buildings. Promptly thereafter, Landlord shall
enter into a new contract for management services to the Buildings with a
managing agent approved by Tenant, such approval not to be unreasonably
withheld, conditioned or delayed. If the arbitrator decides in favor of
Landlord, Tenant shall be barred from sending the notice permitted by this
Article 9.7 for a one year period following such determination.

                                       18
<PAGE>

                   9.8.    In the event Tenant at any time after the Base Year
requests with specificity that Landlord adjust (either to increase or to
decrease) the level of services being furnished to the Centerpointe I Building,
Landlord agrees to confer with Tenant about such request and to make any
adjustment requested by Tenant that does not impair Landlord's operation and
maintenance of the Centerpointe I Building or adversely affect Base Year
Operating Expenses. Landlord agrees to consult with Tenant at Tenant's request
from time to time about the services being furnished hereunder to the
Centerpointe I Building, and not to adopt or materially modify an annual
operating budget for the Centerpointe I Building without first reviewing said
budget with Tenant.

         10.       Repairs and Condition of Premises. Tenant covenants that at
the expiration or other termination of this Lease, Tenant shall leave the
Premises, and during the Term will keep the same, in good order and condition,
ordinary wear and tear, damage by fire or other casualty alone excepted; and for
that purpose and except as stated, Tenant will make all necessary repairs and
replacements that are not the responsibility of Landlord under this Lease.
Tenant shall also at all times (subject to Article 9.1.4 hereof) remove all
dirt, rubbish, waste and refuse from the Premises and at the termination of the
Term will also have had removed all of Tenant's property therefrom, to the end
that Landlord may again have and repossess the entire Premises in good order and
condition. In the event that any repair is required by reason of such removal or
any negligence or abuse of Tenant or its agents or employees, Landlord may,
after providing Tenant with notice (except in cases of emergency) of Landlord's
intent to make such repair and Tenant's failure to make such repair within five
(5) days of receipt of such notice, make such repair and Tenant shall, upon
demand pay to Landlord as Additional Rent the cost actually and reasonably
incurred by Landlord thereof, together with interest thereon at the Lease
Interest Rate.

         11.       Compliance with Law. Tenant agrees to comply promptly with
all laws, ordinances, regulations and other requirements whatsoever, including
without limitation environmental laws, of any and all Federal, State, or local
authorities or of the Board of Fire Underwriters or any insurance organizations,
associations or companies, with respect to the Premises and any property owned
or leased by Tenant and located within the Premises, subject, however, to
Landlord's obligations under Article 9 above, this Article 11 and Article 52
below. Landlord and Tenant each agree that neither shall knowingly do or commit,
or suffer to be done or committed anywhere in the Buildings, any act or thing
contrary to any of the laws, ordinances, regulations and requirements
hereinabove referred to in this Article. Tenant shall give Landlord prompt
written notice of any accident in the Premises and of any breakage, defect or
failure in any of the systems or equipment servicing the Premises. Landlord
shall be responsible for any required compliance with legal requirements
relating to the condition of the base Buildings (not relating to tenants'
individual uses of their premises or any tenant work associated with their
premises). If a condition exists such that if Tenant were to complete the Tenant
Work as provided herein Tenant would be unable to obtain the required
certificate of occupancy (or nonresidential use permit, if applicable) so that
Tenant would be unable to lawfully occupy the Premises for the Permitted Use
because of any violation of a legal requirement relating to the condition of the
base Buildings as aforesaid, Tenant shall notify Landlord in writing of such
violation. Landlord shall use its best efforts to cure the defect and shall have
ninety (90) days to satisfy such legal requirement or to obtain the certificate
of occupancy (or non-residential use permit, if applicable) on behalf of Tenant.
There shall be an equitable abatement of Rent for portions of the Premises

                                       19
<PAGE>

which Tenant would not lawfully be able to occupy equal to the length of the
period that Tenant is actually delayed in occupying that space. If Landlord has
not satisfied the legal requirement or otherwise obtained the certificate of
occupancy (or non-residential use permit, if applicable) for Tenant within such
ninety (90) days, Tenant shall have the right to terminate this Lease which
shall be Tenant's sole remedy under this Article 11.

         12.       Estoppel Certificate.

                   12.1.   Tenant shall from time to time, within fifteen (15)
days after Landlord's request or that of any mortgagee of Landlord, execute and
deliver to Landlord a written instrument certifying (i) that this Lease is in
full force and effect and has not been modified, supplemented or amended (or, if
there have been modifications, supplements or amendments, that it is in full
force and effect as modified, supplemented or amended, and stating such
modifications, supplements and amendments); (ii) the dates to which Base Rent
and Additional Rent and any other charges arising hereunder have been paid;
(iii) the amount of any prepaid rents or credits due Tenant, if any; (iv) if
applicable, that Tenant has accepted possession and has entered into occupancy
of the Premises, and certifying the Lease Commencement Date, each Subsequent
Lease Commencement Date, the Expansion Space Lease Commencement Date (as defined
in Article 62 below), the Rent Commencement Date, each Subsequent Rent
Commencement Date, the Expansion Space Rent Commencement Date (as defined in
Article 62 below) and the Termination Date; (v) whether or not, to the best
knowledge of the Tenant, all conditions under the Lease to be performed by
Landlord prior thereto have been satisfied and whether or not Landlord is then
in default in the performance of any covenant, agreement or condition contained
in this Lease and specifying each, if any, unsatisfied condition and each, if
any, default of which the signer may have knowledge; and (vi) any other fact or
condition reasonably requested. Any certification delivered pursuant to the
provisions of this Article shall be intended to be relied upon by Landlord or
any of its partners and any mortgagee or prospective mortgagee or purchaser of
the Property or of any interest therein.

                   12.2.   The failure of Tenant to execute, acknowledge and
deliver to Landlord a written instrument in accordance with the provisions of
this Article 12 within the fifteen (15) day period above provided shall
constitute an acknowledgment by Tenant, which may be relied upon by any
mortgagee or prospective mortgagee or any purchaser of either or both of the
Buildings or of any interest therein, that this Lease has not been modified,
supplemented or amended except as set forth in Landlord's request, and is in
full force and effect (or in full force and effect as so modified, supplemented
or amended), that the Base Rent, Additional Rent and any other charges arising
hereunder have not been paid beyond the respective due dates immediately
preceding the date of such request, that Tenant has no right of set-off or other
defense to this Lease and of the truth of such other facts and conditions as
shall have been requested to be certified, and shall constitute, as to any
person entitled to rely as aforesaid, a waiver of any defaults which may exist
prior to the date of such request. Notwithstanding the foregoing, Tenant's
failure to furnish such written instrument within five (5) days after Landlord's
second written request therefor, shall constitute a default under this Lease.

                                       20
<PAGE>

                   12.3.   Landlord agrees, upon not less than fifteen (15)
days after receipt of Tenant's written request, to execute and deliver a written
instrument to Tenant containing the statements and certifications set forth in
Article 12.1, with appropriate changes reflecting the identity of the parties
with respect to clause (v) of Article 12.1. Such statement of Landlord shall not
be binding on a Senior Holder with respect to those matters set forth in Article
58 below and may be relied upon by Tenant and any assignee or subtenant of
Tenant.

                   12.4.   The failure of Landlord to execute and deliver to
Tenant a written instrument in accordance with the provisions of Article 12.3
within the fifteen (15) day period above provided shall constitute an
acknowledgment by Landlord, which may be relied upon by any prospective assignee
or subtenant of Tenant, that the Lease has not been modified, supplemented or
amended except as set forth in Tenant's request, and is in full force and effect
(or in full force and effect as so modified, supplemented or amended), that the
Base Rent, Additional Rent and any other charges arising hereunder have been
paid through the respective due dates immediately preceding the date of such
request, and of the truth of such other facts and conditions as shall have been
requested and certified, and shall constitute, as to any person entitled to rely
as aforesaid, a waiver of any defaults which may exist prior to the date of such
request. The provisions of this Article 12.4 shall not be binding upon any
Senior Holder with respect to those matters set forth in Article 58 below.

         13.       Rules and Regulations. Tenant agrees to observe the rules and
regulations for the Buildings attached hereto as Exhibit "F" and made a part
hereof and such additional reasonable rules and regulations and any
modifications thereto made from time to time by Landlord, which, in Landlord's
reasonable judgment, may be desirable for the use, entry, operation and
management of the Premises, the Property or the Buildings, each of which rules
and regulations and any additions and modifications thereto shall be deemed a
part of this Lease with the same effect as though written herein. Tenant
covenants that all such rules and regulations shall be faithfully observed and
complied with by Tenant, and to cause Tenant's agents, employees and invitees
and all those visiting the Premises or claiming under Tenant. Landlord agrees
not to apply the rules and regulations in a discriminatory manner as between
tenants of the Buildings.

         14.       Assignment and Subletting.

                   14.1.1. So long as Tenant is not in default under this
Lease, upon ten (10) days prior written notice to Landlord, Tenant shall have
the right at any time without Landlord's consent to sublet or otherwise permit
the occupancy of all or a portion of the Premises, or to assign this Lease to
any company or entity which is an Affiliate of Tenant or to any company or
entity which is wholly-owned by Tenant or to any company or entity which shall
acquire all of the stock or substantially all of the assets of Tenant. Any
sublessee or assignee permitted pursuant to this Article 14.1.1 without
Landlord's prior consent shall be bound by all restrictions on transfer under
this Article 14 generally.

                   14.1.2. Tenant shall not mortgage, pledge or encumber this
Lease, collaterally or otherwise. Except as provided in Section 14.1.1 above,
Tenant shall not assign this Lease, or sublet or underlet the Premises or any
part thereof, or permit any other person or entity to occupy

                                       21
<PAGE>

the Premises or any part thereof, without on each occasion first obtaining the
written consent of Landlord, which consent shall not be unreasonably withheld,
conditioned or delayed by Landlord. Without limiting the foregoing, Tenant
acknowledges that it shall be reasonable for Landlord to withhold its consent if
such subtenant's or assignee's business is not suitable for a first-class office
building or would otherwise inhibit Landlord's marketing efforts or detract from
the value of the Buildings. Further, Landlord shall not unreasonably withhold or
delay its consent to a proposed sublease or subleases of portions of the first
floor of the Centerpointe I Building for retail uses which would constitute an
amenity to Tenant's employees, provided, however, any proposed retail sublease
must not conflict with the terms of any of the then-existing leases for the
Buildings, must be for an amount of space and type of use that complies with all
laws, including but not limited to zoning proffers for the Property, the
proposed use must be suitable for a first-class office building, and must not
otherwise inhibit Landlord's marketing efforts or detract from the value of the
Buildings and must otherwise be in form and substance reasonably satisfactory to
Landlord. In the event that Landlord should withhold its consent to a sublease
or assignment and Tenant should contest the reasonableness of Landlord's action,
the parties shall submit the matter to arbitration pursuant to Article 65 below.

                   14.2.   Except for subleases and assignments permitted
pursuant to Section 14.1.1, at least 20 days prior to any proposed subletting or
assignment, Tenant shall submit to Landlord a statement seeking Landlord's
consent and containing the name and address of the proposed subtenant or
assignee, the terms of the proposed sublease or assignment and such financial
and other information available to Tenant with respect to the proposed subtenant
or assignee as Landlord may reasonably request. Landlord shall indicate its
consent or non-consent within 14 days of its receipt of Tenant's submission. If
Landlord has not responded to Tenant within such 14 day period, Tenant shall
deliver a second notice to Landlord advising Landlord of the proposed assignment
or sublease and Landlord's failure to respond to the second notice within 4 days
of receipt thereof shall be deemed to be consent to the proposed sublease or
assignment. Should Landlord agree to an assignment or sublease, Tenant will pay
to Landlord on demand a sum equal to all of Landlord's reasonable costs,
including reasonable attorneys' fees, incurred in connection with such
assignment or transfer. Landlord shall furnish written reasons for any
non-consent.

                   14.3.   Tenant shall have 120 days from its receipt of
Landlord's consent as described in Article 14.2 of this Article 14 to enter into
the proposed sublease or assignment substantially in accordance with the terms
and with the identified subtenant or assignee described in Tenant's statement to
Landlord, and in accordance with such other terms required by this Lease, and
Tenant shall submit a fully executed sublease or assignment to Landlord.

                   14.4.   A subletting shall not convey to any subtenant the
right to exercise or receive any lease renewal option rights or space option
rights of the Premises, special privileges or extra services granted to Tenant
by this Lease, or addendum or amendment thereto or letter of agreement. Any
sale, assignment, mortgage or transfer of this Lease or sublease of the Premises
which does not comply with the provisions of this Article 14 shall be void.

                   14.5.   Except for subleases or assignments permitted by
Article 14.1.1, in the event that Tenant at any time desires to sublease or
assign all or part of its interest in the Premises

                                       22
<PAGE>

or the Lease or any portion thereof which, when aggregated with all other
portions of the Premises then subject to subleases collectively comprises
greater than thirty-six percent (36%) of the Premises ("Proposed Recapture
Space"), then Tenant shall deliver a notice to Landlord ("Recapture Notice")
advising Landlord of such fact and specifying in good faith the date as of which
Tenant desires the assignment or sublease to take effect (the "Proposed Transfer
Date"). Tenant may deliver the Recapture Notice prior to identifying a
prospective assignee of this Lease or sublessee of the Proposed Recapture Space.
Landlord shall have the right in its absolute discretion to terminate this Lease
as to the Proposed Recapture Space. Landlord may exercise such right to
terminate by giving written notice to Tenant within twenty-one (21) days after
receipt of the Recapture Notice. If the Proposed Recapture Space does not
constitute the entire Premises and Landlord elects to terminate this Lease with
' respect to the Proposed Recapture Space, then (a) Tenant shall tender the
Proposed Recapture Space to Landlord on the Proposed Transfer Date as if such
specified date had been originally set forth in this Lease as the expiration
date of the Term with respect to the Proposed Recapture Space, and (b) as to all
portions of the Premises other than the Proposed Recapture space, this Lease
shall remain in full force and effect except that the Rent shall be reduced pro
rata. Landlord and Tenant shall promptly enter into an amendment to this Lease
setting forth the new Rentable Area of the Premises and the consequent reduction
in Base Rent and Additional Rent. In the event Landlord does not exercise its
right to terminate this Lease with respect thereto, Tenant shall be entitled to
seek an acceptable assignee or subtenant for the Proposed Recapture Space,
subject to Landlord's consent pursuant to Article 14.2 above.

                   14.6.   An assignment within the meaning of this Lease is
intended to comprehend not only the voluntary action of Tenant, but also any
involuntary action to include without limitation any levy or sale on execution
or other legal process against the leasehold, and every assignment of the
leasehold for the benefit of creditors, and the filing or any petition or order
described in Article 31.1.3 below.

                   14.7.   No subletting or assignment with or without
Landlord's consent shall in any way relieve or release Tenant from liability for
the performance of all terms, covenants and conditions of this Lease.
Furthermore, no assignment will be valid unless the assignee shall execute and
deliver to Landlord an assumption of liability agreement in form reasonably
satisfactory to Landlord, including an assumption by the assignee of all of the
obligations of Tenant and the assignee's ratification of and agreement to be
bound by all the provisions of this Lease; and no subletting will be valid
unless the subtenant first enters into a written agreement that subordinates
such sublease to this Lease and confirms that no provision of such sublease is
inconsistent with the terms and conditions of this Lease. Any successors and
assigns of the Tenant named as Tenant on page I of this Lease shall have the
same obligations and liabilities as it would have possessed had it originally
executed this Lease as the Tenant; any rights, privileges or powers under this
Lease shall inure to the benefit of any such successor or assignee of Tenant,
immediate or remote, only if the assignment to such assignee or successor has
been approved in writing by Landlord or, under the terms of this Lease, is an
assignment for which no approval is required, and such successor or assignee
shall have executed and delivered to Landlord the written documents required by
Landlord referred to hereinbefore, and each and every person hereinabove named
as the Tenant shall be bound jointly and severally by the terms, covenants and
agreements contained herein.

                                       23
<PAGE>

                   14.8.   Although the Permitted Use shall in all events be
limited to that set forth in Article 1.8, for the purpose of protecting any
mortgagee or other investor in the Property from having made certain unfavorable
or unlawful investments, it is agreed that Tenant shall not enter into any
assignment, sublease, license, concession or other agreement for use, occupancy
or utilization of the whole or any part of the Premises with or without
Landlord's consent, which provides for rental or other payment for such use,
occupancy or utilization based, in whole or in part, on the net income or net
profits derived by any person or entity from the space leased, used, occupied or
utilized (other than an amount based on a fixed percentage or percentages of
gross receipts or sales), and any such purported assignment, sublease, license,
concession or other agreement shall be absolutely void and ineffective as a
conveyance or creation of any right or interest in the possession, use,
occupancy or utilization of any part of the Premises.

         15.       Alterations.

                   15.1.   Except for Tenant Work which shall be governed by the
Tenant Design and Construction Process set forth on Exhibit "C", Tenant
covenants to make no alteration, addition or improvement to the Premises without
first submitting a detailed description thereof to Landlord and obtaining
Landlord's written approval thereof, which shall not be unreasonably withheld,
conditioned or delayed, except that Landlord's written approval shall not be
required for painting, wall coverings, carpeting or decorations or for minor,
nonstructural improvements, additions or alterations valued at less than $35,000
in each instance at the time thereof and not adversely affecting the structural,
mechanical, electrical or plumbing systems, or any components thereof, of the
Buildings. Landlord agrees that Tenant may, at Tenant's sole expense and subject
to Landlord's prior approval (which approval will not be unreasonably withheld,
conditioned or delayed) as to size, equipment specifications, architectural
screening and engineering requirements, and subject to all local, county and
state rules, codes, ordinances and statutes, install and maintain: (i)
additional cooling towers or electrical generators on the roof of the
Centerpointe I Building, provided that space availability and structural
capacity permit such installation, and (ii) add air-cooled refrigeration
equipment within the garage level of the Centerpointe I Building or in close
proximity to the Centerpointe I Building and (iii) proprietary equipment or
antennae, HVAC units, communications and data transmission networks on the roof
of the Buildings so long as Tenant does not interfere with rights of other
tenants on the roof of the Centerpointe II Building.

                   15.2.   Provided that the proposed alteration, addition or
improvement does not in Landlord's reasonable judgment involve any modification
to the Buildings' exterior or any material modification to mechanical,
electrical or plumbing systems or components, or impairs the integrity of the
Buildings' structures, such approval shall not be unreasonably withheld or
delayed, but may be conditioned upon compliance with reasonable requirements of
Landlord, including, without limitation, the filing of mechanics' lien waivers
by Tenant's contractors or the posting of a bond to protect against mechanics
liens, and the submission of written evidence of adequate insurance coverage
naming Landlord as an additional insured thereunder.

                   15.3.   Landlord may withhold its approval in its absolute
and sole discretion with respect to each such alteration, addition or
improvement which Landlord reasonably determines involves any modification to
the Buildings' exterior or impairs the integrity of the Buildings' structures,
or involves any

                                       24
<PAGE>

material modification to the Buildings' electrical, mechanical or plumbing
systems or any components thereof.

                   15.4.   Tenant shall not permit any financing statement or
statements to be filed with respect to any of the foregoing alterations,
additions or improvements. All alterations, additions or improvements made by
Tenant and all fixtures attached to the Premises (other than Tenant's trade and
business fixtures and equipment) shall remain at the Premises at the expiration
or sooner termination of this Lease and, upon their installation in the Premises
(unless such alterations, additions or improvements are composed of or contain a
Hazardous Substance), shall become the property of Landlord except that any or
all of the foregoing which may be designated by Landlord for removal in a notice
given at the time Landlord approves the original installation thereof in the
Premises shall be removed at the cost of Tenant before such expiration or sooner
termination and in such event, Tenant shall repair all damage to the Premises
caused by the installation or removal thereof, however, Tenant shall in no event
be required to remove customary items of office construction and finishing, such
as partitions, doors, light fixtures, carpeting and the like. Notwithstanding
anything in the foregoing to the contrary, Tenant shall in all events have the
right (but not the obligation) to remove any raised computer flooring or
supplementary HVAC installed in or about the Premises by or on behalf of Tenant
so long as Tenant restores the Premises following such removal.

                   15.5.   All such alterations, additions or improvements shall
be performed at Tenant's cost by one or more contractors approved by Landlord
(in its reasonable discretion), and shall be made in accordance with the
standards, procedures and requirements set forth in Exhibit "C" to the extent
that any such standards, procedures and requirements reasonably applies to the
proposed alterations, additions or improvements.

                   15.6.   Except as otherwise expressly provided herein, Tenant
shall not place, or cause or allow to be placed, any sign, advertising matter,
lettering, stand, booth, showcase or other article or matter outside of the
Premises, without the prior written consent of Landlord which may be withheld in
its sole discretion.

         16.       Mechanics' and Other Liens.

                   16.1.   Tenant covenants that it shall not (and has no
authority to) create or allow any encumbrance against the Premises, the Property
or the Buildings, or any part of any thereof or Landlord's interest therein.

                   16.2.   Tenant covenants that it shall not suffer or permit
to be created, or to remain, any lien or claim thereof (arising out of any work
done or services, material, equipment or supplies furnished for or at the
request of Tenant or by or for any contractor or subcontractor of Tenant) which
is or may become a lien upon the Premises, the Property or the Buildings, or any
part of any thereof or the income therefrom or any fixture, equipment or similar
property therein.

                   16.3.   If any lien or claim shall be filed, Tenant shall
within 15 days after Tenant receives notice of the filing thereof, cause the
same to be discharged of record by payment, deposit, bond or otherwise. If
Tenant shall fail to cause such lien or claim to be discharged and removed from
record (by bonding or otherwise) within that period, then, without obligation to
investigate the validity thereof and in addition to any other right or remedy
Landlord may have, Landlord may, but shall not be obligated to, contest the lien
or claim or discharge it by posting a

                                       25
<PAGE>

bond, if that method is reasonably practicable, or, if posting a bond is not
reasonably practicable, by payment, deposit or otherwise. Any amounts so paid by
Landlord and all reasonable costs and reasonable expenses, including reasonable
attorneys' fees, incurred by Landlord in connection therewith, together with
interest at the Lease Interest Rate from the respective dates of Landlord's
making of the payment or incurring of the cost or expense, shall constitute
Additional Rent payable by Tenant under this Lease and shall be paid by Tenant
to Landlord promptly on demand.

                   16.4.   Notwithstanding anything contained herein to the
contrary, nothing contained in or contemplated by this Lease shall be deemed or
construed in any way to constitute the consent or request on the part of
Landlord for the performance of any work or services or the furnishing of any
materials for which any lien could be filed against the Premises or the
Buildings or the Property or any part of any thereof, nor as giving Tenant any
right, power, or authority (beyond those set forth in this Lease) to contract
for or permit the performance of any work or services or the furnishing of any
materials for which any lien could be filed against the Premises, the Buildings,
or the Property or any part of any thereof.

         17.       Landlord's Right to Enter. Landlord has the right, and Tenant
will permit Landlord, its agents, employees and any other persons authorized by
Landlord in writing, to enter the Premises at any time in case of an emergency;
to enter the Premises at any reasonable time after reasonable prior notice if
Landlord shall so elect for making alterations, improvements or repairs to the
Buildings or for any purpose in connection with the operation or maintenance or
financing of the Buildings and, if Tenant abandons the Premises, then at any
time to re-enter and renovate the Premises; in any event, no such entry or
renovation shall be considered as a deprivation of Tenant's use of the Premises
or shall give rise to any abatement of Rent and Landlord shall use its best
efforts to avoid any material interference with Tenant's use and enjoyment of
the Premises and whenever reasonably possible cause such entry to occur during
hours other than Standard Operating Hours. In addition, to the extent that
Tenant gives Landlord prior written notice thereof, Landlord shall comply with
Tenant's reasonable security requirements and any security restrictions imposed
by Tenant's governmental or private-sector clients that may apply to any
portion(s) of the Premises.

         18.       Certain Rights Reserved by Landlord. Landlord waives no
rights, except those that may be specifically and expressly waived pursuant to
the terms of this Lease, and explicitly retains all other rights, including,
without limitation, the following rights, each of which Landlord may exercise
without liability to Tenant for damage or injury to property, person or business
on account of the exercise thereof, and the exercise of any such rights shall
not be deemed to constitute an eviction or disturbance of Tenant's use or
possession of the Premises (provided that Landlord shall use its best efforts to
avoid any material interference with Tenant's use and enjoyment of the Premises)
and shall not give rise to any claim for set-off or abatement of Rent or any
other claim:

                   18.1.   To install, affix and maintain any and all signs
which comport with the character of a first class building on the exterior and
on the interior of the Centerpointe II Building or on the exterior or interior
of the Centerpointe I Building if Tenant is no longer the largest tenant of the
Centerpointe I Building.

                                       26
<PAGE>

                   18.2.   To decorate or to make repairs, alterations,
additions, or improvements, whether structural or otherwise, in and about the
Buildings, or any part thereof, and for such purposes to enter upon the Premises
(in accordance with the terms of Article 17 above), and during the continuance
of any of such work, to temporarily close doors, entry ways, public space and
corridors in the Buildings and to interrupt or temporarily suspend services or
use of facilities, all without affecting any of Tenant's obligations hereunder,
so long as the Premises are reasonably accessible and usable.

                   18.3.   To furnish door keys for the entry door(s) in the
Premises at the commencement of the Lease and to retain at all times, and to use
in appropriate instances, keys to all doors within and into the Premises (except
as provided below). Tenant agrees to change no locks, and not to affix locks on
doors without the prior written consent of the Landlord, which consent Landlord
will not unreasonably withhold or delay so long as Tenant gives to Landlord
duplicate keys for any changed locks (subject to any security requirements for
Tenant's clients, which may prohibit delivery of duplicate keys for portions of
the Premises). Upon the expiration of the Term or Tenant's right to possession,
Tenant shall return all keys to Landlord and shall disclose to Landlord the
combination of any safes, cabinets or vaults left in the Premises. Tenant shall
have the right to install an access-control system for the Premises (including
interior areas within the Premises), which may be separate from Landlord's
access-control system for the Buildings or may be an extension of Landlord's
system (at Tenant's expense) to cover the Premises so long as such system does
not interfere with the other access control systems for the Buildings and does
not limit Landlord's access to the Premises as permitted under Article 17 above.
If Tenant extends Landlord's access-control system for the Buildings to cover
the Premises, Landlord shall not thereafter replace the Buildings'
access-control system or change it in a way that impairs the functioning of
Tenant's system without Tenant's prior written approval which approval shall not
be unreasonably withheld or delayed.

                   18.4.   To approve all window coverings used in the
Buildings.

                   18.5.   To approve the weight, size and location of safes,
vaults and other heavy equipment and articles in and about the Premises and the
Buildings so as not to exceed the legal load per square foot designated by the
structural engineers for the Buildings, and to require all such items and
furniture and similar items to be moved into or out of the Buildings and
Premises only at such times and in such manner as Landlord shall reasonably
direct in writing. Tenant shall not install or operate machinery or any
mechanical devices of a nature not directly related to Tenant's ordinary use, as
limited by the Permitted Use, of the Premises without the prior written consent
of Landlord. Movements of Tenant's property into or out of the Buildings or
Premises and within the Buildings are entirely at the risk and responsibility of
Tenant.

                   18.6.   To regulate (pursuant to reasonable rules and
regulations) delivery of supplies and the usage of the loading docks, receiving
areas and freight elevators.

                   18.7.   To enter the Premises in accordance with Article 17,
and in the last year of the Term, to show the Premises to prospective tenants at
reasonable times after reasonable prior

                                       27
<PAGE>

notice to Tenant and, if abandoned, to show the Premises at any time and to
prepare the Premises for re-occupancy.

                   18.8.    To erect, use and maintain pipes, ducts, wiring and
conduits, and appurtenances thereto, in and through the Premises at reasonable
locations.

                   18.9.    To enter the Premises in accordance with Article 17
at any reasonable time to inspect the Premises and to make repairs or
alterations as Landlord deems necessary, with due diligence and minimum
disturbance.

                   18.10.   To grant to any person or to reserve unto itself the
right to conduct any business or render any service in the Buildings.

         19.       Landlord's Liability; Rights.

                   19.1.    It is expressly understood and agreed by Tenant that
none of Landlord's covenants, undertakings or agreements are made or intended as
personal covenants, undertakings or agreements by Landlord or its partners,
shareholders or trustees, or any of their respective partners, shareholders or
trustees, and any liability for damage or breach or nonperformance by Landlord
(that is not covered by Landlord's liability insurance, which shall not in any
way abrogate the waivers set forth in Article 21.4) shall be collectible only
out of Landlord's interest in the Buildings and the rents, the net proceeds of
sale arising therefrom, and insurance and condemnation proceeds actually
collected by Landlord, and no personal liability is assumed by, nor at any time
may be asserted against, Landlord or its partners, shareholders or trustees or
any of its or their partners, shareholders, trustees, officers, agents,
employees, legal representatives, successors or assigns, if any, all such
liability, if any, being expressly waived and released by Tenant.

                   19.2.    The Landlord named on page 1 of this Lease and any
subsequent owners of such Landlord's interest in the Buildings, as well as their
respective heirs, personal representatives, successors and assigns shall each
have the same rights, remedies, powers, authorities and privileges, and
obligations and liabilities, as it would have had had it originally signed this
Lease as Landlord, but any such person, whether or not named herein, shall have
no liability hereunder for acts occurring after it ceases to hold such interest,
provided all such liability arising from and after such date is assumed in a
written agreement between Landlord and such successor owner.

         20.       Unilateral Amendment. Landlord shall have the right at any
time, and from time to time, during the Term of this Lease, to unilaterally
amend the provisions of this Lease if Landlord is advised by its counsel that
all or any portion of the monies paid by Tenant to Landlord hereunder are, or
may be deemed to be, unrelated business income within the meaning of the United
States Internal Revenue Code or regulations issued thereunder, and Tenant agrees
that it will execute all documents or instruments necessary to effect such
amendment or amendments, provided that no such amendment shall result in Tenant
having to pay a larger sum of money on account of its occupancy of the Premises
under the terms of this Lease as so amended, and provided further that no such
amendment or amendments shall result in Tenant receiving under the

                                       28
<PAGE>

provisions of this Lease less services that it is entitled to receive, nor
services of a lesser quality nor otherwise materially and adversely affect the
rights of Tenant under this Lease.

         21.       Insurance.

                   21.1.    Avoidance of Acts Which Increase Insurance Risk.
Landlord and Tenant each covenant that it will not do or commit, or suffer or
permit to be done or committed, any act or thing as a result of which any policy
of insurance of any kind on or in connection with the Buildings or the Property
or any part thereof shall become void or suspended, or the insurance risk on the
Buildings or the Property or any part thereof shall (in the opinion of any
insurer or proposed insurer) be rendered more hazardous. Tenant shall pay as
Additional Rent, within 30 days after being billed therefor, the amount of any
increase of premiums for such insurance resulting from any breach of this
covenant.

                   21.2.    Tenant's Insurance Coverage.  Tenant covenants that
it shall maintain throughout the Term, at Tenant's expense, policies of (i)
commercial general public liability insurance having initial limits of not less
than $5,000,000 per occurrence and annual aggregate combined single limit for
bodily injury and property damage, with a severability of interest endorsement,
and with increases in such limits as may from time to time be commercially
common for tenants of first-class office buildings in the Northern Virginia
area, and (ii) all-risk or fire and extended coverage insurance upon Tenant's
personal property and leasehold improvements in the Premises for the full
replacement value of such personal property and leasehold improvements. Such
policies shall name Landlord (and, if available, Landlord's mortgagees from time
to time) as an additional insured party and shall provide that the policies
shall not be cancelable without at least 30 days' prior written notice to
Landlord and shall be issued by insurers licensed to do business in Virginia and
having a Best's rating of A-XII or higher. Tenant shall furnish Landlord with
certificates of insurance to evidence the existence of such coverage.

                   21.3.    Landlord's Insurance Coverage.  Landlord shall
maintain throughout the Term "all-risk" insurance upon the Buildings. Landlord's
property insurance shall include replacement cost coverage and an agreed amount
endorsement, and shall provide for a commercially reasonable "deductible" for
first class office buildings in the Northern Virginia area. Landlord shall also
carry (or cause to be carried) commercial general liability insurance covering
Landlord and its managing agent having limits of not less than $5,000,000 annual
aggregate combined single limit for bodily injury and property damage and with
increases in such limits equal to any increases from time to time in Tenant's
limits pursuant to Article 21.2 above. Landlord's liability policy shall name
Tenant as an additional insured party. All of Landlord's policies shall be
issued by insurers licensed to do business in Virginia and having a Best's
rating of A-XII or higher. Landlord shall furnish Tenant with certificates of
insurance to evidence the existence of such coverage. The cost of the premiums
for such insurance and of any endorsements thereto shall, for purposes of
Article 7 hereof, be part of the Annual Operating Costs.

                   21.4.    Waiver of Subrogation.  Notwithstanding anything in
this Lease to the contrary, each party hereto hereby releases the other party,
its agents and employees, to the extent

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<PAGE>

the releasing party is, or is required hereunder to be, insured under its
insurance policies, from any and all liability for any loss or damage which may
be inflicted upon the property of such party, notwithstanding that such loss or
damage shall have arisen out of the negligent or other tortious act or omission
of the other party, its agents or employees. Each party hereto shall cause a
clause to be included in each and every policy of property insurance of the
party to the effect that such release shall not affect the right of the insured
to recover thereunder, if such clause is available. If such a waiver of
subrogation cannot be obtained, the party undertaking to carry the insurance
shall notify the other party of such fact, and the other party shall have a
period of 30 days thereafter to place such insurance in companies which are
reasonably satisfactory to the notifying party and will issue such insurance
with waiver of subrogation.

         22.       Fire or Other Casualty.

                   22.1.    Casualty to Centerpointe II Premises.  If the
Centerpointe II Premises (including machinery or equipment used in the operation
of the Centerpointe II Premises) shall be damaged by fire or other casualty
which casualty renders all or a material portion of the Centerpointe II Premises
untenantable, and Landlord elects not to rebuild or restore the Centerpointe II
Premises for any reason, but rather to cease operating the Centerpointe II
Building and to terminate the leases of the tenants therein, the Lease will
terminate as to the Centerpointe II Premises only (with an equitable abatement
of Rent as of the date of the casualty), but Tenant shall have no right to
terminate the Lease for the balance of the Premises in the Centerpointe I
Building provided, however, that (i) American Management Systems, Inc., or (ii)
any assignee of its entire interest in this Lease, or (iii) any sublessee of 90%
or more of the Premises for substantially all of the Term, or (iv) any sublessee
whose sublease term was due to expire less than 36 months following the date of
casualty and there shall be remaining at least 72 months in the Term (any party
in clauses (i) - (iv) above is herein a "Substitute Space Tenant") shall have
the right to lease "Substitute Space" (as hereinafter defined) for the balance
of the Term and Landlord shall have the obligation to pay to such Substitute
Space Tenant the "Substitute Space Differential" (as hereinafter defined) for
the balance of the Term. For purposes of this Article 22.1, the term "Substitute
Space" shall mean office building rental space in the Fair Oaks area of Fairfax
County or otherwise within a one and one-half driving mile radius of the
Centerpointe II Building, or to the South at the intersection of Waples Mill and
Random Hills Road, and of sufficient square footage to accommodate the rentable
square footage occupied by the Substitute Space Tenant in the Centerpointe II
Building in blocks of a full floor or more and otherwise be reasonably
equivalent in quality, features and on-site amenities (except that parking may
be surface lot only) to the Centerpointe II Premises. For purposes of this
Article 22.1, the term "Substitute Space Differential" shall mean the then
present value of the difference between: (i) the ' then base monthly rental and
additional monthly rental payable for the Substitute Space by the Substitute
Space Tenant (plus reasonable moving costs and the cost to build out the
Substitute Space in a manner that is equivalent to the Centerpointe II Premises)
for the remainder of the Term (but not any unexercised renewal terms), and (ii)
the Base Rent and Additional Rent payable under this Lease for the remainder of
the Term (but not any unexercised renewal terms). Any disputes between Landlord
and Tenant regarding the determination of Substitute Space or Substitute Space
Differential shall be determined by arbitration in accordance with Article 65 of
this Lease. If Tenant reasonably determines that no Substitute Space is then
obtainable (the reasonableness of

                                       30
<PAGE>

which determination Landlord may challenge by arbitration pursuant to Article 65
below) then, notwithstanding anything in the foregoing to the contrary, Tenant
shall have the right to terminate this Lease with respect to both the
Centerpointe I Premises and the Centerpointe II Premises.

                   22.2.    Casualty To Centerpointe I Building: Restoration:
Landlord's Right to Terminate

                   22.2.1.  Except as provided in this Article 22.2, if the
Centerpointe I Building (including machinery or equipment used in the operation
of the Centerpointe I Building) shall be damaged by fire or other casualty, then
if permitted by Landlord's mortgagees, and only to the extent that there are
available insurance proceeds, Landlord shall be obligated to repair and restore
the same with reasonable promptness, subject to reasonable delays for insurance
adjustments and to delays caused by matters beyond Landlord's reasonable
control; provided, however, that Landlord shall have no duty to repair or
restore any personal property, or any alterations, additions, improvements or
decorations not originally installed pursuant to the Tenant Work and paid for
with the Concession Fund.

                   22.2.2.  However, if (a) the damage by fire or other casualty
renders all or a substantial part of the Centerpointe I Building untenantable
and occurs at a time such that following the date that the restoration and
repair work is reasonably anticipated to be completed less than 24 months of the
Term will remain; or (b) such fire or other casualty renders fifty percent (50%)
or more of the Rentable Area of the Centerpointe I Building untenantable and
Landlord elects to cease operating the Centerpointe I Building; then in any such
event, Landlord shall have the right to terminate this Lease (with equitable
prorations of Rent being made for Tenant's possession of any tenantable portions
of the Premises subsequent to the date of such damage and prior to the effective
date of such termination) upon giving written notice to Tenant at any time
within 90 days after the date of such damage

                   22.2.3.  If pursuant to Article 22.2.2(a) hereof, Landlord
elects not to repair or restore, Tenant may nullify such election pursuant to
such subsection if Tenant, within 30 days after the date of receipt of
Landlord's notice of election to terminate, exercises any available option to
extend the Term of this Lease for a Renewal Period such that more than 24 months
of the Term will remain after the date the restoration or repair work is
reasonably anticipated to be complete.

                   22.2.4.  Landlord shall have no liability to Tenant for, and
Tenant shall not be entitled to terminate this Lease by virtue of, any delays in
completion of repairs and restoration. Rent, however, shall equitably abate as
to those portions of the Premises as are, from time to time, untenantable as a
result of such damage.

                   22.3     Tenant's Right to Terminate For Centerpointe I
Building Casualty. In the event there shall occur any fire or other casualty
to the Centerpointe I Building after the Lease Commencement Date, Tenant shall
have the right to terminate this Lease in accordance with this Article 22.3. If
the damage by fire or other casualty renders all or a substantial part of the
Centerpointe I Building untenantable and occurs at a time such that following
the date that the restoration and repair work is reasonably anticipated to be
completed, less than 24 months of the Term will remain, Tenant shall have the
right to terminate this Lease. In all other casualty situations, if substantial

                                       31
<PAGE>

completion of the restoration of the Centerpointe I Building does not occur, or
in Landlord's reasonable judgment will not occur, within 365 days after the fire
or other casualty (which 365-day period shall be extended for up to an
additional year to the extent of any delay caused by strikes, lockouts, acts of
god, acts of war or other occurrences beyond Landlord's control), Landlord shall
so notify Tenant in writing, which notice shall include Landlord's reasonable
estimate of the date of substantial completion of the restoration. Tenant, by
giving written notice of termination within 15 business days after its receipt
of Landlord's notice, shall have the right to terminate this Lease effective as
of such date not later than 45 business days after Tenant's receipt of
Landlord's notice, as Tenant may specify in such notice. In the event of such
termination, neither party shall be liable to the other for any liability
relating to the period after termination. If Tenant does not terminate this
Lease as aforesaid, and the substantial completion of the restoration does not
occur by the estimated date of substantial completion contained in the aforesaid
notice, Landlord shall provide within 10 business days after a determination is
made that substantial completion will not occur by the estimated date a second
notice estimating the extended date of substantial completion, and Tenant shall
again have the right, exercisable only by written notice given within 15
business days after the receipt of Landlord's notice, to terminate this Lease
within the 45-day time period set forth above in this Article 22.3. In each
instance in which Tenant elects not to exercise its right to terminate as
provided in this Article 22.3, such right to terminate, following the same
procedure and schedule, shall again arise if substantial completion has not
occurred by the estimated date of substantial completion set forth in the notice
upon which Tenant's previous election not to terminate was based.

         23.       Waiver of Claims; Indemnification.

                   23.1.    Neither Landlord nor any partner, shareholder or
trustee in Landlord shall be held responsible for, and each is hereby expressly
relieved from, any and all liability by reason of any injury, loss, or damage to
any person or property in or about Tenant's Control Area (as defined in Article
52 below) due to any cause whatever, or arising from Tenant's use of the roof,
garage and other facilities in Landlord's Control Area permitted pursuant to
Articles 9.1.3 and 15.1, except for liability arising from the acts within the
Tenant's Control Area of Landlord's cleaning personnel or Landlord's building
engineers, and whether the loss, injury or damage be to the person or property
of Tenant or any other person, unless due to the gross negligence of Landlord,
its servants or employees. Tenant further agrees to indemnify, defend and save
Landlord and each partner, shareholder or trustee in Landlord harmless from and
against all claims by any employee or invitee of Tenant made on account of such
injury, loss or damage (unless due to the gross negligence of Landlord, its
servants and employees), including but not limited to reasonable attorneys' fees
and other legal expenses.

                   23.2.    Neither Tenant nor any partner, shareholder or
trustee in Tenant shall be held responsible for, and each is hereby expressly
relieved from, any and all liability by reason of any injury, loss or damage to
any person or property in or about Landlord's Control Area (as defined in
Article 52 below), due to any cause whatsoever, or arising from the acts within
Tenant's Control Area of Landlord's cleaning personnel or Landlord's building
engineers, except for liability arising from Tenant's use of the roof, garage
and other facilities in Landlord's Control Area permitted pursuant to Articles
9.1.3 and 15.1, and whether the loss, any injury or damage be

                                       32
<PAGE>

to the person or property of Landlord, or any other person, unless due to the
gross negligence of Tenant, its servants or employees. Landlord further agrees
to indemnify, defend and save Tenant harmless from and against all claims by any
person made on account of such injury, loss or damage (unless due to the gross
negligence of Tenant, its servants or employees), including but not limited to
reasonable attorneys' fees and other legal expenses.

         24.       Condemnation.

                   24.1.    If the whole or a substantial part of the
Centerpointe I Building is taken or condemned for a public or quasi-public use
under any statute or by right of eminent domain by any competent authority or
sold in lieu of such taking or condemnation, such that in the opinion of
Landlord the Centerpointe I Building is not economically operable as before
without substantial alteration or reconstruction, this Lease shall automatically
terminate on the date that the right to possession shall vest in the condemning
authority (the "Taking Date"), with Rent being adjusted to said Taking Date, and
Tenant shall have no claim against Landlord for the value of any unexpired term
of this Lease. Tenant shall have no claim against Landlord and no claim or right
to any portion of any amount that may be awarded as damages or paid as a result
of any taking, condemnation or purchase in lieu thereof, except for moving
expenses, if any, which may be separately awarded to tenants under Virginia or
federal law to the extent that such award does not reduce the amount to be
awarded or paid to Landlord; all other rights of Tenant to any award are hereby
assigned by Tenant to Landlord. If the whole or a substantial part of the
Centerpointe II Premises is taken or condemned for a public or quasi-public use
under any statute or by right of eminent domain by any competent authority or
sold in lieu of such taking or condemnation, such occurrence shall be treated as
though a casualty had occurred to the Centerpointe II Premises and Landlord had
elected not to rebuild or restore the Centerpointe II Premises, as described in
Article 22.1 above.

                   24.2.    If any part of the Premises is so taken or
condemned, this Lease shall automatically terminate as to the portion of the
Premises so taken or condemned, as of the Taking Date, and this Lease shall
continue in full force as to the remainder of the Premises, with Rent abating
only to the extent of the Premises so taken or condemned.

                   24.3.    In the event of any temporary eminent domain taking
of the Premises or any part thereof for temporary use, this Lease shall not be
affected in any manner, the Term shall not be reduced, and the Tenant shall
continue to pay in full the Base Rent, Additional Rent and all other sums of
money and charges in this Lease reserved and provided to be paid by Tenant.
Tenant shall be entitled to receive for itself such portion of any eminent
domain award made for such temporary use with respect to the period of the
taking which is within the Term; provided that if such temporary taking shall
remain in full force at the expiration or earlier termination of this Lease, the
award shall be apportioned between Landlord and Tenant in proportion to the
respective portions of the period of temporary taking which falls within the
Term and which falls outside the Term.

         25.       Holding Over.

                                       33
<PAGE>

                   25.1.    If Tenant or any person claiming through Tenant
shall continue to occupy the Premises after the expiration or earlier
termination of the Term or any renewal thereof without Landlord's written
consent, then Landlord shall be entitled to recover from Tenant compensation for
such use and occupancy at a rate per month equal to (i) 150% of the annual Base
Rent plus (ii) 1/12 of the annual Additional Rent which would have been payable
had this Lease been renewed for a period of 12 full calendar months following
such expiration or earlier termination, on the terms and conditions in effect
immediately prior thereto. Neither Landlord's demand nor Landlord's receipt of
the aforesaid compensation for use and occupancy shall be deemed to provide
Tenant with any right to any use, occupancy or possession of the Premises for
any period beyond which such compensation has been demanded and paid.

                   25.2.    The provisions of this Article 25 shall not be
deemed to limit or constitute a waiver of any other rights of remedies of
Landlord provided herein or at law.

         26.       Covenant of Quiet Enjoyment. Landlord covenants that Tenant,
on paying the Rent and all other charges or payments herein reserved and on
keeping, observing and performing all the other terms, covenants, conditions,
provisions and agreements herein contained on the part of Tenant to be kept,
observed and performed, shall, during the Term, peaceably and quietly have, hold
and enjoy the Premises subject to the terms, covenants, conditions, provisions
and agreements hereof.

         27.       Relocation of Tenant.  Intentionally Omitted.

         28.       Condition of Premises. The taking of possession of each
segment of the Premises by Tenant shall be conclusive evidence, as against
Tenant, that each such segment of the Premises was in good and satisfactory
condition at the time such possession was so taken, subject to (i) completion of
any Base Building Modifications set forth on Exhibit "B" that have not been
completed by the date of delivery of any segment of the Premises, (ii) latent
defects, provided that Tenant so notifies Landlord within one (1) year-of the
Lease Commencement Date, as to the Initial Space, and within one (1) year of the
applicable Subsequent Lease Commencement Date, as to Subsequent Space, or (iii)
defects other than latent defects identified by Tenant in a notice given to
Landlord within thirty (30) days of the Lease Commencement Date, as to the
Initial Space, and within thirty (30) days of any applicable Subsequent Lease
Commencement Date, as to Subsequent Space.

         29.       No Third Party Beneficiaries. Notwithstanding anything to the
contrary contained herein, no provision of this Lease is intended to benefit any
party other than the signatories hereto and their permitted heirs, personal
representatives, successors and assigns, and no provision of this Lease shall be
enforceable by any other party.

         30.       Transfer of Landlord's Interest. In the event of any sale or
other conveyance or transfer of Landlord's interest in a Building or the
Buildings, the transferor shall be and hereby is entirely free and relieved of
all covenants and obligations of Landlord hereunder prior to the date of
transfer as to the Building or Buildings transferred, provided that the
transferee at any such sale or conveyance or transfer (subject to the limitation
of Landlord's liability in Article 19 of this Lease) shall have assumed and
agreed in a written agreement with Landlord to carry out any and

                                       34
<PAGE>

all covenants and obligations of Landlord hereunder arising or continuing from
and after the date of transfer.

         31.       Default; Landlord's Remedies.

                   31.1.    Defaults. If any of the following shall occur, such
occurrence shall constitute a default (which term, unless expressly noted
otherwise in this Lease, shall refer only to the circumstance that exists after
the giving of any notice and the expiration of any cure period provided for
herein) hereunder:

                   31.1.1.  Tenant does not pay in full when due any installment
of Rent or any other charge or payment whether or not herein included as Rent,
and such failure continues for ten (10) days after written notice from Landlord
specifying such failure, provided, however, that Landlord shall not be required
to give, and Tenant shall not be entitled to the benefit of, any such notice or
grace period more than two (2) times in any twelve (12) month period for late
payments of Monthly Installments of Base Rent and Additional Rent,

                   31.1.2.  Tenant violates or fails to perform or otherwise
breaks any covenant, agreement or condition herein contained or any other
obligation of Tenant to Landlord, and such violation or failure continues for
thirty (30) days after written notice from Landlord specifying such violation or
failure (or such longer period, as may be necessary if such violation or failure
cannot reasonably be cured within said thirty (30) day period but Tenant is
diligently and in good faith pursuing such cure and such violation or failure is
reasonably capable of a cure i as determined in Landlord's reasonable judgment),

                   31.1.3.  Tenant becomes the subject of commencement of an
involuntary case under the federal bankruptcy law as now or hereafter
constituted, or there is filed a petition against Tenant seeking reorganization,
arrangement, adjustment or composition of or in respect of Tenant under the
federal bankruptcy law as now or hereafter constituted, or under any other
applicable federal or state bankruptcy, insolvency, reorganization or other
similar law, or seeking the appointment of a receiver, liquidator or assignee,
custodian, trustee, sequestrator (or similar official) of Tenant or any
substantial part of its property, or seeking the winding-up or liquidation of
its affairs and such involuntary case or petition is not dismissed within 90
days after the filing thereof, or if Tenant commences a voluntary case or
institutes proceedings to be adjudicated a bankrupt or insolvent, or consents to
the institution of bankruptcy or insolvency proceedings against it, under the
Federal bankruptcy laws as now or hereafter constituted, or any other applicable
Federal or state bankruptcy or insolvency or other similar law, or consents to
the appointment of or taking possession by a receiver or liquidator or assignee,
trustee, custodian, sequestrator (or other similar official) of Tenant or of any
substantial part of its property, or makes any assignment for the benefit of
creditors or admits in writing its inability to pay its debts generally as they
become due or fails to generally pay its debts as they become due or if Tenant
or its stockholders or Board of Directors or any committee thereof takes any
corporate action in furtherance of any of the foregoing, then

                                       35
<PAGE>

                   31.2.    Remedies.  In the event of any such default set
forth in Article 31.1 above, and, at the sole option of Landlord, Landlord may
pursue any one or more of the following remedies:

                   31.2.1.  Tenant's right of possession shall thereupon cease
and terminate, and to the extent permitted by law Landlord shall be entitled to
the possession of the Premises and to reenter the same without demand of rent or
demand of possession of said Premises and may forthwith proceed to recover
possession of the Premises by process of law, any notice to quit being hereby
expressly waived by Tenant. In the event of such re-entry by process of law,
Tenant nevertheless agrees to remain answerable for any and all damage,
deficiency or loss of Rent which Landlord may sustain by such re-entry,
including reasonable attorney's fees and court costs. If, under the provisions
hereof, seven (7) days summons or other applicable summary process shall be
served, and a compromise or settlement therefor shall be made, such action shall
not be constituted as a waiver of any breach of any covenant, condition or
agreement herein contained. No waiver of any breach of any covenant, condition
or agreement, herein contained, on one or more occasions shall operate as a
waiver of the covenant, condition or agreement itself, or of any subsequent
breach thereof. No provision of this Lease shall be deemed to have been waived
by Landlord unless such waiver shall be in writing signed by Landlord.

                   31.2.2.  Should this Lease be terminated before the
expiration of the Term of this Lease by reason of Tenant's default, the Premises
may be relet by Landlord for such rent and upon such terms as are reasonable
under the circumstances. If the full Rent reserved under this Lease (and any of
the costs, expenses or damages indicated below) shall not be realized by
Landlord, Tenant shall be liable for all damages sustained by Landlord,
including, without limitation, deficiency in Rent, reasonable attorneys' fees,
other reasonable collection costs, reasonable brokerage fees, and reasonable
expenses of placing the Premises in first-class rentable condition. Landlord, in
putting the Premises in good order or preparing the same for re-rental, may, at
Landlord's option, make such alterations, repairs, or replacements in the
Premises as Landlord, in Landlord's sole judgment, considers advisable and
necessary for the purpose of reletting the Premises, and the making of such
alterations, repairs, or replacements shall not operate or be construed to
release Tenant from liability hereunder as aforesaid. Landlord shall in no event
be liable in any way whatsoever for failure to relet the Premises, or in the
event that the Premises are relet, for failure to collect the rent thereof under
such reletting. In no event shall Tenant be entitled to receive any excess, if
any, of such net rent collected over the sums payable by Tenant to Landlord
hereunder.

                   31.2.3.  Any damage or loss of Rent sustained by Landlord may
be recovered by Landlord, at Landlord's option, at the time of the reletting, or
in separate actions, from time to time, as said damage shall have been
ascertained by successive relettings, or, at Landlord's option, may be deferred
until the expiration of the Term of this Lease (in which event Tenant hereby
agrees that the cause of action shall not be deemed to have accrued until the
date of expiration of said Term). The provisions contained in this Article
31.2.3 shall be in addition to and shall not prevent the enforcement of any
claim Landlord may have against Tenant for anticipatory breach of the unexpired
Term of this Lease. All rights and remedies of Landlord under this Lease shall
be

                                       36
<PAGE>

cumulative and shall not be exclusive of any other rights and remedies provided
to Landlord under applicable law.

                   31.2.4.  If under the provisions hereof Landlord shall
institute proceedings and a compromise or settlement thereof shall be made, the
same shall not constitute a waiver of any covenant, rule or regulation herein
contained nor of any of Landlord's rights hereunder. No waiver by Landlord of
any breach of any covenant, condition, agreement, rule or regulation itself, or
of any subsequent breach thereof.

                   31.2.5.  If, prior to the Rent Commencement Date, Tenant
notifies Landlord of or otherwise unequivocally demonstrates an intention to
repudiate this Lease, Landlord may, at its option, consider such anticipatory
repudiation a breach of this Lease. In such event, in addition to Landlord's
other remedies hereunder, Landlord may retain all Rent paid upon execution of
the Lease and the security deposit, if any, to be applied to damages of Landlord
incurred as a result of such repudiation, including without limitation
reasonable attorneys' fees, brokerage fees, costs of reletting, loss of Rent,
etc. and Landlord shall be entitled to recover all or any portion of the
Concession Fund theretofore disbursed to Tenant hereunder (which, when
collected, shall be credited against Tenant's other liabilities hereunder), and
Tenant shall indemnify, defend and hold Landlord harmless from and against the
claims of any contractors or materialmen performing the Tenant Work.

                   31.2.6.  If the Premises shall be deserted or vacated by
Tenant for thirty (30) consecutive days or more without notice to Landlord, and
Tenant shall have failed to make the current Rent payment, the Premises may be
deemed abandoned. Landlord may consider Tenant in default under this Lease and
may pursue all remedies available to it under this Lease or at law, including
the following:

                            (a)      If Tenant abandons the Premises as defined
above, Landlord may, at its option, enter into the Premises without being liable
for any prosecution therefor or for damages by reason thereof. In addition to
any other remedy, Landlord, as agent of Tenant, may relet the whole or any part
of the Premises for the whole or any part of the then unexpired Lease Term. For
the purposes of such reletting, Landlord may make any alterations or
modifications of the Premises considered desirable in its sole judgment.

                            (b)      If Tenant abandons the Premises as defined
above, any property that Tenant leaves on the Premises shall be deemed to have
been abandoned and may either be retained by Landlord as the property of
Landlord or may be disposed of at public or private sale in accordance with
applicable law as Landlord sees fit. The proceeds of any public or private sale
of Tenant's property, or the then current fair market value of any property
retained by Landlord, shall be applied by Landlord against (i) the expenses of
Landlord for removal, storage or sale of the property; (ii) the arrears of Rent
or future Rent payable under this Lease; and (iii) any other damages to which
Landlord may be entitled hereunder.

                            (c)      If Tenant abandons the Premises, as defined
above, Landlord may, upon presentation of evidence of a claim valid upon its
face of ownership or of a security interest

                                       37
<PAGE>

in any of Tenant's property abandoned in the Premises, turn over such property
to the claimant with no liability to Tenant.

                   31.2.7.  Landlord may (but shall not be obligated to do so),
in addition to any other rights it may have in law or equity, following the
delivery of notices prescribed by Article 31.1 above, cure such default on
behalf of Tenant, and Tenant shall reimburse Landlord upon demand for all
reasonable costs incurred by Landlord in curing such default, including, without
limitation, reasonable attorneys' fees and other legal expenses, together with
interest thereon at the Lease Interest Rate, which costs and interest thereon
shall be deemed Additional Rent hereunder.

         32.       Remedies Cumulative. All remedies available to Landlord
hereunder and at law and in equity shall be cumulative and concurrent. No
termination of this Lease nor taking or recovering possession of the Premises
shall deprive Landlord of any remedies or actions against Tenant for Rent, for
charges or for damages for the breach of any covenant, agreement or condition
herein contained, nor shall the bringing of any such action for Rent, charges or
breach of covenant, agreement or condition, nor the resort to any other remedy
or right for the recovery of Rent, charges or damages for such breach be
construed as a waiver or release of the right to insist upon the forfeiture and
to obtain possession. No reentering or taking possession of the Premises, or
making of repairs, alterations or improvements thereto, or reletting thereof,
shall be construed as an election on the part of Landlord to terminate this
Lease unless written notice of such election be given by Landlord to Tenant. The
failure of Landlord to insist upon strict and/or prompt performance of the
terms, agreements, covenants and conditions of this Lease or any of them, and/or
the acceptance of such performance thereafter shall not constitute or be
construed as a waiver of Landlord's right to thereafter enforce the same
strictly according to the terms thereof in the event of a continuing or
subsequent default.

         33.       Expenses of Enforcement. Each party shall pay upon demand all
of the other party's costs, charges and expenses, including the reasonable fees
and out-of-pocket expenses of counsel, agents and others, incurred in any
litigation, negotiation or transaction in which the defaulting party causes the
other without the other's fault, to become involved or concerned.

         34.       Nonwaiver. No waiver of any provision of this Lease shall be
implied by any failure of either party to enforce any remedy allowed for the
violation of such provision, even if such violation is continued or repeated,
and no express waiver shall affect any provision other than the one(s) specified
in such waiver and only for the time and in the manner specifically stated. No
receipt of monies by Landlord from Tenant after the termination of this Lease
shall in any way alter the length of the Term or of Tenant's right of possession
hereunder or after the giving of any notice shall reinstate, continue or extend
the Term or affect any notice given to Tenant prior to the receipt of such
moneys, it being agreed that after the service of notice or the commencement of
a suit or after final judgment for possession of the Premises, Landlord may
receive and collect any Rent due, and the payment of said Rent shall not waive
or affect said notice, suit or judgment.

         35.       Subordination.

                   35.1.    Subject to the satisfaction of the conditions of
Article 58 below, this Lease shall be subject and subordinate at all times to
the lien of any mortgage, deed of trust and/or other encumbrance heretofore or
hereafter placed by Landlord upon the Premises or the Property and of

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<PAGE>

all renewals, modifications, consolidations, replacements and extensions thereof
(all of which are hereinafter referred to collectively as a "Mortgage"), all
automatically and without the necessity of any further action on the part of
Tenant to effectuate such subordination. Tenant shall, at the request of any
person who may acquire Landlord's estate by foreclosure (or transfer in lieu of
foreclosure), attorn to such person, and shall execute, acknowledge and deliver,
upon demand by Landlord or any mortgage holder or its assignee, but in no event
later than fifteen (15) days after such demand, such further reasonable
instruments evidencing such subordination, and such further reasonable
instruments evidencing such attornment obligation, as shall be desired by such
Mortgage holder or its assignee.

                   35.2.    Anything contained in the foregoing provisions of
this Article 35 to the contrary notwithstanding, any such holder may at any time
subordinate, in whole or in part, its Mortgage to the operation and effect of
this Lease, without the necessity of obtaining Tenant's consent thereto, by
giving notice of the same in writing to Tenant, and thereupon this Lease shall
be deemed to be prior to such Mortgage without regard to their respective dates
of execution, delivery and/or recordation, and in that event, such holder shall
have the same rights with respect to this Lease as though this Lease were
executed, delivered and recorded prior to the execution and delivery of such
Mortgage.

                   35.3.    No person acquiring Landlord's estate by foreclosure
or transfer in lieu of foreclosure shall have any personal liability hereunder
or any liability whatsoever for the acts of the Landlord prior to any such
transfer or any liability for any deposits made by Tenant hereunder unless such
deposits have been transferred to such party; provided, however, that such party
shall have the liability to perform all of the Landlord's duties and obligations
arising or continuing thereafter, if any, that have not been performed as of the
date of transfer.

         36.       Paramount Lease. Subject to the satisfaction of the terms of
Article 58 below, if Landlord is or becomes lessee of a Building or the
Buildings or the land upon which they stand, then Tenant agrees that Tenant's
possession shall be that of a subtenant and subordinate to the interest of
Landlord's lessor, its heirs, personal representatives, successors and assigns
(such lessor and other persons being hereinafter collectively referred to as the
"Overlessor") without the necessity of any further action on the part of Tenant
to effectuate such subordination (provided that such change in status does not
affect any of Tenant's rights or Landlord's obligations under this Lease), but
notwithstanding the foregoing, if Landlord's tenancy shall terminate either by
expiration, forfeiture or otherwise, then, if Overlessor shall so request,
Tenant shall attorn to Overlessor and recognize Overlessor as Tenant's landlord
upon the terms and conditions of this Lease for the balance of the Term hereof
and any extensions or renewals hereof. Tenant shall execute, acknowledge and
deliver, upon demand by Landlord or any Overlessor, such further customary and
reasonable instruments evidencing such subordination of Tenant's right, title
and interest under this Lease to the interests of Overlessor, and such further
customary and reasonable instruments of attornment, as shall be desired by such
Overlessor. Landlord represents and warrants that the Property is not currently
subject to any ground lease or Overlease.

         37.       Legal Proceedings. It is mutually agreed by and between
Landlord and Tenant that (a) they hereby waive trial by jury in any action,
proceeding or counter-claim brought by either of

                                       39
<PAGE>

the parties hereto against the other on any matter whatsoever arising out of or
in any way connected with this Lease, the relationship of Landlord and Tenant,
Tenant's use or occupancy of the Premises or claim of injury or damage, and (b)
in any action against Landlord by Tenant, or against Tenant by Landlord, the
reasonable legal fees of the prevailing party will be paid by the other party to
the action. The parties hereto consent to the jurisdiction of the courts of the
Commonwealth of Virginia and of the United States District Court of Virginia in
connection with any action, suit or proceeding arising out of or relating to
this Lease, and agree that venue shall lie only in said courts.

         38.       Interpretation.

                   38.1.    Gender; Plural Terms; Persons.  The masculine (or
neuter) pronoun and the singular number shall include the masculine, feminine
and neuter genders and the singular and plural numbers. A reference to person
shall mean a natural person, a trustee, a corporation, a partnership and any
other form of legal entity. All references in the singular or plural number
shall be deemed to have been made, respectively, in the plural or singular
number as well, as the context may require.

                   38.2.    Exhibits.  Each and every document or other writing
which is referred to herein as being attached hereto or is otherwise designated
herein as an exhibit hereto is hereby made a part hereof.

                   38.2.1.  Captions.  The captions of Articles, sections,
subsections and the Table of Contents are for convenience only; they are not
intended to indicate all of the subject matter in the text and they shall not be
deemed to limit, construe, affect or alter the meaning of any provisions of this
Lease and are not to be used in interpreting this Lease or for any other purpose
in the event of any controversy.

         39.       Severability. If any provision contained in this Lease shall,
to any extent, be invalid or unenforceable, the remainder of this Lease (and the
application of such provision to persons or circumstances, if any, other than
those in respect of which it is invalid or unenforceable) shall not be affected
thereby, and each and every other provision of this Lease shall be valid and
enforceable to the fullest extent permitted by law.

         40.       Notices. All notices required to be given by Landlord to
Tenant shall be sufficiently given by overnight courier service delivery against
written receipt or signed proof of delivery, or mailing the same by registered
or certified mail, return receipt requested, to Tenant's Address or to such
other person or persons and address or addresses as Tenant may from time to time
designate in writing and deliver to Landlord in accordance with this Article.
Notices given by Tenant to Landlord shall be sufficiently given by registered or
certified mail, return receipt requested, overnight express delivery service or
by courier service delivery against written receipt or signed proof of delivery,
to Landlord at Landlord's Address or to such other person and address as
Landlord may from time to time designate in writing and deliver to Tenant in
accordance with this Article. Notices may be given on behalf of either party by
its counsel.

                                       40
<PAGE>

         41.       No Representation by Landlord. Landlord and Landlord's agents
have made no representation, agreements, conditions, warranties, understandings,
or promises, either oral or written, other than as herein set forth, with
respect to the Lease, Buildings, Property, or Premises, or otherwise.

         42.       Whole Agreement. This Lease, the exhibits, and any riders
attached hereto and forming a part hereof set forth all of the promises,
agreements, conditions, warranties, representations and understandings between
Landlord and Tenant relative to the Premises and this leasehold. No alteration,
amendment, modification, waiver, understanding or addition to this Lease shall
be binding upon Landlord or Tenant unless reduced to writing and signed by
Landlord and Tenant or by a duly authorized agent of Landlord or Tenant
empowered by a written authority signed by Landlord and/or Tenant (as the case
may be).

         43.       Security Deposit.  Intentionally Omitted.

         44.       Real Estate Broker. Landlord and Tenant each represent and
warrant to the other that it has dealt with no broker, agent or other
intermediary in connection with this Lease other than Julien J. Studley, Inc.
and Cushman & Wakefield of Virginia, and that insofar as it knows, no other
broker, agent or other intermediary negotiated this Lease or introduced Tenant
to Landlord or brought the Buildings to Tenant's attention for the lease of
space therein. Tenant recognizes Cushman & Wakefield of Virginia as its broker
of record for the Term of this Lease and authorizes Joshua Realty Corporation to
pay the commissions to Cushman & Wakefield of Virginia during the Term of this
Lease pursuant to an agreement of even date herewith and Landlord agrees that
Joshua Realty Corporation, as Landlord, shall be responsible for any commissions
payable to Julien J. Studley, Inc., with respect to this Lease, pursuant to a
separate agreement of even date herewith. Each party agrees to indemnify, defend
and hold the other and its partners, employees, agents, their officers and
partners, harmless from and against any claims made by any broker, agent or
other intermediary other than Julien J. Studley, Inc. and Cushman & Wakefield of
Virginia, with respect to a claim for broker's commission or fee or similar
compensation brought by any person in connection with this Lease, provided that
the indemnified party has not in fact retained such broker, agent or other
intermediary.

         45.       Inability to Perform. If Landlord or Tenant is delayed or
prevented from performing any of its obligations under this Lease by reason of
strike, labor troubles, or any cause whatsoever beyond its control, the period
of such delay or prevention shall be deemed added to the time herein provided
for the performance of any such obligation.

         46.       Corporate Entities. If Tenant is a corporation, each person
executing this Lease on behalf of Tenant hereby covenants and warrants that:
Tenant is a duly formed corporation qualified to do business in the state in
which the Premises is located; all Tenant's franchise and corporate taxes have
been paid to date; and such persons are duly authorized by such corporation to
execute and deliver this Lease on behalf of the corporation. Each person
executing this Lease on behalf of Landlord hereby covenants and warrants that:
Landlord is a duly formed corporation qualified to do business in the state in
which the Premises is located; all Landlord's franchise and

                                       41
<PAGE>

corporate taxes have been paid to date; and such persons are duly authorized by
such corporation to execute and deliver this Lease on behalf of the corporation.

         47.       Recordation. At the time of execution of this Agreement,
Landlord and Tenant shall execute and acknowledge, in recordable form, for
notice and recording purposes only, a Memorandum of this Agreement, it being
expressly agreed that such Memorandum shall not supersede, add to or change this
Lease. The form of Memorandum is attached hereto as Exhibit "J" and Tenant may
cause the Memorandum to be recorded in the appropriate office for recording in
Fairfax County at Tenant's sole expense. Tenant covenants to execute and deliver
a termination of Memorandum upon the termination of this Lease, and Tenant
hereby appoints Landlord its attorney-in-fact to file any instrument to remove
or discharge from record any such Memorandum.

         48.       Time. Time is of the essence of this Lease and all of its
provisions.

         49.       Applicable Law. This Lease shall in all respects be governed
by the laws of the Commonwealth of Virginia.

         50.       Defined Terms. As used in this Lease, the following terms
have the meaning as set forth below, respectively:

                   50.1.    Affiliate.  Any corporation which is controlled by,
controlling, or under common control with Tenant. As used herein the term
"control" shall mean possession of the power, directly or indirectly, to vote
more than fifty percent (50%) of the voting securities having the ordinary power
for the election of directors.

                   50.2.    Buildings: The physical structures located at 4050
Legato Road and 4000 Legato Road, Fairfax, Virginia.

                   50.3.    Holidays: The following holidays:

                   50.3.1.  For the Centerpointe I Building

                   New Year's Day
                   Martin Luther King Jr. Day (in even-numbered years)
                   Washington's (President) Birthday
                   Memorial Day
                   Independence Day
                   Labor Day
                   Columbus Day (in odd-numbered years)
                   Thanksgiving Day
                   Day After Thanksgiving
                   Christmas Day

                   50.3.2.  For the Centerpointe II Building:

                   New Year's Day
                   Martin Luther King Jr. Day
                   Washington's (President) Birthday

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<PAGE>

                   Memorial Day
                   Independence Day
                   Labor Day
                   Columbus Day
                   Veterans Day
                   Thanksgiving Day
                   Christmas Day

                   50.4.    HVAC Off-Hours Rate: For the Centerpointe I
Building, a rate which shall include only Landlord's actual labor costs and the
reasonable cost for additional wear and tear of Landlord's equipment. For the
Centerpointe II Building, a charge per floor equal to $45.00 per hour, and
$54.00 per hour on Holidays (with a flat rate of $25.00 per hour payable for
each additional floor), with a two (2) hour minimum, subject to adjustment in
accordance with any increases in Landlord's actual labor costs and the
reasonable cost of additional wear and tear of Landlord's equipment.

                   50.5.    Landlord: The Landlord named on page 1 of this Lease
and any subsequent owner of such Landlord's interest in the Buildings, as well
as their respective heirs, personal representatives, successors and assigns, all
subject to the provisions of Article 19.

                   50.6.    Lease Interest Rate: The lesser of (A) the Prime
Rate in effect from time to time plus 3%, or, (B) the maximum amount or rate
that Landlord lawfully may charge Tenant in such circumstances, if such a
maximum exists.

                   50.7.    Lease Taxes: Any tax, assessment, levy or other
charge (other than any income tax or the Fairfax County BPOL gross receipts or
gross expenditure taxes) by any federal, state or local law now or hereafter
imposed directly or indirectly upon Landlord with respect to this Lease or the
value thereof, or upon the Tenant's use or occupancy of the Premises, or upon
the Base Rent, Additional Rent or any other sums payable under this Lease or
upon this transaction.

                   50.8.    Ordinary Business Hours: Monday through Friday,
inclusive, from 8:00 a.m. to 7:00 p.m., in the Centerpointe I Building, and from
8:00 a.m. to 6:00 p.m., in the Centerpointe II Building, and Saturdays from 8:00
a.m. to 1:00 p.m. in both Buildings, with Holidays excepted.

                   50.9.    Prime Rate: The reference rate of interest as
published in the Money Rates section of the Wall Street Journal from time to
time, or if such reference rate is discontinued, such comparable rate as
Landlord reasonably designates by written notice to Tenant.

                   50.10.   Property: The Buildings and the land owned by
Landlord upon which they stand, as more particularly described on Exhibit "HI'
attached hereto.

                   50.11.   Real Estate Taxes: All real estate taxes and
assessments, general or special, ordinary or extraordinary, foreseen or
unforeseen (other than Lease Taxes) assessed or imposed upon the Buildings
and/or the Property. If, due to a future change in the method of taxation, any
franchise, income, profit or other tax, however designated, shall be levied or
imposed in substitution, in whole or in part, for (or in lieu of) any tax or
increase in any tax which would otherwise be included within the

                                       43
<PAGE>

definition of Real Estate Taxes, then such other tax shall be deemed to be
included within Real Estate Taxes as defined herein. Any special assessments
which may be paid in installments shall be paid over the maximum number of
installments permitted without the imposition of any penalty. Except as provided
in the immediately-preceding sentence, Real Estate Taxes shall not include any
income, profit, franchise, capital stock, excise, estate, gift, succession,
transfer or recordation tax or levy.

                   50.12.   Rent: Additional Rent and Base Rent, collectively.

                   50.13.   Rentable Area of the Buildings: Deemed to be 203,630
square feet for each of the Centerpointe I Building and the Centerpointe II
Building.

                   50.14.   Rentable Area of the Premises: As set forth in
Article 1.1 hereof.

                   50.15.   Tenant: Each and every person hereinabove named as
Tenant on page 1 of this Lease and such persons' respective heirs, personal
representatives, successors and assigns, subject to the provisions of Article
14.7.

                   50.16.   Tenant's Proportionate Share:

                   50.16.1. As to the Centerpointe I Building, Tenant's
Proportionate Share shall be 100% ("Tenant's Centerpointe I Proportionate
Share").

                   50.16.2. As to the Centerpointe II Building, Tenant's
Proportionate Share shall be 18.85% ("Tenant's Centerpointe II Proportionate
Share"), which is derived by dividing the Rentable Area of the Centerpointe II
Premises by 203,630, which is the Rentable Area of the Centerpointe II Building.

         51.       Delivery for Examination. DELIVERY OF THE LEASE TO TENANT
SHALL NOT BIND LANDLORD IN ANY MANNER, AND NO LEASE OR OBLIGATIONS OF LANDLORD
OR TENANT SHALL ARISE UNTIL THIS INSTRUMENT IS SIGNED BY BOTH LANDLORD AND
TENANT AND DELIVERY IS MADE TO EACH.

         52.       Environmental Matters.

                   52.1.    Compliance with Law.  For purposes of this Article
52, Landlord and Tenant shall each be referred to as the "Responsible Party"
with regard to their respective "Control Areas". Tenant's "Control Area" shall
be the Centerpointe I Building (but does not include the Core Elements of the
Centerpointe I Building), and the portion of the Premises in the Centerpointe II
Building, (but does not include the Core Elements within the Centerpointe II
Building that fall within the Centerpointe II Premises) while Landlord's
"Control Area" shall be the Property, exclusive of (i) the Centerpointe I
Building (but including the "Core Elements" of the Centerpointe I Building), and
(ii) the portion of the Premises in the Centerpointe II Building (but including
the Core Elements within the Centerpointe II Building that fall within the
Premises). Each Responsible Party shall conduct, and cause to be conducted, all
operations and activity at its Control Area in compliance with, and shall in all
other respects applicable to such Control Area comply with, all applicable
present and future federal, state, municipal and other governmental statutes,
ordinances, regulations, orders, directives and other requirements, and all
present and

                                       44
<PAGE>

future requirements of common law, concerning the environment (hereinafter
collectively called "Environmental Statutes") including, without limitation, (i)
those relating to the generation, use, handling, treatment, storage,
transportation, release, emission, disposal, remediation or presence of any
material, substance, liquid, effluent or product, including, without limitation,
hazardous substances, hazardous waste or hazardous materials, (ii) those
concerning conditions at, below or above the surface of the ground and (iii)
those concerning conditions in, at or outside buildings. In addition, Landlord's
compliance obligation shall extend to matters existing at the Property
(including Tenant's Control Area) prior to the date hereof.

                   52.2.    Permits.  Each Responsible Party, in a timely
manner, with respect to its Control Area, shall obtain and maintain in full
force and effect all permits, licenses and approvals, and shall make and file
all notifications and registrations as required by Environmental Statutes, and
shall at all times comply with the terms and conditions of any such permits,
licenses, approvals, notifications and registrations.

                   52.3.    Documents.  Each Responsible Party shall provide to
the other party copies of the following, forthwith after each shall have been
submitted, prepared or received by the Responsible Party or any occupant of its
Control Area: (i) all applications and associated materials submitted to any
governmental agency relating to any Environmental Statute; (ii) all
notifications, registrations, reports and other documents, and supporting
information, prepared, submitted or maintained in connection with any
Environmental Statute; (iii) all permits, licenses, approvals, and amendments or
modifications thereof, obtained under any Environmental Statute; and (iv) any
correspondence, notice of violation, summons, order, complaint, or other
document received by such Responsible Party or any occupant of its Control Area
pertaining to compliance with or liability under any Environmental Statute.

                   52.4.    Operations.  Neither Responsible Party shall cause
or suffer or permit to occur in, on or under its Control Area any generation,
use, manufacturing, refining, transportation, emission, release, treatment,
storage, disposal, presence or handling of hazardous substances, hazardous
wastes or hazardous materials (as such terms are now or hereafter defined under
any Environmental Statute) or any other material, substance, liquid, effluent or
product now or hereafter regulated by any Environmental Statute (all of the
foregoing herein collectively called "Hazardous Substances"), except that
construction materials (other than asbestos or polychlorinated biphenyls),
office equipment, fuel and similar products (if contained in vehicles) and
cleaning solutions, and other maintenance materials that are or contain
Hazardous Substances may be used, generated, handled or stored in the Control
Area, provided such is incident to and reasonably necessary for the operation
of, maintenance of or conduct of business in the Control Area and is in
compliance with all Environmental Statutes and all other applicable governmental
requirements. Should any release of any Hazardous Substance occur at a Control
Area, the Responsible Party shall immediately contain, remove and dispose of,
from the Control Area such Hazardous Substances, and any material that was
contaminated by the release and to remedy and mitigate all threats to human
health or the environment relating to such release. When conducting any such
measures the Responsible Party shall comply with all Environmental Statutes.

                                       45
<PAGE>

                   52.5.    Indemnification.  Each Responsible Party hereby
agrees to indemnify and to hold harmless the other party hereto of, from and
against any and all expense, loss or liability suffered by the other party
hereto by reason of the Responsible Party's breach of any of the provisions of
this Article, including, but not limited to, (i) any and all expenses that the
indemnified party may incur in complying with any Environmental Statutes, (ii)
any and all costs that the indemnified party may incur in studying, assessing,
containing removing, remedying, mitigating, or otherwise responding to, the
unlawful release of any Hazardous Substance or waste at or from the other
party's Control Area, (iii) any and all costs for which the indemnified party
may be liable to any governmental agency for studying, assessing, containing,
removing, remedying, mitigating, or otherwise responding to, the unlawful
release of a Hazardous Substance or waste at or from the other party's Control
Area, (iv) any and all fines or penalties assessed, or threatened to be
assessed, upon the indemnified party by reason of a failure of the indemnifying
party to comply with any obligations, covenants or conditions set forth in this
Article, and (v) any and all legal fees and costs incurred by the indemnified
party in connection with any of the foregoing.

                   52.6.    General Compliance.  The provisions of this Article
52 shall not be construed as limiting in any respect the covenants and
obligations of either party hereunder. All covenants, obligations and
liabilities of Landlord and Tenant under this Article 52 shall survive the
expiration or other termination of this Lease.

         53.       Tenant's Remedies.

                   53.1.    If Landlord shall be in default in the performance
of any of its duties or obligations hereunder for fifteen (15) consecutive days
after written notice from Tenant (unless such default is not susceptible of cure
within fifteen (15) days in which event Landlord shall have failed to commence
curing such default within such fifteen (15) day period and diligently
prosecuted such cure until completion), and as a result thereof all or a
substantial portion of any floor is rendered untenantable, inaccessible,
incapable of use, or Tenant's use or enjoyment thereof is materially and
adversely affected, in addition to any other rights Tenant may have in law or
equity, Tenant may but shall not be obligated to cure such default on behalf of
Landlord. Landlord shall reimburse Tenant upon demand for all reasonable
out-of-pocket costs incurred by Tenant in curing such default, including,
without limitation, reasonable attorneys' fees and other legal expenses,
together with interest thereon at the Lease Interest Rate. Notwithstanding the
foregoing, Tenant shall not have any right in exercising its remedies under the
preceding sentence to make any repairs or modifications to areas outside the
Premises or to Building systems except those within and solely affecting the
Premises or those required to maintain direct access to the Premises or provide
services directly to the Premises (in any case in a manner which does not
materially adversely affect the Buildings or other tenants in the Centerpointe
II Building), or to provide any services for the benefit of any occupants of the
Buildings other than Tenant, or to retain any contractors or subcontractors to
perform such services which are not responsible contractors and subcontractors.
Tenant shall give written notice to Landlord prior to retaining any such
contractors or subcontractors of the identity of such contractors and
subcontractors.

                                       46
<PAGE>

                   53.2.    If the cure provided for under Article 53.1 above
involves a payment by Tenant for Landlord's account, then Tenant may set off the
amount of such payment (and the interest provided for in Article 53.1 above)
against any Rent payable by Tenant hereunder except for payments of Base Rent,
unless (a) Landlord's default is a failure to pay any portion of the Concession
Fund when the same is due, in which event Tenant shall have a right of set off
as against Base Rent and Additional Rent in the amount of any portion of the
Concession Fund that was not paid when due, together with interest at the Lease
Interest Rate from the due date until the date of set off, or (b) the set off
right arises in the last year of the Term or in the last year of any Renewal
Period, in which event Tenant shall have a right of set off against Base Rent
and Additional Rent. Notwithstanding anything else herein to the contrary,
however, in the event Landlord disputes that its has the obligation to reimburse
Tenant as aforesaid, Tenant shall not have any right of set off against the
amount thereof against Rent until such time that a court of competent
jurisdiction has entered a judgment which provides that Landlord was in fact
obligated to make such payment or Landlord is determined to have had such
obligation pursuant to the arbitration provisions set forth in Article 65 of
this Lease. The survival of Tenant's set off rights, if any, in the event of a
foreclosure or other enforcement of a mortgage, deed of trust or ground lease
shall be governed by Article 58 below.

         54.       Extension Option.

                   54.1.    So long as Tenant is not in default under this
Lease, Tenant shall have an option to extend the Term of this Lease for two (2)
additional periods of five (5) years each (each a "Renewal Period"). The option
for each such additional 5-year Renewal Period term may be exercised by Tenant
only by written notice (the "Extension Exercise Notice") given to Landlord not
later than the date which is at least fifteen (15) months prior to the
expiration of the Term, in the case of the first 5-year option, and at least
fifteen (15) months prior to the expiration of the first Renewal Period (each an
"Option Exercise Date"), in the case of the second Renewal Period. In the event
that Tenant exercises the option to extend the Term in accordance with the
provisions hereof, the Term shall be extended accordingly. Tenant's extension
option for the first Renewal Period shall be for a minimum of fifty percent
(50%) of the Rentable Area of the Centerpointe I Building in a contiguous block
of space and shall be for no less than one-half of any particular floor.
Tenant's extension option for the second Renewal Period shall be for one hundred
percent (100%) of the space for which Tenant exercised the extension option
during the first Renewal Period. Upon the commencement of each Renewal Period,
Landlord shall grant to Tenant a reasonable refurbishment allowance in such
amount as may be mutually agreed to by Landlord and Tenant, which amount shall
be agreed to in conjunction with, and as a component of, the determination of
"Market Rental Value", as described below. Except as stated below in this
Article, all of the terms and conditions of this Lease in effect immediately
prior to the respective Renewal Period shall equally pertain in all respects to
the respective Renewal Period. All references in this Lease to the Term of this
Lease shall be construed to include the applicable Renewal Period, unless the
context clearly indicates that another meaning is intended. Tenant shall not
have the right to exercise the extension option for the second Renewal Period
unless Tenant had previously exercised the extension option for the first
Renewal Period.

                                       47
<PAGE>

                   54.2.    Annual Base Rent during the first Renewal Period
shall be the greater of (i) ninety percent (90%) of the Market Rental Value of
the Premises (as defined and determined below) for that period or (ii) the
then-current rate of Base Rent, net of Base Year Operating Expenses and Base
Year Real Estate Taxes; provided, however, that if the then-current Base Rent,
net of Base Year Operating Expenses and Base Year Real Estate Taxes is greater
than 100% of Market Rental Value, the annual Base Rent shall be 100% of Market
Rental Value. Annual Base Rent for the second Renewal Period shall be one
hundred percent (100%) of the Market Rental Value of the Premises. The
determination of Market Rental Value shall account for the fact that Base Year
operating Expenses and Base Year Real Estate Taxes for each Renewal Period shall
be the Operating Expenses and Real Estate Taxes incurred by Landlord during the
calendar year in which the applicable Renewal Period commences.

                   54.3.    "Market Rental Value" of the Premises for the
Renewal Periods shall be determined by Landlord and Tenant not later than thirty
(30) days after Landlord's receipt of the respective Extension Exercise Notice
("Negotiation Period"). if Landlord and Tenant cannot agree as to Market Rental
Value of the Premises prior to the end of the Negotiation Period, then Tenant
may deliver written notice to Landlord within ten (10) days after the expiration
of the Negotiation Period rescinding Tenant's Extension Exercise Notice, in
which event this Lease shall expire upon the last day of the then-current Term.
If Tenant does not deliver such rescission notice within ten (10) days after the
expiration of the Negotiation Period, then Market Rental Value shall be
determined as follows:

                   54.3.1.  Landlord and Tenant shall each, within fifteen (15)
days after the expiration of the Negotiation Period, select a broker, each of
whom shall be a Virginia-licensed real estate broker with at least ten (10)
years experience in the Fairfax/Fair Oaks office market, who shall determine the
Market Value Rental. The brokers shall be instructed to submit their written
determinations of the Market Rental Value of the Premises to Landlord and Tenant
within thirty (30) days after their appointment. In the event that higher of the
two determinations exceeds the lower of the two determinations by less than five
percent (5%), the Market Rental Value shall be the average of such
determinations. If the higher of the two determinations exceeds the lower of the
two determinations by five percent (5%) or more, the brokers shall, within ten
(10) days, appoint a third broker with similar qualifications to make such
determination of the Market Rental Value in accordance with the foregoing
limitations. In the event that the two brokers cannot agree as to the selection
of the third broker, either party may request that the President of the
Washington Area Commercial Brokers Council appoint the third broker. The third
broker shall be instructed to complete the appraisal procedure and to submit a
written determination of the Market Rental Value to Landlord and Tenant within
thirty (30) days after such broker's appointment. The rental rate that shall be
binding upon Landlord and Tenant as the Market Rental Value shall be the mean of
the two closest determinations; provided, however, that (i) if any determination
is agreed upon by any two of the brokers, then Market Rental Value shall equal
such agreed-upon determination, and (ii) if any determination is equidistant
from the other two determinations, then Market Rental Value shall equal such
middle determination. Landlord and Tenant shall each bear the costs of their
respective brokers. The expenses of the third broker shall be borne one-half
(1/2) by Landlord and one-half (1/2) by Tenant.

                                       48
<PAGE>

                   54.3.2.  For purposes of this Article, the term "Market
Rental Value" means the fair market rental rate per square foot of the Rentable
Area of the Premises that would be agreed upon between a landlord and a tenant
of similar creditworthiness entering into a new lease in comparable buildings
(with structured or below-grade parking amenities) of comparable age as the
Buildings, assuming the following: (A) the landlord and tenant are typically
motivated; (B) the landlord and tenant are well informed and well advised and
each is acting in what it considers its own best interests; (C) in the event the
Premises have been destroyed or damaged by fire or other casualty, they have
been fully restored; (D) the Premises are to be let with vacant possession and
subject to the provisions of this Lease for a term commensurate with the
respective Renewal Period. Market Rental Value shall take into account market
rents then being charged for leases of comparable square footage and comparable
space in other similar office buildings in comparable locations, rent escalation
provisions then prevailing, rental abatements, build-out allowances and other
concessions then customarily granted, any savings in brokerage commissions by
Landlord, and other terms customarily agreed to in market leases entered into at
such times.

         55.       Signage.

         Tenant shall have the right to install two illuminated signs on the top
of the Centerpointe I Building identifying Tenant's corporate name or logo. The
signs must be of design, material, size, color, location and construction
methods acceptable and approved by Landlord prior to installation, which
approval shall not be unreasonably withheld, delayed or conditioned. In
addition, the signs shall be built and installed in accordance with all
applicable local county and state codes. Subject to the signage rights of
existing tenants (including how those prior rights impact on the total allowable
signage for the Property), Tenant shall have the right to install a monument
sign at the approach to the Centerpointe I Building so long as such sign
complies with all applicable local, county and state codes, and is of a design,
character and at a location reasonably satisfactory to Landlord. The signs shall
be provided and installed by Tenant as part of the Concession Fund and the signs
shall be removed and the Buildings restored to their original condition at
Tenant's expense at the end of the Term. So long as Tenant occupies more
Rentable Area in the Buildings than any other tenant, Landlord shall grant no
further signage rights to other tenants. At such time as (i) the rights of
Quality Systems, Inc. expire in and to the Centerpointe II Building, and (ii) in
the event Tenant is leasing at least twenty-five percent (25%) of the Rentable
Area of the Centerpointe II Building, and (iii) there is no contiguous space
leased to a single tenant or contiguous empty space in the Centerpointe II
Building containing a Rentable Area which is greater than the Rentable Area
leased by Tenant in the Centerpointe II Building, then Tenant shall have the
right to install one illuminated sign on the top of the Centerpointe II Building
identifying Tenant's corporate name or logo. Such sign shall be subject to the
same requirements as are set forth above with respect to the signs on the
Centerpointe I Building.

         56.       Storage Space.

         Tenant shall have the right, at its sole cost and expense, to convert
up to approximately 3,000 square feet of Tenant's garage parking area (described
in Article 60 below) to a storage area provided that such conversion is in
accordance with law and is in a location and design acceptable to Landlord,
which approval shall not be unreasonably withheld, delayed or conditioned. Any

                                       49
<PAGE>

parking converted to storage shall directly reduce Tenant's parking allocation,
as described in Article 60. All storage improvements shall be removed and the
garage restored to its original condition at Tenant's expense, at the end of the
Term.

         57.       Food Service In Centerpointe II Building. Landlord agrees
that so long as Tenant does not operate its own cafeteria in either of the
Buildings, Landlord shall not lease the portion of the first floor of the
Centerpointe II Building which is presently leased to Centerpointe Cafe for use
other than as a deli-type food service operation comparable to that offered by
Centerpointe Cafe. Tenant acknowledges that Landlord shall have the right to
change the location of the food service operation to any other portion of the
first floor of the Centerpointe II Building (provided that such new space shall
provide for seating for at least 85 patrons), in which event the negative
covenant described in the first sentence of this Article shall apply only to
such space and that Landlord is free to change the identity of the tenant of
such food service operation from time to time during the Term of this Lease.

         58.       Non-Disturbance. As to each Overlessor, deed of trust
trustee, mortgagee or holder of any other interest to which this Lease shall
hereafter become subordinate pursuant to Article 35 or Article 36 (each a
"Senior Holder"), such subordination is subject to the express condition that so
long as Tenant is not in default in its obligations hereunder beyond applicable
grace periods, (a) Tenant will not be made a party in any action or proceeding
by such Senior Holder to recover possession of the Property and/or the Premises,
or to any trustee's or sheriff's sale of the Property or to foreclose any
mortgage, (b) Tenant's possession shall not be disturbed by such Senior Holder,
and (c) this Lease shall not be cancelled or terminated by such Senior Holder
and shall continue in full force and effect upon such foreclosure or recovery of
possession as a direct lease between Tenant and the person or entity acquiring
the interest of Landlord, or between Tenant and the Overlessor, as the case may
be, upon all the terms, covenants, conditions and agreements set forth in this
Lease, provided in each case that, unless the Senior Holder is the General
Electric Pension Trust, the trustees or any subsidiary thereof, neither such
Senior Holder nor any person or entity acquiring title to the Buildings as a
result of foreclosure or trustee's sale nor any successor or assign of either of
the foregoing shall be (i) bound by or liable for any payment of Rent which may
have been made more than thirty (30) days before the due date of such
installment, (ii) subject to any defense or offset which Tenant may have to the
payment of Rent or other performance under this Lease, unless a Senior Holder
that institutes a foreclosure or other conveyance of title to a Building or
Buildings has been notified of Tenant's claim of a set off right, and, if the
set off rights are determined pursuant to a court action or arbitration, has
been given the opportunity to appear in, an action in which Tenant is awarded a
set off right pursuant to Article 53.2 above, in which event Tenant's right of
set off shall be limited as against such Senior Holder or any party acquiring
such title to 75% of any Monthly Installments of Additional Rent payable
thereunder from time to time from and after the date on which such Senior Holder
or other party acquires title to a Building or Buildings, (iii) bound by any
amendment or modification to this Lease made without the consent of such Senior
Holder, (iv) liable for any monies owing by Landlord or on deposit with Landlord
to the credit of Tenant, which such Senior Holder shall not have received,
except as aforesaid, or (v) bound by or liable for any act or omission of any
prior Landlord, and Tenant shall not have any right to set off (except as
provided in clause (ii) above) or assert against such Senior Holder or other
person or entity any claim or damages arising therefrom. The provisions of this

                                       50
<PAGE>

Article 58 shall be self-operative and no further instrument of subordination or
attornment shall be required to be provided by any Senior Holder or by Tenant.
Tenant agrees, however, whenever requested to do so upon reasonable notice, to
execute such instruments confirmatory of the provisions of this Article 58 as
Landlord or any Senior Holder requesting the same may reasonably require.

         59.       Exercise Room. Landlord shall provide an allowance of $35,000
for Tenant's purchase of exercise equipment for use in the fitness center which
Tenant intends to construct in the Centerpointe I Building. The foregoing
equipment allowance shall be in addition to the Concession Fund. The fitness
center shall otherwise be constructed by Tenant at Tenant's sole cost and
expense.

         60.       Parking. Tenant shall have the right to park up to 3.6
automobiles per 1,000 rentable square feet of the Premises free of charge to
Tenant throughout the Term (including any renewal terms), subject to
readjustment pursuant to Article 56 above. Tenant's total parking allotment
shall initially be eight hundred seventy-one (871) spaces (which spaces shall be
unassigned for the portion of the garage beneath the Centerpointe II Building),
comprised of seven hundred fourteen (714) spaces in the garage and one hundred
fifty-seven (157) spaces on the surface lot. Landlord shall designate within the
garage that portion of the garage for use by tenants of each of the respective
Buildings. Tenant's garage parking shall include the entire portion of the
garage designated by Landlord for the use of the Centerpointe I Building (which
portion shall be below the Centerpointe I Building) provided that Tenant's usage
shall not restrict access and use of the parking areas for the Centerpointe II
Building.

         61.       Right of First Offer.

                   61.1.    At any time that there remains at least four (4)
years in the Term, including during any exercised Renewal Periods, (provided,
however, that the rights set forth in this Article 61 during a Renewal Period
shall only be applicable if Tenant is occupying eighty percent (80%) or more of
the Rentable Area of the Centerpointe I Building), and provided Tenant is not in
default of any of the terms and conditions in this Lease, Tenant shall have the
rights of first offer set forth in this Article with respect to any space in the
Centerpointe II Building that becomes available following (or in anticipation
of) the vacation of such space by any tenant, provided that the space is not as
of the date of this Lease under any previous options or rights of first offer or
first negotiations to any other tenant (or its assignee or sublessee) of the
Centerpointe II Building (the "First Offer Space"). First Offer Space shall not
include any space which was not previously leased to and occupied by another
tenant. Gin the event that Landlord shall propose to actively market or lease
any First Offer Space to prospective tenants' then Landlord shall first give
written notice (the "Offer Notice") to Tenant notifying Tenant of such intention
and designating the First Offer Space which Landlord intends to so market or
lease and specifying in good faith the Base Rent, Additional Rent, escalations,
tenant concessions and other terms and the date on which Landlord would require
Tenant or the prospective tenant to occupy such First offer Space (each such
date shall herein be defined as a "Scheduled Commencement Date") Upon the giving
of an Offer Notice by Landlord, Tenant shall thereupon have an option (a "Right
of First Offer"), exercisable by notice (an "Acceptance Notice") given to
Landlord not later than ten (10) business

                                       51
<PAGE>

days after the receipt of the Offer Notice, to lease the designated First Offer
Space on the terms and conditions specified below in this Article. If the First
Offer Space shall be for a term which is not coterminus with the Term of this
Lease, Landlord's Offer Notice shall also include the terms and conditions upon
which Landlord would lease the First Offer Space for a term that is coterminus
with the Term, and Tenant shall elect in its Acceptance Notice whether Tenant
shall lease the First Offer Space for a coterminus term upon such terms and
conditions or for the term that Landlord had otherwise been marketing for the
First Offer Space. In the event Tenant does not exercise its option as aforesaid
for any First Offer Space as to which Tenant receives an Offer Notice from
Landlord, then Landlord shall have the right to enter into a lease with respect
to such designated First Offer Space (on terms substantially similar to, and at
a net effective base rental which is no less than 95% of, the terms of the Offer
Notice) with another tenant during the period which is twelve (12) months after
the date of Landlord's Offer Notice. If Landlord enters into a lease with
another tenant for First Offer Space as aforesaid, at the end of the term of any
such lease, Tenant's rights of first offer shall be reinstated for the remainder
of the Term of this Lease as to such space, subject to the terms and conditions
herein stated.

                   61.2.    In the event that Tenant shall exercise its Right of
First offer with respect to any First Offer Space, all of the terms and
conditions of this Lease applicable to the Premises generally, shall apply to
such First Offer Space, except that Base Rent, Additional Rent, renewal options,
escalations, tenant concessions and other economic terms and any other terms set
forth in the Offer Notice shall control if inconsistent with this Lease (or if
not addressed in this Lease), and except as otherwise set forth below in this
Article. Landlord and Tenant shall execute a lease addendum within twenty (20)
days after the date of the Acceptance Notice to memorialize the terms of the
Offer Notice. First Offer Space shall be delivered to Tenant in its then "as-is"
condition and state or repair, unless otherwise specified in the Offer Notice.

                   61.3.    The Scheduled Commencement Date for First Offer
Space as to which Tenant shall have given an Acceptance Notice ("Accepted First
Offer Space") and the dates upon which Rent shall become due shall be specified
by Landlord in the Offer Notice. If Landlord shall fail to deliver timely
possession of such Accepted First Offer Space for any reason beyond Landlord's
control, Landlord shall not be subject to any liability to Tenant, provided,
however, that Landlord shall use reasonable efforts to evict any holdover tenant
and the date upon which Rent shall be payable shall be equitably adjusted.

                   61.4.    The Term of this Lease shall commence as to each
Accepted First Offer Space on such date, which for purposes of this Article
shall be a "Subsequent Lease Commencement Date" for such Accepted First Offer
Space, as shall be the date (the "Availability Date") Landlord makes such
Accepted First Offer Space available for the commencement of Tenant Work. On the
Subsequent Lease Commencement Date for such Accepted First Offer Space, such
First Offer Space shall become part of the Premises. This Lease shall terminate
as to Accepted First Offer Space upon the expiration of the Term, if the term
for such First Offer Space is co-terminus with the Term, or on the date
otherwise specified in the Offer Notice and elected by Tenant in the Acceptance
Notice.

                                       52
<PAGE>

                   61.5.    From and after the Subsequent Rent Commencement Date
for Accepted First Offer Space, the "Tenant's Centerpointe II Proportionate
Share" shall be increased by the percentage which is derived by dividing the
rentable square footage of such Accepted First offer Space by 203,630.

         62.       Expansion Space.

                   62.1.    So long as Tenant is not in default under the terms
of this Lease, Tenant shall have the option to lease the approximately 9,062
rentable square feet of the sixth (6th) floor and the approximately 9,469
rentable square feet of the tenth (10th) floor in the Centerpointe II Building
which are not presently leased to other tenants ("Expansion Space"), provided
that Tenant exercises its option to lease either or both partial floors by
written notice delivered to Landlord ("Expansion Notice") on or before March 31,
1993, which notice shall advise Landlord of the date that Tenant shall occupy
the Expansion Space, which date shall be no later than March 1, 1994. Landlord
shall make available the Expansion Space to Tenant for Tenant Work within five
(5) days after Landlord's receipt of the Expansion Notice.

                   62.2.    If Tenant delivers to Landlord its Expansion Notice
at any time on or before March 31, 1993, all of the terms and conditions of this
Lease applicable to the Premises shall apply to such Expansion Space, except as
set forth below in this Article. Expansion Space shall be delivered to Tenant in
its then "as-is" condition and state of repair, but the Concession Fund shall be
increased pro rata based on the square footage of the Expansion Space.

                   62.3.    The Term of this Lease shall commence as to such
Expansion Space on such date, which for purposes of this Lease shall be the
"Expansion Space Lease Commencement Date," as shall be the date Tenant or anyone
claiming under or through Tenant enters such Expansion Space to commence actual
construction of the Tenant Work.

                   62.4.    Tenant's obligation to pay Rent for the Expansion
Space shall commence on March 1, 1994 ("Expansion Space Rent Commencement
Date"). If Tenant occupies the Expansion Space for the Permitted Use prior to
the Expansion Space Rent Commencement Date, Tenant shall pay to Landlord for the
period between the date of such occupancy and the Expansion Space Rent
Commencement Date, an amount equal to Five Dollars ($5.00) per rentable square
foot per annum, in equal monthly installments, in advance, as Additional Rent
hereunder. All other obligations of Tenant pertaining to the Expansion Space
under this Lease shall commence on the Expansion Space Lease Commencement Date.

                   62.5.    Unless Tenant exercises its option to lease both of
the partial floors that comprise the Expansion Space, as provided in Article
62.1 above, Landlord agrees, (i) as to one of the two partial floors, to be
selected by Landlord, if neither partial floor is so leased by Tenant, or (ii)
as to the remaining partial floor, if one of the partial floors is so leased by
Tenant (the applicable floor in item (i) or (ii) above is herein defined as
"Five Year Space"), that Landlord will not enter into any lease for the Five
Year Space for a term that exceeds five (5) years, and following the expiration
of the term of such lease for the Five Year Space, Tenant shall have the option
to lease the Five Year Space, to be exercised by the delivery of a notice to
Landlord within thirty (30) days after Landlord provides Tenant with written
notice as to the availability of the Five

                                       53
<PAGE>

Year Space, provided that the Base Rent payable with respect to the Five Year
Space shall be at the "Market Rental Value," as defined in, and determined
under, Article 54.3 above. Any renewal rights granted to a tenant of the Five
Year Space shall be subordinate to Tenant's option as aforesaid.

                   62.6.    After the Expansion Space Rent Commencement Date
with respect to the Expansion Space, Tenant's Centerpointe II Proportionate
Share shall be increased by an amount equal to the percentage derived by
dividing the rentable square footage of the Expansion Space by 203,630.

         63.       Measurement of Premises.  Intentionally Omitted

         64.       Tenant's Affiliation Representation. Tenant represents and
warrants that (i) it does not directly or indirectly control the General
Electric Company and is not directly or indirectly controlled by or under common
control with the General Electric Company; (ii) neither the Tenant nor any
principal of the Tenant is an officer, director or employee of the General
Electric Company or any subsidiary of any affiliated company of the General
Electric Company; and (iii) it is not a partnership in which the General
Electric Company or any subsidiary of any affiliated company of the General
Electric Company is a ten percent (10%) or more (directly or indirectly, in
capital or profits) partner.

         65.       Arbitration

                            (a)      If any controversy shall arise between the
parties with respect to the matters stated in this Lease to be resolved by
arbitration and that dispute shall not be resolved by the parties within ten
(10) days after either of the parties shall notify the other of its desire to
arbitrate the dispute, then the dispute shall be settled by arbitration, as
hereinafter provided, and judgment upon the award shall be entered in any court
having jurisdiction. The arbitrators shall have no power to change any
provisions of this Lease in any respect, and the jurisdiction of the arbitrators
is expressly limited accordingly. Neither party shall interrupt the progress of
its respective area of performance under this Lease pending the determination in
the arbitration proceeding.

                            (b)      The party desiring such arbitration shall
give written notice to that effect to the other party and shall in such notice
appoint a disinterested person in the Northern Virginia area of recognized
competence and experience in the field which is the subject matter of the
dispute as one of the arbitrators. Within fifteen (15) days thereafter, the
other party shall, by written notice to the original party, appoint a second
disinterested person in the Northern Virginia area of recognized competence and
having at least ten (10) years experience in such field as an arbitrator. The
arbitrators thus appointed shall appoint a third disinterested person in the
Northern Virginia area of recognized competence in such field, and such three
arbitrators shall, as promptly as possible, determine such matter, provided,
however, that (i) if the second arbitrator shall not have been appointed as
aforesaid, the first arbitrator shall proceed on ten (10) days notice to the
parties to determine such matter; and (ii) if the two arbitrators appointed by
the parties shall be unable to agree, within fifteen (15) days after the
appointment of the second arbitrator, upon the appoint of a third arbitrator,
they shall give written notice of such failure to agree to the parties,

                                       54
<PAGE>

and, if the parties fail to agree upon the selection of such third arbitrator
within fifteen (15) days after the arbitrators appointed by the parties give
notice as aforesaid, then within ten (10) days thereafter either of the parties
upon written notice to the other party hereto may request such appointment by
the American Arbitration Association (or any organization successor thereto), or
in its absence, refusal, failure or inability to act, may apply for such
appointment to a Court of competent jurisdiction.

                            (c)      The arbitration shall be conducted in
accordance with the rules of the American Arbitration Association (or its
successor) and the decision of a majority of the arbitrators (or sole
arbitrator, as the case may be) shall be binding, final and conclusive on the
parties and judgment thereon may be entered in any court having jurisdiction
thereof. Landlord and Tenant shall be entitled to present evidence and arguments
to the arbitrators. If a majority of the arbitrators (or sole arbitrator, as the
case may be) believe that expert advice would materially assist them in the
resolution of the matter in dispute, they may retain one or more qualified
persons, including, but not limited to, legal counsel, architects or engineers,
to provide such expert advice. The fees of the arbitrators and the expenses
incident to the proceedings shall be borne equally between Landlord and Tenant.
The fees of respective counsel engaged by the parties, and the fees of expert
witnesses and other witnesses called by the parties, shall be paid by the party
which loses in the proceedings The arbitrators shall give written notice to the
parties stating their determination, and shall furnish a copy of such
determination signed by them to each party.

         IN WITNESS WHEREOF, and intending to be legally bound hereby, the
parties hereto have executed this Agreement of Lease on the date first set forth
herein.

                                          Landlord:
                                          JOSHUA REALTY CORPORATION, a Delaware
                                          corporation

                                          By:      /s/ Steven D. Burton
                                                   ------------------------
                                          Steven D. Burton,
                                          Vice President

                                          Tenant:
                                          AMERICAN MANAGEMENT SYSTEMS, INC,
                                          a Delaware corporation

                                          By:      /s/ Frank A. Nicolai   (Seal)
                                                   -----------------------

[THE FOLLOWING PAGES OF THE ORIGINAL DOCUMENT INCLUDED AS EXHIBITS A-1 AND A-2
FLOOR PLANS OF THE PREMISES.]

                                       55

<PAGE>
                                 EXHIBIT "B"

                   Landlord's Base Building Modifications

         The following items are to be the sole responsibility of the Landlord.
The items will be completed in accordance with the dates indicated below:

         1.      Landlord will provide electrical sub-meters for first floor
tenant space in the Centerpointe I Building by December 1, 1992 and the third
and the fourth floors in the Centerpointe II Building by August 1, 1993.

         2.      The base Building core shells were constructed in accordance
with 1984 BOCA Codes at which time the building met all applicable codes.
Landlord will make any modifications allowable per code to bring the Building
up to the 1990 BOCA Code by December 1, 1992.

         3.      Landlord will provide roll-down doors at garage entry/exits
with card readers for security purposes by December 1, 1992.

         4.      By December 1, 1992, Landlord will provide an awning over the
loading dock area from the exterior Building doors to compactor area for the
Centerpointe I Building.  Additionally, by December 1, 1992 a ramp will be
constructed in place of the stairs adjacent to the dock for the Centerpointe I
Building.  The final design, material, color and location shall be subject to
all County codes, as well as Tenant's review.

         5.      Landlord will reimburse Tenant for the costs incurred in
connection with the removal of all existing data/telecommunications wiring from
previous tenants.  Such reimbursement shall be in addition to the Concession
Fund.

         6.      Landlord will diligently pursue alternatives to provide easier
walking access to Fair Oaks Mall.  Landlord's total cost for design,
engineering and construction shall not exceed $25,000.  Any in-house costs
associated with the approval process shall be at the Landlord's expense.

         7.      Landlord has negotiated with the County for the right of
Tenant to occupy, on a rent-free basis, a maximum of 2,000 square feet in the
Centerpointe I Building in a location reasonably acceptable to the County, for
use as a construction management office.  Tenant agrees to indemnify, defend
and hold Landlord harmless from and against any loss arising from Tenant's use
of such space.

         8.      Landlord will provide Tenant with transformers to accommodate
4 watts per square foot demand load at 120 volts for tenant power on a floor by
floor basis on the respective Lease Commencement Date and Subsequent Lease
Commencement Date for each floor.

                                     B-1
<PAGE>
         9.      Based on a maximum occupancy of one hundred ten (110) people
on a typical full office floor, the Landlord will provide 2,200 cubic feet per
minute (CFM) of outside air per floor.  The actual available outside air
volume, per floor, will be confirmed by an AABC or NEBB certified air balance
report.  All costs associated with providing certified air balance report shall
be borne by Landlord.  Should the actual available outside air volume on a
typical office floor be less than 1,980 CFM of outside air, the Landlord, at
its expense, will increase outside air volume to a minimum 2,200 CFM, per
floor, by May 1, 1993.

         10.     Landlord will provide the necessary improvements to reduce the
average noise levels in office areas not to exceed NC-35 and areas within 101
of machine rooms not to exceed NC-40.  Tenant will assist Landlord by
attempting to locate non-office uses around mechanical rooms on the respective
Lease Commencement Date and Subsequent Lease Commencement Date for each floor.

         11.     Landlord shall prepare a plan with respect to ADA requirements
for the Buildings by December 15, 1992, which Tenant shall have the right to
review (but not approve), it being acknowledged that Landlord shall in its sole
judgment determine what modifications to the Core Elements may be necessary to
comply with ADA.

                                      B-2
<PAGE>
                                  EXHIBIT "C"

                     Tenant Design and Construction Process

         Tenant shall construct the Tenant Work in a good and workmanlike
manner and in compliance with all laws and all requirements of insurance
underwriters rating or insuring the Buildings, the Premises and/or the
Property, and in accordance with the following requirements:

         1.      DESIGN.

                 A.       The plans, specifications and drawings for the Tenant
Work (the "Tenant Plans") shall be prepared by Tenant's architect and
engineers, who shall be licensed and registered in the Commonwealth of
Virginia, shall be sufficient for governmental approval and construction
thereof, and comply with the plans and specifications for the Buildings and
with all applicable laws, ordinances, rules, regulations and other requirements
of all governmental and quasi-governmental authorities having jurisdiction
thereof and all insurance requirements.

                 B.       The Tenant Plans for the Initial Space shall be
delivered to Landlord promptly following the date hereof for Landlord's
approval, and, for Subsequent Space, no later than the same time such Plans are
submitted to Tenant's General Contractor (as defined in Paragraph 2 below) for
pricing of Tenant Work on such Subsequent Space.  Landlord shall not
unreasonably withhold, condition or delay its approval of the Tenant Plans or
any revisions thereto (the Tenant Plans as approved by Landlord are hereinafter
referred to as the "Final Plans") and within five (5) business days of receipt
of the Tenant Plans, Landlord will notify Tenant in writing ("Landlord's Plan
Notice") whether the Tenant Plans have been approved or disapproved, and if
disapproved, Landlord's Plan Notice shall explain in reasonable detail the
deficiencies that resulted in the disapproval.  Following receipt of Landlord's
Plan Notice, Tenant shall submit to Landlord revisions of the Tenant Plans
which correct the deficiencies.  If Landlord shall disapprove the revisions of
the Tenant Plans, Landlord's Revised Plan Notice shall explain in reasonable
detail the deficiencies which resulted in the disapproval.  Following receipt
of Landlord's Revised Plan Notice, Tenant shall submit to Landlord further
revisions to the Tenant Plans which correct the deficiencies.  The procedures
and time periods relating to submitting and resubmitting and approving or
disapproving revisions to the Tenant Plans shall apply to any subsequent
revisions to the Tenant Plans.

                 C.       Tenant shall have the right to make changes from time
to time to the Final Plans (herein called the "Revisions").  All Revisions
which affect structural, or materially affect electrical, plumbing or
mechanical components of the Buildings shall be subject to Landlord's prior
written approval, which approval shall not be unreasonably withheld,
conditioned or delayed.  No approval of Tenant Plans and/or Final Plans shall
in any way be deemed to be an agreement by Landlord that the Tenant Plans, the
Final Plans and/or the Tenant Work comply with any laws, ordinances, rules,
regulations or requirements of any governmental authority having jurisdiction
thereof or any insurance requirements.

                                      C-1
<PAGE>
         2.      COSTS.

                 Tenant shall enter into a construction contract ("General
Contract Agreement") for the performance of the Tenant Work with Davis
Construction Company (such firm being hereinafter referred to as the "General
Contractor").  Tenant shall have the right to change the General Contractor
subject to Landlord's prior written consent, which consent shall not be
unreasonably withheld, conditioned or delayed.  Landlord shall have the right
to review the mechanical, electrical and plumbing subcontractors that will
perform any of the Tenant Work, as well as any subcontractors that will perform
any structural work.  Prior to entering into the General Contract Agreement,
Tenant shall submit the same to Landlord for its approval, which approval shall
not be unreasonably withheld, conditioned or delayed.  The General Contractor
Agreement shall not be modified, amended or terminated without obtaining the
prior written consent of Landlord, which consent shall not be unreasonably
withheld, conditioned or delayed.  The General Contract Agreement and each
subcontract shall provide for a ten percent (10%) retainage until the Tenant
Work shall be substantially completed in accordance with the Final Plans.
Provided that Landlord disburses the Concession Fund in accordance with the
terms of Exhibit "D", Tenant shall pay, when due, all amounts owing to the
General Contractor or any other person in connection with the construction
and/or performance of the Tenant Work.  Tenant and the General Contractor shall
be solely responsible for the transportation, safekeeping and storage of
materials and equipment used in the performance of the Tenant Work, for the
removal of waste and debris resulting therefrom to the Buildings' dumpsters and
for any proven damage caused by them during the course of the Tenant Work to
the Buildings or the Property.  Tenant shall not permit any financing
statements or statements to be filed with respect to any of the foregoing
alterations, additions or improvements by Tenant.

         3.      COMPLETION.

                 A.       Tenant shall be solely responsible for the
construction of the Tenant Work.  Tenant and its contractors shall work in
harmony and shall not interfere with Landlord, Landlord's contractors, any
other tenants of the Buildings or such tenants' contractors.

                 B.       All Tenant Work shall be done in accordance with, and
subject to all of the terms and conditions provided in this Exhibit "C".  In
connection therewith, Tenant and/or its contractors shall provide to Landlord,
and shall maintain at all times during the performance of Tenant Work,
Insurance as described in the Insurance Addendum attached hereto as Schedule
"C-1".  Certificates for such insurance shall be furnished to Landlord before
Tenant or its contractors commence to perform Tenant's Work.  Landlord shall
not be liable in any way for any injury, loss or damage that may occur to any
of Tenant's, or Tenant's contractor's decorations, fixtures, installations,
supplies, materials, or equipment unless any such injury, loss or change is due
to Landlord's gross negligence or willful misconduct and is not covered by
insurance which Tenant  is required to carry pursuant to this Exhibit "C"; any
such entry upon the Premises by Tenant and/or its contractors being at their
sole risk.

                 C.       Prior to the final payment under the General Contract
Agreement for the Initial Space, or any segment of the Subsequent Space, Tenant
shall deliver to Landlord a copy of

                                      C-2
<PAGE>
the final certificate of occupancy (or a non-residential use permit, if such a
permit is issued in lieu of a certificate of occupancy) for the Initial Space
or the relative segment of the Subsequent Space, together with certificates of
substantial completion by Tenant's architect, Tenant's engineers and by the
General Contractor, all of which shall certify to Landlord that the Tenant Work
has been completed substantially in accordance with the Final Plans and any
changes thereto made in accordance with the terms of this Lease.  Prior to the
final payment under the General Contract Agreement, Tenant shall deliver to
Landlord a reproducible sepia of the "as built" plans and specifications for
the fully completed Tenant Work prepared and certified by Tenant's architect or
the General Contractor.  Without limiting the foregoing, Tenant shall be
responsible for obtaining a certificate of occupancy (or a non-residential use
permit, if such a permit is issued in lieu of a certificate of occupancy) for
the Premises or such other certificate or approval as shall be required in
order for Tenant to legally occupy the Premises and shall promptly deliver a
copy thereof to Landlord.

         4.      TENANT'S REPRESENTATIVES.

                 Tenant hereby constitutes and appoints Dale Moser, Tom Huba
and Mike Mitchell (AMS) and Mike Solomon and Gary Helminski (Cushman &
Wakefield) its representatives (individually a "Tenant Representative" and
collectively the "Tenant Representatives") to deal with Landlord in connection
with the Tenant Work.  Any notices and/or approvals given to or by any one of
the said Representatives shall be binding upon Tenant and Landlord shall be
entitled to rely on notices or approvals delivered by any one of such
Representatives.  Tenant may change the designation of the Tenant
Representatives by notice in writing to Landlord.

         5.      DISBURSEMENT PROVISIONS.

                 Tenant shall, from time to time during the course of
construction of the Tenant Work and following the completion of the
construction by Tenant of the Tenant Work, but not more frequently than once
per month, submit to Landlord an Application for Payment in the form attached
hereto as Exhibit "D" which shall set forth the amount of all costs and
expenses which have been incurred by Tenant to the date of such statement for
Tenant Work (excluding amounts previously reimbursed to Tenant by Landlord
pursuant to previous statements) and for which Tenant is entitled to
reimbursement from the Concession Fund as more particularly set forth in
Article 4.2 of the Lease to which this Exhibit "C" is attached.  Each
Application for Payment shall be accompanied by supporting waivers of liens
from the General Contractor and from each subcontractor to which payments will
be made from advances made pursuant to the Application for Payment.  Provided
that the Concession Fund has not been exhausted and there is no default (which
default shall not require the delivery of any notice or the expiration of any
cure periods for the purpose of relieving Landlord from any obligation to
advance any portion of the Concession Fund in the face of such default,
although Tenant shall otherwise be entitled to applicable notice and cure
periods as a condition precedent to Landlord exercising its remedies under the
Lease) under the Lease, Landlord will cause the approved amount to be paid to
Tenant on the fifth (5th) business day after Landlord's receipt thereof;
provided further that all other conditions set forth in this Exhibit "C" shall
have been satisfied.

                                      C-3
<PAGE>
         6.      TENANT SUBMISSIONS.

                 A.       Prior to the commencement of construction in the
Initial Space, and prior to the commencement of construction in any segment of
the Subsequent Space, Tenant shall submit to Landlord a copy of the building
permit or permits required for the construction of the Tenant Work as to such
space.

                 B.       Prior to the final payment under the General Contract
Agreement, Tenant shall deliver to Landlord final lien waivers from the General
Contractor, Tenant's architect and engineers (to the extent they are entitled
to file mechanic's liens with respect to their services) and all
subcontractors, materialmen and suppliers.  Tenant shall use its best efforts
to secure lien waivers as aforesaid.  If Tenant cannot secure any such lien
waiver(s) Tenant agrees to post a bond to clear any such lien if filed of
record.

         7.      OWNERSHIP OF IMPROVEMENTS.

                 Landlord and Tenant hereby agree and acknowledge that,
notwithstanding the fact that Tenant may be contracting for the design and
construction of the Tenant Work, immediately upon its installation in the
Premises, all Tenant Work (including, without limitation, all general office
construction items, all mechanical, plumbing and HVAC equipment, all voice or
data communications wiring, and all raised computer access flooring) shall be
and remain the property of Landlord, and shall not thereafter (except as
otherwise provided in the Lease) be subject to removal by Tenant or in any
other manner be deemed the property of Tenant.

         8.      TENANT'S RIGHTS.

                 In its performance of the Tenant Work, Tenant shall have the
right to take such actions and utilize such facilities as are customarily and
reasonably taken and utilized in the construction of comparable space, subject
to such customary and reasonable restrictions as Landlord may adopt in the
prudent management of the Buildings.  Tenant shall not be charged for the use
of utilities, elevators, loading docks, and similar Building facilities in the
construction of the Tenant Work.  No fees of any manner shall be charged by
Landlord for its review of plans and drawings or any supervision or inspection
of the Tenant Work.  Landlord shall cause any of its contractors working in the
Buildings to work in harmony with Tenant and the General Contractor, and
Landlord shall not knowingly permit any other contractors to interfere with the
performance of the Tenant Work.

                                      C-4
<PAGE>
Insurance Addendum
Page 1

                                 EXHIBIT "C-1"
                               INSURANCE ADDENDUM

This Insurance Addendum is a part of the Agreement between Owner and Contractor
dated ____ July 1992.

Notwithstanding anything to the contrary in the Agreement to which this
Addendum is attached, or in any other agreement between Contractor, Owner
and/or Architect, Landlord or their respective subcontractors, agents,
employees or representatives, the parties hereto agree as follows:

         All general liability and umbrella liability insurance coverage
         required herein or in any other agreement between the parties shall be
         written on an "Occurrence Basis".

         Contractor shall at all times during the period in which this Contract
         is in force, provide, maintain and require all subcontractors to
         provide and maintain the following types of insurance protecting the
         interest of Landlord and Owner and Contractor with limits not less
         than those as set forth below:

                 WORKER'S COMPENSATION INSURANCE (WC) to cover statutory limits
                 of the Worker's Compensation Law of the State of Virginia,
                 with Coverage B Employer's Liability coverage in limits not
                 less than $500,000

                 COMMERCIAL GENERAL LIABILITY (GGL) insurance for hazards of
                 (i) Premises Operations, (ii) Elevators and Escalators, (iii)
                 Independent Contractors, (iv) Coverage for explosion,
                 collapse, and underground (X, C, U), (v) Products and
                 Completed Operations coverage, (vi) Contractual Liability on a
                 "Blanket" basis designating all written and oral contracts
                 related to the work, (vii) Personal Injury Liability for
                 groups of offenses A, B, and C (with exclusions pertaining to
                 liability assumed by the insured under contract, and to
                 personal injury sustained by any person as a result of an
                 offense directly or indirectly related to the employment of
                 each person by the named insured deleted), and (viii)
                 Incidental Medical Malpractice coverage.  Such Commercial
                 General Liability Insurance must be endorsed with a Broad Form
                 Property Damage Endorsement (including Complete Operations).

                 The Contractual Liability coverage must be endorsed so that
                 all exclusions relating to explosion, collapse and underground
                 hazards are deleted.  The CGL insurance shall have primary
                 coverage limits not less than following:

<PAGE>
Insurance Addendum
Page 2

                 BODILY INJURY LIABILITY/PROPERTY DAMAGE LIABILITY - $1,000,000
                 each occurrence, combined single limit.

                 PERSONAL INJURY LIABILITY - $1,000,000 each person;

AUTOMOBILE LIABILITY INSURANCE (Auto) covering all owned, leased, non-owned and
hired automobiles used in connection with the Work with coverage limits not
less than the following:

                 BODILY INJURY LIABILITY/PROPERTY DAMAGE LIABILITY - $1,000,000
                 each person and each occurrence, combined single limit.

COMPREHENSIVE CATASTROPHE LIABILITY INSURANCE (Umbrella) indemnifying for
ultimate net loss sustained by reason of any liability whether imposed by law,
assumed under contract, or otherwise incurred arising out of:

                 BODILY INJURY, including personal injury, because of bodily
                 injury, including death at any time resulting therefrom,
                 sustained by any person or persons.

                 PROPERTY DAMAGE, for losses due to damages to or destruction
                 of tangible property, including loss of use of such property
                 resulting therefrom.

         The Umbrella insurance shall set forth coverage limits with respect to
         each occurrence, except for the products hazard coverage which shall
         contain aggregate limits for each annual period.  With regard to
         Contractor, the Umbrella insurance shall have coverage limits not less
         than FIVE MILLION DOLLARS AND 00/100 ($5,000,000) for each occurrence
         and in the aggregate as applicable in excess of the amount set forth
         in subparagraphs (WC), (CGL) & (AUTO) above.  For each subcontractor
         employed in conjunction with the Work, the Umbrella insurance shall
         have coverage limits not less than TWO MILLION DOLLARS AND 00/100
         ($2,000,000) for each occurrence and in the aggregate as applicable in
         excess of the amount set forth in subparagraphs (WC), (CGL) & (AUTO)
         above.

         In the event that Contractor or  any subcontractors have or obtain
         insurance coverage in amounts in excess of those listed above, such
         additional insurance coverage shall also insure to the benefit of the
         Landlord and Owner.

Contractor shall be liable to Landlord and Owner for the actions of Contractor,
its subcontractors and their respective agents, servants and employees for any
losses suffered by Landlord and Owner which would otherwise have been covered
by any insurance required hereunder in the event Contractor fails to obtain any
such addendum.  (Any subcontractor working directly for Owner shall be deemed a
General Contractor for purposes of this addendum and shall comply with all
obligations herein required of Contractor).

<PAGE>
Insurance Addendum
Page 3

Before commencing the Work, Contractor and all subcontractors shall furnish
certificates of insurance satisfactory to Landlord and Owner from each
insurance carrier indicating that the above-required insurance is in force, the
amount of the carrier's liability thereunder, and further providing that the
insurance will not be canceled, changed or non-renewed until the expiration of
at least thirty (30) days after written notice of such cancellation or change
has been mailed to and received by Landlord and Owner.  Contractor shall
deliver copies of all policies from Contractor and Subcontractors if requested
by Landlord and Owner.

All insurance described herein shall be written in a company or companies
satisfactory to Landlord and Owner.  If Contractor or any subcontractor fails
to procure and maintain the above-described insurance, or any portion thereof,
Landlord and Owner shall have the right, but not the obligation to procure and
maintain the required insurance for and in the name of such party and such
party shall pay the cost thereof and shall furnish all information necessary to
acquire and maintain such insurance.  Neither Contractor nor subcontractors
shall violate or knowingly permit any violation of any condition or terms of
the policies of insurance described herein.  All CGL, Auto and Umbrella
Policies shall designate Landlord and Owner as additional insured with
Certificates of Insurance provided as evidence.  Any other insurance maintained
by Landlord and, Owner shall be in excess of all contractors and all tiers of
subcontractor's insurance required herein and shall not contribute with it.

CONTRACTOR(S) shall require all policies of insurance that are in any way
related to the work and that are secured and maintained by Contractor and all
tiers of subcontractors to included clauses providing that each underwriter
shall waive all of its rights of recovery, under subrogation or otherwise
against Landlord and Owner, and shall be so designated on said certificate.

CONTRACTOR SHALL MAINTAIN ALL BUILDER'S RISK INSURANCE COVERAGE FOR DESIGNATED
WORK IN THE AMOUNT OF THE CONTRACT, AND SHALL NAME THE LANDLORD AND OWNER AS
ADDITIONAL NAMED INSURED. ANY DEDUCTIBLE ENCOUNTERED IN THE SUBMISSION OF A
CLAIM SHALL BE BORNE SOLELY BY THE CONTRACTOR.

Landlord and Owner shall not be responsible for obtaining or maintaining in
force insurance on construction equipment, tools or personal effects, owned by
or rented to or in the care, custody and control of Contractor or any
subcontractors, nor shall Landlord and Owner be responsible for such equipment,
tools or personal effects.

All insurance required hereunder shall be maintained continuously until final
completion as certified by Architect and until accepted or approved by Landlord
and Owner.  All insurance shall provide for Owner to take occupancy of the Work
or any part thereof during the term of said insurance.

All policies issued shall specify as additional insured LPC Commercial
Services, Inc., Joshua Realty Corporation and American Management Systems, Inc.

<PAGE>
                                  EXHIBIT "D"

                          Concession Fund Voucher Form

         _______________, as Tenant Representative for American Management
Systems, Inc. ("Tenant") hereby certifies to Joshua Realty Corporation
("Landlord") as follows:

         1.      The sum of $__________________ (the "Draw Request") is
requested for disbursement from the Concession Fund and such sum has been
properly expended for items permitted under Article 4.2 of the Lease.  Attached
hereto as Schedule "D-1" is a list of the items for which payment is hereby
requested and the portion of the Draw Request attributable to each such item.

         2.      That the Tenant Work for which the Draw Request is being made
has been performed in accordance with Exhibit "C" to the Lease.

         3.      Attached hereto as Schedule "D-2" are the lien waivers from
all contractors that will be paid by Tenant, or the General Contractor, from
the Draw Request.

         4.      Attached hereto as Schedule "D-3" is the General Contractor's
certification that the Tenant Work for which application for payment is being
made has been completed.

                                  ----------------------------------
                                  Tenant Representative for American
                                  Management Systems, Inc.

                                      D-1
<PAGE>

                                  EXHIBIT "E"

                     CLEANING, MAINTENANCE, SPECIFICATIONS,
                             STAFFING AND FREQUENCY

SERVICES

ELEVATORS
(NIGHTLY SERVICES)

1.       Vacuum carpet in all passenger elevators nightly.  Spot clean carpet,
         as necessary.

2.       Carpet to be shampooed as necessary, but no less than once per month.

3.       Elevator carpets to be clean on a nightly basis.

4.       Clean lobby elevator saddles, doors and frames, nightly.  Polish with
         approved Polish, as required.

5.       Clean elevator frames and doors (both sides) of all fingerprints and
         smudges.

6.       Dust and remove all marks on ceiling and light fixtures in cab as
         necessary, but no less than once per week.

7.       Remove all unauthorized marks and writing from insides of elevator
         cabs nightly, using manufacturer's approved method.

8.       Clean all interior cab wall surfaces and wash as required, but no less
         than once per week.

9.       Report all mechanical deficiencies or damage to owners representatives
         on sight.

10.      Remove all gum and foreign matter on sight.

11.      Clean all elevator saddles as required, but no less than once per
         week.

12.      Elevator contractor to clean pits on a monthly basis; the only person
         allowed in the pit is the elevator contractor.

13.      Wet mop and remove all stains from freight elevator flooring.

GENERAL OFFICES
(INCLUDES ALL BASEMENT AREAS)
(NIGHTLY SERVICES)

1.       All flooring swept nightly.

                                      E-1
<PAGE>

2.       All carpeted areas and rugs carpet-swept nightly and vacuum-cleaned
         weekly.

3.       Wastepaper baskets, ashtrays, receptacles, etc. emptied and cleaned
         nightly and damp dusted when necessary, but no less than once per
         week.

4.       Cigarette urns, cleaned nightly and sand or water replaced when
         necessary, but no less than once per week.

5.       All furniture, fixture and window sills dusted and wiped cleaned
         nightly.

6.       All glass furniture tops cleaned nightly.

7.       All baseboards, chair rails and trim dusted weekly.

8.       All water fountains washed clean nightly.

9.       Slop sink rooms cleaned nightly.

10.      Fill toilet tissue and towel dispensers as required.

11.      Service sanitary napkin dispensers.  Sanitary napkins and products
         furnished by contractor.  Dispensers shall be maintained by
         contractor.

12.      Collect coins from sanitary napkin dispensers and turn proceeds over
         to duly authorized representative of contractors.

13.      Report all mechanical deficiencies, i.e. dripping faucets, burnt out
         lights, etc. to the Building Manager.

LAVATORIES (PUBLIC)

1.       All flooring swept and washed nightly.

2.       All mirrors, powder shelves, bright work, etc. including flushometers,
         piping and toilet seat hinges washed and polished nightly.

3.       All basins, bowls, urinals and toilet seats (both sides) washed
         nightly.

4.       All partitions, tile walls, dispensers and receptacles dusted nightly.

5.       Paper towels and sanitary disposal receptacles emptied and cleaned
         nightly.

6.       Paper towels, soap dispensers and toilet paper replenished daily or
         more frequently as required.

                                      E-2
<PAGE>

HIGH DUSTING - OFFICE AREAS

Do all high dusting approximately once a month, including, but not limited to,
the following:

1.       Dust all pictures, frames, charts, graphs and panel wall hangings not
         reached in nightly cleaning.

2.       Dust all vertical surfaces such as walls, partitions, ventilating
         louvers and other surfaces not reached in nightly cleaning.

3.       Dust all lighting fixtures (exterior only).

4.       Dust all venetian blinds and window frames approximately once every
         two months.

PERIODIC CLEANING - OFFICE AREA

1.       Wipe clean all interior metal as necessary, but no less than once per
         month.

2.       Dust all door louvers and other ventilating louvers within reach
         weekly.

3.       Remove finger marks from metal partition and other surfaces when
         necessary, but no less than once per week.

PERIODIC CLEANING - LAVATORIES (PUBLIC)

1.       Machine-scrub flooring when necessary, but no less than once per
         month.

2.       Wash all partitions, tile walls and enamel surfaces monthly with
         proper disinfectant when necessary, but no less than once per month.

3.       Dust exterior of lighting fixtures monthly.

4.       High dust monthly.

PUBLIC AREAS
(NIGHTLY SERVICES)

1.       All public stairwells to be swept and dusted weekly.

2.       All public stairwells to be washed as necessary, but no less than once
         per month.

3.       Maintain all bright metal.

                                      E-3

<PAGE>

BUILDING SERVICE AREAS
(NIGHTLY SERVICES)

1.       Keep locker rooms in neat and orderly condition at all times.  Wash
         lockers once per month.  Wash and wax floor weekly.

2.       Remove all gum and foreign matter from sidewalks on sight.

3.       Lay down and remove runners as necessary.

4.       Remove and clean all spillages.

5.       Wash walls in main floor freight lobby, as required, but no less than
         once per month.  Scrub floor nightly.

6.       Storerooms, electric and telephone closets are to be kept free from
         debris and material.  Floors are to be swept weekly.  Reports of any
         stored extraneous material or equipment are to be made to the Building
         Manager immediately.

7.       Slop sinks, locker areas, etc. to be thoroughly cleaned.

8.       Contractors equipment to be stored in a central location supplied by
         Landlord.

9.       Lights shall be extinguished as areas are cleaned.

10.      Contractor's employees to work behind closed doors at all times.  The
         cleaning supervisor shall inspect all spaces to insure compliance.

LOBBY
(NIGHTLY)

1.       Sweep and remove gum.

2.       Sweep travertine/marble floor nightly (Sunday through Friday).

3.       Remove all hand marks on doors, walls, stairwell doors, directories
         and urns.

4.       Dust all mullions, frames, and ledges with treated cloths.

5.       Wash travertine/marble walls quarterly.

6.       Damp wipe interior black wall surfaces floor to ceiling as required,
         but no less than once per week.

7.       Damp and dry wipe interior of all revolving door drums as required,
         but no less than once per week.

                                      E-4
<PAGE>

DAY PORTER SERVICES

Services to be provided by one (1) Day Porter under Building Manager's
direction and supervision.  Duties are as follows:

1.       Police sidewalks.

2.       Police main lobby as required, but no less than three times daily.

3.       Dust and clean out lobby grill work.

4.       Police public areas of multi-tenant floors twice daily.

5.       Damp wipe lobby directories.

6.       Keep entrance door glass clean.

7.       Police men's lavatories on multi-tenant floors as required, but no
         less than twice daily.

8.       Police and vacuum elevator cabs as required, but no less than twice
         daily.

9.       Dust tops of revolving door housing.

10.      Lay down and remove foul weather mats as necessary.

11.      Snow/Ice removal to avoid any accumulation.

12.      Police main lobby on a continual basis.

EXTERMINATION

1.       All services are to be performed by an approved operator licensed by
         Board of Health and certificate of such shall be on file with the
         Building Manager.

2.       Public spaces, slop sink, freight areas, Electric and Telephone
         closets, and mechanical spaces throughout the building shall be kept
         under pest control treatment at least once per month or as required.

3.       All emergency treatments to the above shall be at the expense of the
         contractor.

SECURITY

         The Contractor shall provide security from 5 PM to 8 PM Monday through
         Friday using porter security personnel.  The porter security person
         shall be available at all times to let people in and out.

                                      E-5

<PAGE>

         Friday midnight until Saturday midnight - Security Guard S Service.
         Contractor shall provide security services 52 weeks per year including
         all holidays.

                                      E-6
<PAGE>

                                  EXHIBIT "F"

                             RULES AND REGULATIONS

         1.      Tenant shall not obstruct or interfere with the rights of
other tenants of the Centerpointe II Building, or of persons having business in
the Centerpointe II Building, or in any way injure or annoy such tenants or
persons.  Tenant will not conduct any activity within the Premises which will
create excessive noise anywhere in the Buildings.

         2.      Canvassing, soliciting and peddling in the Buildings are
prohibited, and Tenant shall cooperate to prevent such activities.

         3.      Tenant shall not bring or keep within the Buildings any
animal, bicycle, motorcycle, or other type of vehicle except as required by
law.

         4.      All office equipment and any other device of any electrical or
mechanical nature shall be placed by Tenant in the Premises in settings
approved by Landlord, so as to absorb or prevent any vibration, noise or
annoyance.  Tenant shall not construct, maintain, use or operate within the
Premises or elsewhere in the Buildings or outside of the Buildings any
equipment or machinery which produces music, sound or noise, which is audible
beyond the Premises.  Tenant shall not cause improper noises, vibrations or
odors within the Buildings.

         5.      Tenant shall not deposit any trash, refuse, cigarettes or
other substances of any kind within or out of the Buildings except in the
refuse containers provided therefor.  No material shall be placed in the trash
boxes or receptacles if such material is of such nature that it may not be
disposed of in the ordinary and customary manner of removing and disposing of
office buildings' trash and garbage without being in violation of any law or
ordinance governing such disposal.  Tenant shall be charged the cost of removal
for any items left by Tenant that cannot be so removed.  All garbage and refuse
disposal shall be made only through entryways and elevators provided for such
purposes and at such times as Landlord shall designate.  Tenant shall not
introduce into the Buildings any substance which might add an undue burden to
the cleaning or maintenance of the Premises or the Buildings.  Tenant shall
exercise its best efforts to keep the sidewalks, entrances, passages, courts,
lobby areas, garages or parking areas, elevators, escalators, stairways,
vestibules, public corridors and halls in and about the Buildings (hereinafter
"Common Areas") clean and free from rubbish.  Tenant shall not cause any
unnecessary labor by reason of Tenant's carelessness or indifference in the
preservation of good order and cleanliness.

         6.      The Common Areas and roof of the Buildings are not for the use
of the general public, and Landlord shall in all cases retain the right to
control or prevent access thereto by all persons whose presence, in the
judgment of Landlord, shall be prejudicial to the safety, character, reputation
or interests of the Buildings and their tenants.  Except as otherwise provided
in the Lease, Tenant shall not enter or install equipment in the mechanical
rooms, air conditioning rooms, electrical closets, janitorial closets or
similar areas or go upon the roof of the Buildings

                                      F-1

<PAGE>

without the prior written consent of Landlord.  Except as otherwise provided in
the Lease, Tenant shall not install any radio or television antenna,
loudspeaker or other device on the roof or exterior walls of the Buildings.

         7.      Without limitation upon any of the provisions of the Lease,
Tenant shall not mark, paint, drill into, cut, string wires within, or in any
way deface any part of the Buildings, without the prior written consent of
Landlord, and as Landlord may direct.  Upon removal of any wall decorations or
installations or floor coverings by Tenant, any damage to the walls or floors
shall be repaired by Tenant at Tenant's sole cost and expense.  Tenant shall
not lay linoleum or similar floor coverings so that the same shall come into
direct contact with the floor of the Premises and, if linoleum or similar floor
covering is to be used, an interlining of builder's deadening felt shall be
first affixed to the floor, by a paste or other materials soluble in water.
The use of cement or other similar adhesive material is expressly prohibited.
Floor distribution boxes for electric and telephone wires must remain
accessible at all times.

         8.      Tenant shall not install or permit the installation of any
awnings, shades, mylar films or sunfilters on windows.  Tenant shall cooperate
with Landlord in obtaining maximum effectiveness of the cooling system of the
Buildings by closing drapes and other window coverings when the sun's rays fall
upon windows of the Premises.  Tenant shall not obstruct, alter or in any way
impair the efficient operation of Landlord's heating, ventilating, air
conditioning, electrical, fire, safety or lighting systems, nor shall Tenant
tamper with or change the setting of any thermostat or temperature control
valves in the Buildings.

         9.      Tenant shall not use the washrooms, restrooms and plumbing
fixtures of the Buildings, and appurtenances thereto, for any other purpose
than the purpose for which they were constructed, and Tenant shall not deposit
any sweepings, rubbish, rags or other improper substances therein.  Tenant
shall not waste water by interfering or tampering with the faucets or
otherwise.  If Tenant or Tenant's servants, employees, agents, contractors,
jobbers, licensees, invitees, guests or visitors cause any damage to such
washrooms, restrooms, plumbing fixtures or appurtenances, such damage shall be
repaired at Tenant's expense, and Landlord shall not be responsible therefor.

         10.     Subject to applicable fire or other safety regulations, all
doors opening onto Common Areas and all doors upon the perimeter of the
Premises shall be kept closed and, during non-business hours, locked, except
when in use for ingress or egress.

         11.     Employees of Landlord shall not receive or carry messages for
or to Tenant or any other person, nor contract with nor render free or paid
services to Tenant or Tenant's servants, employees, contractors, jobbers,
agents, invitees, licensees, guests or visitors.  In the event that any of
Landlord's employees perform any such services, such employees shall be deemed
to be the agents of Tenant regardless of whether or how payment is arranged for
such services.

         12.     Tenant shall, upon the termination of its tenancy, provide
Landlord with the combinations to all combination locks on safes, safe cabinets
and vaults and deliver to Landlord all keys to the Buildings, the Premises and
all interior doors, cabinets and other key-controlled mechanisms therein,
whether or not such keys were furnished to Tenant by Landlord.  In the

                                      F-2
<PAGE>

event of the loss of any key furnished to Tenant by Landlord, Tenant shall pay
to Landlord the cost of replacing the same or of changing the lock or locks
opened by such lost key if Landlord shall deem it necessary to make such a
change.  The word "key" as used herein shall refer to keys, keycards and all
such means of obtaining access through restricted access systems.

         13.     For purposes hereof, the terms "Landlord", "Tenant",
"Buildings" and "Premises" are defined as those terms are defined in the Lease
to which these Rules and Regulations are attached.  The term "Buildings" shall
include the Premises, and any obligations of Tenant hereunder with regard to
the Buildings shall apply with equal force to the Premises and to other parts
of the Buildings.

         14.     These Rules and Regulations are in addition to, and shall not
be construed to in any way modify or amend, in whole or in part, the
agreements, covenants, conditions and provisions of any lease of premises in
the Buildings.  The terms of the Lease shall supersede any provisions of these
Rules and Regulations which may be inconsistent with the terms of the Lease.

                                      F-3

<PAGE>

                                  EXHIBIT "G"

                          HVAC System Design Criteria

<TABLE>
<CAPTION>
SUMMER                                                WINTER

    <S>                            <C>                     <C>                           <C>
    Outside Temperature                                    Outside Temperature

            Dry Bulb               95 degrees F                    Dry Bulb               O degrees F
            Wet Bulb               78 degrees F

    Inside Temperature                                     Inside Temperature

            Dry Bulb               75 degrees F                    Dry Bulb               70 degrees F
            % Relative Humidity    50%                             % Relative Humidity    20%
</TABLE>

                                      G-1
<PAGE>

                                   EXHIBIT H

                       Legal Description of the Property

PARCEL A: BEGINNING at a point on the Southwesterly R/W line of Legato Road
(Route #656) said point being N 14 deg. 30' 12" W 72.49 feet from a point
marking the Northeasterly corner of the Fairfax Assembly of Good Church; thence
departing from the Road and running through the property of Faircenter Limited
Partnership the following courses: with a curve to the right whose radius is
26.00 feet (and whose chord is S 65 deg. 28' 14" W, 11.22 feet) an arc distance
of 11.31 feet; S 77 deg, 55' 48" W 200.47 feet; with a curve to the right whose
radius is 659.96 feet (and whose chord is S 86 deg. 10' 48" W, 189.40 feet) an
arc distance of 190.05 feet and N 08 deg. 21' 54" E 564.80 feet to a point on
the aforementioned Southwesterly R/W line of Legato Road; thence with the
Southwesterly line of Legato Road S 59 deg. 03' 43" E 129 feet and with a curve
to the right whose radius is 344.62 feet (and whose chord is S 56 deg. 04' 19"
E 35.95 feet) an arc distance of 35.97 feet to a point; thence departing from
the Road and running through the property of Faircenter Limited Partnership
with a curve to the left whose radius is 55.00 feet (and whose chord is S 48
deg. 51' 01" E 50.86 feet) an arc distance of 52.87 feet to a point on the
Southwesterly R/W line of Legato Road; thence with the Southwesterly R/W line
of Legato Road the following courses: with a curve to the right whose radius is
344.62 feet (and whose chord is S 40 deg. 30' 20" E 49.45 feet) an arc distance
of 49.49 feet; S 24 deg. 09' 12" E 84.71 feet; S 16 deg. 09' 12" E 147.80 feet;
S 11 deg. 30' 12" E 100.00 feet and S 14 deg. 30' 12" E 25.71 feet to the point
of beginning, containing 144,883 square feet of land, more or less.

                                      H-1
<PAGE>

                                   EXHIBIT H

BEGINNING at a point marking the intersection of the Southeasterly R/W line of
West Ox Road (Route #608) and the Southwesterly R/W line of Legato Road (Route
#656) ; thence with the Southwesterly R/W line of Legato Road S 59# 03' 43" E,
39.90 feet to a point; thence departing from the Road and running through the
property of Faircenter Limited Partnership S 08# 21' 54" W, 564.80 feet to a
point on the Northerly line of relocated Legato Road; thence with the said line
of relocated Legato Road the following courses: with a curve to the right whose
radius is 659.96 feet (and whose chord is N 78# 05' 37" W, 171.74 feet) and arc
distance of 172.22 feet; with a curve to the right whose radius is 420.00 feet
(and whose chord is N 62# 58' 47" W, 111.65 feet) an arc distance of 111.98
feet; with a curve to the right whose radius is 4500.00 feet (and whose chord
is N 55# 04' 04" W, 43.00 feet) an arc distance of 43.00 feet; N 47# 02' 47" W,
92.84 feet and with a curve to the right whose radius is 41.00 feet (and whose
chord is N 03# 10' 33" E, 63.02 feet) an arc distance of 71.88 feet to a point
on the aforementioned R/W line of West Ox Road; thence with the said R/W line
of West Ox Road N 53# 23' 54" E, 361.12 feet and with a curve to the left whose
radius is 582.96 feet (and whose chord is N 44# 35' 50" E, 178.39 feet) an arc
distance of 179.09 feet to the point of beginning, containing 140,326 square
feet of land.

                 TOGETHER WITH all rights appurtenant to the property described
above arising under a Declaration of Easements, Covenants and Related
Agreements, made by Faircenter Limited Partnership, a Delaware limited
partnership, dated as of February 2, 1989, and recorded February 15, 1989 in
the Clerk's Office of the Circuit Court of Fairfax County, Virginia in Deed
Book 7265, at page 1813.

                                      H-2
<PAGE>

                                  EXHIBIT "I"

                             INDEX OF DEFINED TERMS

<TABLE>
<CAPTION>
        TERM                                     ARTICLES IN WHICH DEFINED
- -------------------------                        -------------------------

<S>                                                  <C>
Acceptance Notice                                    61

Accepted First Offer Space                           61.3

ADA                                                  4.1

Additional Rent                                      7.1.4

Affiliate                                            50.1

Annual Base Rent                                     54.1

Annual Operating Costs                               7.4.1

Availability Date                                    61.4

Base Building Modifications                          Exhibit "B"

Base Rent                                            1.2,6

Base Year Assessment                                 7.1.1(e)

Base Year Real Estate Taxes                          1.3.2

Base Year Operating Expenses                         1.3.1,54.2

Buildings                                            1.1(c), 50.2

Centerpointe I Building                              1.1(a)

Centerpointe II Building                             1.1(b)

Centerpointe I Net Annual Operating Costs            7.4(a)

Centerpointe II Net Annual Operating Costs           7.4(b)

Centerpointe I Net Real Estate Taxes                 7.1.1(a)

Centerpointe II Net Real Estate Taxes                7.1.1(b)

Centerpointe I Premises                              1.1(a)
</TABLE>

                                      I-1

<PAGE>

<TABLE>
<CAPTION>
        TERM                                     ARTICLES IN WHICH DEFINED
- -------------------------                        -------------------------

<S>                                                  <C>
Centerpointe II Premises                             1.1(b)

Concession Fund                                      1.5, 4.2

Concession Fund Voucher Form                         4.2, Exhibit I'D"

Control Areas                                        52.1

County                                               4.3

Core Elements                                        4.1

Environmental Statutes                               52.1

Escalation Date                                      6.3

Escalation Period                                    6.3

Expansion Notice                                     62.1

Expansion Space                                      62.1

Expansion Space Lease Commencement Date              62.3

Expansion Space Rent Commencement Date               62.4

Extension Exercise Notice                            54.1

First Lease Year                                     3.3

First Offer Space                                    61

Five Year Space                                      62.5

Hard Costs                                           4.2

Hazardous Substances                                 52.4

Holdover Payment                                     4.3

Holidays                                             50.3

HVAC Off-Hours                                       9.1.1

HVAC Off-Hours Rate                                  50.4

Initial Space                                        1.4

</TABLE>

                                      I-2
<PAGE>

<TABLE>
<CAPTION>
        TERM                                     ARTICLES IN WHICH DEFINED
- -------------------------                        -------------------------

<S>                                                  <C>
Landlord                                             Introductory Paragraph
                                                     (page 1); 50.5

Landlord's Address                                   1.9(b)

Landlord's Control Area                              52.1

Last Lease Year                                      3.3

Late Charge                                          8

Lease Commencement Date                              3.1

Lease Interest Rate                                  50.6

Lease Taxes                                          7.1.2,50.7

Lease Year                                           3.3

Market Rental Value                                  54.3,54.3.2

Monthly Installment of Base Rent                     6.1.1

Mortgage                                             35.1

Negotiation Period                                   54.3

Net Annual Operating Costs                           7.4(c)

Net Real Estate Taxes                                7.1.1(c)

Occupancy Schedule                                   1.4

Offer Notice                                         61

Operating Expenses                                   54.2

Option Exercise Date                                 54.1

Ordinary Business Hours                              50.8

Overlessor                                           36

Permitted Use                                        1.8

Premises                                             1.1(c)
</TABLE>

                                      I-3

<PAGE>

<TABLE>
<CAPTION>
        TERM                                     ARTICLES IN WHICH DEFINED
- -------------------------                        -------------------------

<S>                                                  <C>
Prime Rate                                           50.9

Property                                             50.10

Proposed Recapture Space                             14.5

Proposed Transfer Date                               14.5

Real Estate Taxes                                    7.1.1,50.11

Recapture Notice                                     14.5

Renewal Period                                       54.1

Rent                                                 50.12

Rent Commencement Date                               3.2.1

Rentable Area of the Buildings                       50.13

Rentable Area of the Premises                        1.1(c), 50.14

Responsible Party                                    52.1

Right of First Offer                                 61

Scheduled Commencement Date                          61

Scheduled Rent Commencement Date                     1.4

Security Deposit                                     1.6

Senior Holder                                        58

Subsequent Escalation Date                           6.3

Subsequent Lease Commencement Date                   3.2,61.4

Subsequent  Rent Commencement Date                   3.2.2

Subsequent  Space                                    1.4

Substitute  Space                                    22.1

Substitute  Space Differential                       22.1

Substitute  Space Tenant                             22.1
</TABLE>

                                      I-4
<PAGE>

<TABLE>
<CAPTION>
        TERM                                     ARTICLES IN WHICH DEFINED
- -------------------------                        -------------------------

<S>                                                  <C>
Taking Date                                          24.1

Tax Appeal                                           7.1.1(d)

Tenant                                               Introductory Paragraph
                                                     (page 1); 50.15

Tenant Design and Construction Process               Exhibit 'IC"

Tenant Electricity                                   7.1.3

Tenant Electricity Costs                             7.1.3

Tenant Work                                          4.2

Tenant's Address                                     1.9(a)

Tenant's Centerpointe I Proportionate Share          7.1.1(a), 50.16.1

Tenant's Centerpointe II Proportionate Share         7.1.1(b), 50.16.2

Tenant's Control Area                                52.1

Tenant's Proportionate Share                         50.16

Term                                                 3.1

Termination Date                                     3.1

Three Year Average Assessment                        7.1.1(e)

Wilson Boulevard Lease                               4.3
</TABLE>

                                      I-5

<PAGE>

                                   EXHIBIT J

                              MEMORANDUM OF LEASE

         THIS MEMORANDUM OF LEASE is made as of this ________ day of August,
1992, by and between JOSHUA REALTY CORPORATION, a Delaware corporation
("Landlord"), and AMERICAN MANAGEMENT SYSTEMS, INC., a Delaware corporation
('Tenant"), with respect to the following recitals:

         A.      Landlord is the owner of the land and improvements located in
Fairfax County, Virginia at 4050 and 4000 Legato Road, as more fully described
in Exhibit A attached hereto.

         B.      Pursuant to a lease of even date herewith (the "Lease'),
Landlord has leased to Tenant all of the rentable area of the building situated
at 4050 Legato Road and approximately 38,384 square feet of rentable area in
the building situated at 4000 Legato Road.  The Lease grants Tenant certain
expansion rights in the building situated at 4000 Legato Road.

         C.      Landlord and Tenant desire to provide record notice of the
Lease.

         NOW THEREFORE, in consideration of the premises and other good and
adequate consideration, receipt of which is acknowledged, Landlord and Tenant
agree and acknowledge as follows:

         1.      Landlord and Tenant have entered into the Lease.

         2.      The initial term of the Lease is for fifteen (15) years
                 commencing on the date hereof.  The Lease grants Tenant the
                 option to extend the term of the Lease for two (2) five-year
                 renewal periods.

         3.      This Memorandum of Lease describes certain provisions
                 contained in the Lease.  Reference is hereby made to the Lease
                 for the complete statement of all terms and conditions
                 contained therein.

         4.      In no event shall this Memorandum of Lease be used to
                 interpret or construe the terms of the Lease, the sole purpose
                 of this Memorandum of Lease being to provide recordable notice
                 of the Lease.

                                      J-1

<PAGE>

         IN WITNESS WHEREOF, Landlord and Tenant have caused this Memorandum of
Lease to be executed and delivered as of the date and year first above written.

ATTEST:                                     Landlord:

                                            JOSHUA REALTY CORPORATION,
                                            a Delaware corporation

                                            By:
--------------------------------                --------------------------------
      (Corporate Seal)                         Steven D. Burton, Vice President

                                            Tenant:

                                            AMERICAN MANAGEMENT SYSTEMS, INC.,
                                            a Delaware corporation

                                            By:
--------------------------------                --------------------------------
      (Corporate Seal)
                                            Title:
                                                  -----------------------------

Title:

                                      J-2
<PAGE>

                     FIRST AMENDMENT TO AGREEMENT OF LEASE
                     BETWEEN JOSHUA REALTY CORPORATION AND
                       AMERICAN MANAGEMENT SYSTEMS, INC.

         This First Amendment to Agreement of Lease is made this 24th day of
May, 1993, between JOSHUA REALTY CORPORATION, a Delaware corporation (general
partner and sole remaining partner of Faircenter Limited Partnership, a
Delaware limited partnership) (hereinafter referred to as "Landlord"), and
AMERICAN MANAGEMENT SYSTEMS, INC., a Delaware corporation (hereinafter referred
to as "Tenant").

                              B A C K G R O U N D:

         A.      Landlord and Tenant entered into a certain Agreement of Lease
dated August 10, 1992 (the "Lease").  Capitalized terms used in this First
Amendment and not defined shall have the meanings ascribed to them under the
Lease.

         B.      Tenant has exercised Tenant's option to lease the Expansion
Space pursuant to Paragraph 62 of the Lease.

         C.      Landlord and Tenant desire that Tenant lease from Landlord
approximately 2,893 square feet on the eighth floor of the Centerpointe II
Building and Landlord and Tenant agree to amend the Lease by adding Paragraph
66 to the Lease as hereinafter provided:

         66.     Eighth Floor Space.

                          66.1    Landlord hereby leases, to Tenant, and Tenant
                 hereby hires and takes from Landlord, approximately 2,893
                 square feet on the eighth floor of the Centerpointe II
                 Building which shall herein be defined as the "Eighth Floor
                 Space".  Landlord shall make available the Eighth Floor Space
                 to Tenant for Tenant Work upon the full execution of this
                 First Amendment.  All of the terms and condition of the Lease
                 applicable to the Premises shall apply to such Eighth Floor
                 Space, except as set forth below in this Article.  The Eighth
                 Floor Space shall be delivered to Tenant in its then "as-is"
                 condition and state of repair.

                          66.2    For purposes of the Eighth Floor Space, the
                 Concession Fund shall equal Eighteen Dollars ($18.00) per
                 rentable square foot.  All other provisions in the Lease
                 governing the Concession Fund shall apply to the Eighth Floor
                 Space.

                          66.3    The Term of the Lease shall commence as to
                 the Eighth Floor Space on May 1, 1993 ("Eighth Floor Space
                 Lease Commencement Date").

                          66.4    Tenant's obligation to pay Rent for the
                 Eighth Floor Space shall commence on March 1, 1994 ("Eighth
                 Floor Space Rent Commencement Date").  During the period
                 between the Eighth Floor Space Lease Commencement Date and the
                 Eighth Floor Space Rent Commencement Date, Tenant shall pay to
                 Landlord an amount equal to Five Dollars ($5.00) per rentable
                 square foot per annum, in equal monthly installments, in
                 advance, as Additional Rent hereunder.
<PAGE>
                 All other obligations of Tenant pertaining to the Eighth Floor
                 Space under the Lease shall commence on the Eighth Floor Space
                 Lease Commencement Date.

                          66.5    After the Eighth Floor Space Rent
                 Commencement Date, Tenant's Centerpointe II Proportionate
                 Share shall be increased by an amount equal to the percentage
                 derived by dividing the rentable square footage of the Eighth
                 Floor Space by 203,630.

                          66.6    Except as modified by this First Amendment,
                 the Lease shall otherwise remain in full force and effect.

         IN WITNESS WHEREOF, and intending to be legally bound hereby, the
parties hereto have executed this First Amendment to Lease on the date first
set forth herein.

                                  LANDLORD:

                                  JOSHUA REALTY CORPORATION,
                                  a Delaware corporation

                                  By:      /s/ Steven D. Burton
                                           --------------------------------
                                           Steven D. Burton, Vice President

                                  TENANT:

                                  AMERICAN MANAGEMENT SYSTEMS, INC.,
                                  a Delaware corporation

                                  By:      /s/ Frank A. Nicolai
                                           --------------------------------

                                  Title:
                                           --------------------------------
<PAGE>
- -----------------------

- -----------------------

         I, the undersigned Notary Public in and for the above-named
jurisdiction, hereby certify that Steven D. Burton, who executed the foregoing
memorandum of Lease dated August __, 1992 in his capacity as Vice President of
Joshua Realty Corporation, personally appeared before me in my aforesaid
jurisdiction and acknowledged the same as his free act and deed and the act and
deed of said corporation.

                                  ----------------------------------
                                  Notary Public               [SEAL]

                                  My commission expires:

                                  ----------------------------------

- -----------------------

- -----------------------

         I, the undersigned Notary Public in and for the above-named
jurisdiction, hereby certify that _________________, who executed the foregoing
Memorandum of Lease dated August __, 1992 in his capacity as [Vice] President
of American Management Systems, Inc., personally appeared before me in my
aforesaid jurisdiction and acknowledged the same as his free act and deed and
the act and deed of said corporation.

                                  ----------------------------------
                                  Notary Public               [SEAL]

                                  My commission expires:

                                  ----------------------------------
<PAGE>
                     SECOND AMENDMENT TO AGREEMENT OF LEASE
                     BETWEEN JOSHUA REALTY CORPORATION AND
                       AMERICAN MANAGEMENT SYSTEMS, INC.

                 This Second Amendment to Agreement of Lease is made this 18th
day of March, 1994, between JOSHUA REALTY CORPORATION, a Delaware corporation
(general partner and sole remaining partner of Faircenter Limited Partnership,
a Delaware limited partnership) (hereinafter referred to as "Landlord"), and
AMERICAN MANAGEMENT SYSTEMS, INC., a Delaware corporation (hereinafter referred
to as "Tenant").

                              B A C K G R 0 U N D:

                 A.       Landlord and Tenant entered into a certain Agreement
of Lease dated August 10, 1992, as amended by a First Amendment to Agreement of
Lease dated May 24, 1993 (together the "Lease").  Capitalized terms used in
this Second Amendment and not defined shall have the meanings ascribed to them
under the Lease.

                 B.       Landlord and Tenant desire to amend and restate
Article 6.3 of the Lease to modify the basis upon which the escalation of Base
Rent may occur during the Term of the Lease.

                 NOW THEREFORE, for good and valuable consideration, the
receipt and sufficiency of which are hereby acknowledged, Landlord and Tenant
amend the Lease by amending and restating Article 6.3 as hereinafter provided:

                          "6.3    Escalation of Base Rent.

                                  6.3.1  Commencing on May 1, 1994 ("Escalation
                          Date"), and on the first day of May during the Term
                          thereafter (each a "Subsequent Escalation Date")
                          (each such period from and after the Escalation Date
                          to the date which is one day prior to the next
                          Subsequent Escalation Date being herein defined as an
                          "Escalation Period"), subject to Article 6.3.2 below,
                          Base Rent per rentable square foot shall be increased
                          for each Escalation Period by an amount equal to
                          Three and Eight Hundred Twenty-five one thousandths
                          percent (3.825%) (the "Escalation Percentage")
                          multiplied by the difference between (i) Base Rent
                          per rentable square foot, at the rate effective on
                          the day before the applicable Subsequent Escalation
                          Date and (ii) the sum of the Base Year Operating
                          Expenses and Base Year Real Estate Taxes
<PAGE>
                          per rentable square foot.  By way of illustration of
                          the foregoing formula, if the sum of the Base Year
                          Operating Expenses and Base Year Real Estate Taxes
                          per rentable square foot is Four Dollars and
                          Forty-five cents ($4.45), then on the Escalation Date
                          Base Rent per rentable square foot will increase to
                          $14.05 per rentable square foot from and after the
                          Escalation Date until the next Subsequent Escalation
                          Date.

                                  6.3.2   The selection of an Escalation
                          Percentage of Three and Eight Hundred Twenty-five one
                          thousandths percent (3.825%) assumes that the sum of
                          the Base Year Operating Expenses and the Base Year
                          Real Estate Taxes will equal Four Dollars and
                          Forty-five cents ($4.45). The Escalation Percentage
                          will be adjusted if the actual sum of Base Year
                          Operating Expenses and Base Year Real Estate Taxes is
                          not four Dollars and Forty-five Cents ($4.45) to that
                          percentage which will produce a series of Base Rent
                          cash flows, the net present value of which shall
                          equal the net present value of Base Rent over the
                          primary term of the Lease, as defined in the Lease
                          prior to this Second Amendment, using a discount rate
                          in both net present value calculations equal to eight
                          percent (8%).  The Escalation Percentage will also be
                          readjusted if, pursuant to Article 7.1.1(e) of the
                          Lease, the Base Year Real Estate Taxes are
                          subsequently adjusted.  Schedule A attached to this
                          Second Amendment illustrates the manner in which the
                          Escalation Percentage may be adjusted in the event
                          that the actual sum of Base Year operating Expenses
                          and Base Year Real Estate Taxes is not Four Dollars
                          and Forty-five Cents ($4.45)."

                 IN WITNESS WHEREOF, and intending to be legally bound hereby,
the parties hereto have executed this Second Amendment to Lease on the date
first set forth herein.  Except as amended hereby, the Lease remains in full
force and effect.

                                  LANDLORD:

                                  JOSHUA REALTY CORPORATION,
                                  a Delaware corporation

                                  By:  /s/ Steven D. Burton
                                       ----------------------
                                       Steven D. Burton, Vice
                                       President

                      [SIGNATURES CONTINUED ON NEXT PAGE]
<PAGE>
                   [SIGNATURES CONTINUED FROM PREVIOUS PAGE]

                                  TENANT:

                                  AMERICAN MANAGEMENT SYSTEMS, INC.,
                                  a Delaware corporation

                                  By: /s/ Frank A. Nicolai
                                      ------------------------------

                                  Title:  Executive Vice President
                                          --------------------------
<PAGE>
Schedule A

<TABLE>
<CAPTION>
INITIAL ESCALATION                                                                  260,000 square feet
         Base Year Taxes & Expenses         $4.45
         Per Square Foot                    $9.25
         Rate of escalation                3.825%

         Interest Rate                        8.0                               YEARS
                        NPV            1            2            3            4            5            6
                ----------------------------------------------------------------------------------------------------------
<S>              <C>           <C>         <C>           <C>          <C>          <C>          <C>
Current Lease    25,715,912    2,405,000    2,459,113    2,514,443    2,571,017    2,618,885    2,948,015
Proposed Terms   25,715,912    2,405,000    2,496,982    2,592,483    2,691,635    2,794,580    2,901,463
- --------------------------------------------------------------------------------------------------------------------------
</TABLE>

<TABLE>
<CAPTION>
INITIAL ESCALATION
         Base Year Taxes & Expenses         $4.45
         Per Square Foot                    $9.25
         Rate of escalation                3.825%

         Interest Rate                        8.0                               YEARS
                         7            8            9           10           11           12
                ----------------------------------------------------------------------------------------------------------
<S>              <C>          <C>          <C>          <C>          <C>          <C>
Current Lease    3,014,345    3,082,168    3,151,517    3,222,426     3,814,30    3,900,766
Proposed Terms   3,012,433    3,127,647    3,247,268    3,371,464    3,500,410    3,634,287
- ---------------------------------------------------------------------------------------------------------------------------
</TABLE>

<TABLE>
<CAPTION>
INITIAL ESCALATION
         Base Year Taxes & Expenses         $4.45
         Per Square Foot                    $9.25
         Rate of escalation                3.825%

         Interest Rate                        8.0                  YEARS
                        13          14           15
                ----------------------------------------------------------------------------------------------------------
<S>              <C>         <C>         <C>
Current Lease    3,988,534   4,078,276    4,170,037
Proposed Terms   3,773,285   3,917,600    4,067,433
- --------------------------------------------------------------------------------------------------------------------------
</TABLE>

<TABLE>
<CAPTION>
- --------------------------------------------------------------------------------------------------------------------------
Example #1
         Base Year Taxes & Expenses         $4.60
         Per Square Foot                    $9.10
         Rate of escalation                3.849%

         Interest Rate                        8.0                               YEARS
                        NPV            1            2            3            4            5            6
                ----------------------------------------------------------------------------------------------------------
<S>              <C>           <C>         <C>          <C>          <C>          <C>          <C>
Current Lease    25,336,182    2,366,000    2,419,235    2,473,668    2,529,325    2,586,235    2,904,425
Proposed Terms   25,336,182    2,366,000     2,457,08    2,551,641    2,649,854    2,751,847    2,857,766
- --------------------------------------------------------------------------------------------------------------------------
</TABLE>

<TABLE>
<CAPTION>
- --------------------------------------------------------------------------------------------------------------------------
Example #1
         Base Year Taxes & Expenses         $4.60
         Per Square Foot                    $9.10
         Rate of escalation                3.849%

         Interest Rate                        8.0                               YEARS
                         7            8            9           10           11           12
                ----------------------------------------------------------------------------------------------------------
<S>              <C>          <C>         <C>          <C>          <C>          <C>
Current Lease    2,969,775    3,036,595    3,104,918    3,174,779    3,766,212    3,850,951
Proposed Terms   2,967,762    3,081,991    3,200,618    3,323,810    3,451,744    3,584,602
- --------------------------------------------------------------------------------------------------------------------------
</TABLE>

<TABLE>
<CAPTION>
- --------------------------------------------------------------------------------------------------------------------------
Example #1
         Base Year Taxes & Expenses         $4.60
         Per Square Foot                    $9.10
         Rate of escalation                3.849%

         Interest Rate                        8.0                YEARS
                        13          14           15
                ----------------------------------------------------------------------------------------------------------
<S>              <C>         <C>          <C>
Current Lease    3,937,598   4,026,194    4,116,783
Proposed Terms   3,722,574   3,885,856    4,014,653
- --------------------------------------------------------------------------------------------------------------------------
</TABLE>

<TABLE>
<CAPTION>
- --------------------------------------------------------------------------------------------------------------------------
Example #2
         Base Year Taxes & Expenses         $4.75
         Per Square Foot                    $8.95
         Rate of escalation                3.880%

         Interest Rate                        8.0                               YEARS
                        NPV            1            2            3            4            5            6
                ----------------------------------------------------------------------------------------------------------
<S>              <C>           <C>         <C>          <C>          <C>          <C>          <C>
Current Lease    24,956,453    2,327,000    2,379,358    2,432,893    2,487,633    2,543,605    2,860,836
Proposed Terms   24,965,453    2,327,000    2,417,291    2,511,085    2,608,519    2,709,733    2,814,874
- --------------------------------------------------------------------------------------------------------------------------
</TABLE>

<TABLE>
<CAPTION>
- --------------------------------------------------------------------------------------------------------------------------
Example #2
         Base Year Taxes & Expenses         $4.75
         Per Square Foot                    $8.95
         Rate of escalation                3.880%

         Interest Rate                        8.0                               YEARS
                         7            8            9           10           11           12
                ----------------------------------------------------------------------------------------------------------
<S>              <C>          <C>          <C>          <C>          <C>          <C>
Current Lease    2,925,205    2,991,022    3,058,320    3,127,132    3,717,493    3,801,136
Proposed Terms   2,924,095    3,037,554    3,155,415    3,277,849    3,405,035    3,537,155
- --------------------------------------------------------------------------------------------------------------------------
</TABLE>

<TABLE>
<CAPTION>
- --------------------------------------------------------------------------------------------------------------------------
Example #2
         Base Year Taxes & Expenses         $4.75
         Per Square Foot                    $8.95
         Rate of escalation                3.880%

         Interest Rate                        8.0                YEARS
                        13          14           15
                ----------------------------------------------------------------------------------------------------------
<S>              <C>         <C>         <C>
Current Lease    3,886,662   3,974,112    4,063,529
Proposed Terms   3,674,401   3,816,973    3,965,077
- --------------------------------------------------------------------------------------------------------------------------
</TABLE>

<TABLE>
<CAPTION>
- --------------------------------------------------------------------------------------------------------------------------
Example #3
         Base Year Taxes & Expenses         $4.30
         Per Square Foot                    $9.40
         Rate of escalation                3.801%

         Interest Rate                        8.0                               YEARS
                        NPV            1            2            3            4            5            6
                ----------------------------------------------------------------------------------------------------------
<S>              <C>           <C>          <C>          <C>          <C>          <C>          <C>
Current Lease    26,095,641    2,444,000    2,498,990    2,555,217    2,612,710    2,671,496    2,991,604
Proposed Terms   26,095,641    2,444,000    2,536,896    2,633,323    2,733,414    2,837,311    2,945,156
- --------------------------------------------------------------------------------------------------------------------------
</TABLE>

<TABLE>
<CAPTION>
- --------------------------------------------------------------------------------------------------------------------------
Example #3
         Base Year Taxes & Expenses         $4.30
         Per Square Foot                    $9.40
         Rate of escalation                3.801%

         Interest Rate                        8.0                               YEARS
                         7            8            9           10           11           12
                ----------------------------------------------------------------------------------------------------------
<S>              <C>          <C>          <C>          <C>          <C>          <C>
Current Lease    3,058,915    3,127,741    3,198,115    3,270,073    3,863,649    3,950,581
Proposed Terms   3,057,101    3,173,300    3,293,917    3,419,117    3,549,077    3,683,977
- --------------------------------------------------------------------------------------------------------------------------
</TABLE>

<TABLE>
<CAPTION>
- --------------------------------------------------------------------------------------------------------------------------
Example #3
         Base Year Taxes & Expenses         $4.30
         Per Square Foot                    $9.40
         Rate of escalation                3.801%

         Interest Rate                        8.0                 YEARS
                        NPV           13          14           15
                ----------------------------------------------------------------------------------------------------------
<S>              <C>           <C>        <C>          <C>
Current Lease    26,095,641    4,039,470   4,130,358    4,223,291
Proposed Terms   26,095,641    3,824,004   3,969,353    4,120,227
- --------------------------------------------------------------------------------------------------------------------------
</TABLE>
<PAGE>
                     THIRD AMENDMENT TO AGREEMENT OF LEASE
                     BETWEEN JOSHUA REALTY CORPORATION AND
                       AMERICAN MANAGEMENT SYSTEMS, INC.

         This Third Amendment to Agreement of Lease is made this 5th day of
June, 1995, between JOSHUA REALTY CORPORATION, a Delaware corporation (general
partner and sole remaining partner of Faircenter Limited Partnership, a
Delaware limited partnership) (hereinafter referred to as "Landlord"), and
AMERICAN MANAGEMENT SYSTEMS, INC., a Delaware corporation (hereinafter referred
to as "Tenant").

                                   BACKGROUND

         A.      Landlord and Tenant entered into a certain Agreement of Lease
dated August 10, 1992, as amended by a First Amendment to Agreement of Lease
dated May 24, 1993 and by a Second Amendment to Agreement of Lease dated March
18, 1994 (as amended, the "Lease").  Capitalized terms used in this Third
Amendment and not deemed shall have the meanings ascribed to them under the
Lease.

         B.      Landlord and Tenant desire that Tenant lease from Landlord
approximately 4,393 rentable square feet on the fifth floor of the Centerpointe
II Building and Landlord and Tenant agree to amend the Lease by adding
Paragraph 67 to the Lease as hereinafter provided:

                 67.      Fifth Floor Space.

                          67.1    Landlord hereby leases to Tenant, and Tenant
                 hereby hires and takes from Landlord, approximately 4,393
                 rentable square feet on the fifth floor of the Centerpointe II
                 Building more fully described on the floor plan annexed to
                 this Third Amendment as Exhibit A, which shall herein be
                 deemed as the "Fifth Floor Space." Landlord shall make
                 available the Fifth Floor Space to Tenant for Tenant Work on
                 June 1, 1995.  All of the terms and conditions of the Lessee
                 applicable to the Premises shall apply to such Fifth Floor
                 Space, except as set forth below in this Article.

                          67.2.1   The Fifth Floor Space will be delivered to
                 Tenant in its "as is", "as built" condition and state of
                 repair.  Any mixtures not removed by the prior tenant shall be
                 left in place and not removed by Landlord.  Tenant shall
                 perform the Fifth Floor Tenant's Work (which term shall mean
                 the provision of materials, components, labor and services
                 encompassed within the work described on Exhibit B to this
                 Third Amendment) (i) at Tenant's sole cost, except as provided
                 in Paragraph
<PAGE>
                 67,2.2, and (ii) in accordance with the Tenant Design and
                 Construction Process set forth on Exhibit "C" to the Lease and
                 otherwise in accordance with all relevant provisions of the
                 Lease.  To the extent required by law, Landlord will comply
                 with the requirements of the ADA applicable to the Core
                 Elements of Centerpointe H which may arise because of the
                 performance of the Fifth Floor Tenant's Work and Tenant shall
                 comply with all other ADA requirements respecting the Fifth
                 Floor Space, including those requirements arising from the
                 Fifth Floor Tenant's Work.

                          67.2.2  For purposes of the Fifth Floor Space, the
                          Concession Fund shall equal Seven Dollars ($7.00) per
                          rentable square foot.  All other provisions in the
                          Lease governing the Concession Fund shall apply to
                          the Fifth Floor Space.

                          67.3    The Term of the Lease shall commence as to
                          the Fifth Floor Space on June 1, 1995 ("Fifth Floor
                          Space Lease Commencement Date").  The Term of the
                          Lease as to the Fifth Floor Space shall expire on the
                          date which is four (4) years and seven (7) months
                          after the Fifth Floor Space Rent Commencement Date.

                          67.4    Base Rent payable for the Fifth Floor Space
                          shall be fifteen dollars and sixty cents ($15.60) per
                          rentable square foot, net of Electricity Costs, and
                          subject to adjustment as described in article 6.4.
                          Base Rent for the Fifth Floor Space shall be payable
                          as provided in Section 6.1.1. Tenant's obligation to
                          pay Rent for the Fifth Floor Space shall commence_on
                          the earlier of (i) July 15, 1994 or (ii) substantial
                          completion of the Fifth Floor Tenant's Work ("Fifth
                          Floor Space Rent Commencement Date").  All other
                          obligations of Tenant pertaining to the Fifth Floor
                          Space under the Lease shall commence on the Fifth
                          Floor Space Rent Commencement Date.  If the Fifth
                          Floor Space Rent Commencement Date is other than the
                          First day of a month, Base Rent for the Fifth Floor
                          Space due from the Fifth Floor Space Rent
                          Commencement Date until the first day of the
                          following month shall be prorated and payable on the
                          Fifth Floor Space Rent Commencement Date.

                          67.5    After the Fifth Floor Space Rent Commencement
                          Date, Tenant's Centerpointe II Proportionate Share
                          shall be increase by an amount equal to the
<PAGE>
                          percentage derived by dividing the rentable square
                          footage of the Fifth Floor Space by 204,481.
                          Therefore, after the Fifth Floor Space Rent ,
                          Tenant's Centerpointe H Proportionate Share shall
                          equal 31.40%.

                          67.6    Except as modified by this Third Amendment,
                          the Lease shall otherwise remain in full force and
                          effect.

         IN WITNESS WHEREOF, and intending to be legally bound hereby, the
parties hereto have executed this Third Amendment to Lease on the date on the
date first set forth herein.

                                  LANDLORD:

                                  JOSHUA REALTY CORPORATION,
                                  a Delaware Corporation

                                  By:  /s/    Gerald Karr
                                       -----------------------
                                       Name:  Gerald Karr
                                       Title: Vice President

                                  TENANT:

                                  AMERICAN MANAGEMENT SYSTEMS, INC.,
                                  a Delaware Corporation

                                  By:  /s/    Frank A. Nicolai
                                       -----------------------
                                       Name:  Frank A. Nicolai
                                       Title: EVP

[THE FOLLOWING PAGES INCLUDED AS EXHIBITS A AND B FLOOR PLANS OF THE PREMISES.]
<PAGE>
                     FOURTH AMENDMENT TO AGREEMENT OF LEASE
                     BETWEEN JOSHUA REALTY CORPORATION AND
                       AMERICAN MANAGEMENT SYSTEMS, INC.

                 This Fourth Amendment to Agreement of Lease is made this 18th
day of July, 1995, between JOSHUA REALTY CORPORATION, a Delaware corporation
(general partner and sole remaining partner of Faircenter Limited Partnership,
a Delaware limited partnership) (hereinafter referred to as "Landlord"), and
AMERICAN MANAGEMENT SYSTEMS, INC., a Delaware corporation (hereinafter referred
to as "Tenant").

                                   BACKGROUND

                 A.       Landlord and Tenant entered into a certain Agreement
of Lease dated August 10, 1992, as amended by a First Amendment to Agreement of
Lease dated May 24, 1993, by a Second Amendment to Agreement of Lease dated
March 18, 1994 and by a Third Amendment to Agreement of Lease Dated June 5,
1995 (as amended, the "Lease").  Capitalized terms used in this Fourth
Amendment and not defined shall have the meanings ascribed to them under the
Lease.

                 B.       Landlord and Tenant desire that Tenant lease from
Landlord approximately 1,697 rentable square feet on the ninth floor of the
Centerpointe II Building known as suite 940 and Landlord and Tenant agree to
amend the Lease by adding Paragraph 68 to the Lease as hereinafter provided:

                 68.      Ninth Floor Space.

                          68.1    Landlord hereby leases to Tenant, and Tenant
                 hereby hires and takes from Landlord, approximately 1,697
                 rentable square feet on the ninth floor of the Centerpointe II
                 Building more fully described on the floor plan annexed to
                 this Fourth Amendment as Exhibit A, which shall herein be
                 deemed as the "Suite 940." Landlord shall make available Suite
                 940 to Tenant for Tenant Work on July 1, 1995.  All of the
                 terms and conditions of the Lease applicable to the Premises
                 shall apply to Suite 940, except as set forth below in this
                 Article.

                          68.2.1  Suite 940 will be delivered to Tenant in its
                 "as is "as built" condition and state of repair.  Any mixtures
                 not removed by the prior tenant shall be left in place and not
                 removed by Landlord.  Tenant shall perform Suite 940 Tenant's
                 Work (which term shall mean the provision of materials,
                 components, labor and services encompassed within the work
                 described on Exhibit B to this Fourth Amendment) (i) at
                 Tenant's sole
<PAGE>
                 cost, except as provided in Paragraph 68.2.2, and (H) in
                 accordance with the Tenant Design and Construction Process set
                 forth on Exhibit "C" to the Lease and otherwise in accordance
                 with all relevant provisions of the Lease.  To the extent
                 required by law, Landlord will comply with the requirements of
                 the ADA applicable to the Core Elements of Centerpointe 11
                 which may arise because of the performance of Suite 940
                 Tenant's Work and Tenant shall comply with all other ADA
                 requirements respecting Suite 940, including those
                 requirements arising from Suite 940 Tenant's Work.

                          68.2.2  For purposes of Suite 940, the Concession
                 Fund shall equal Seven Dollars ($7.00) per rentable square
                 foot.  All other provisions in the Lease governing the
                 Concession Fund shall apply to Suite 940.

                          68.3    The Term of the Lease shall commence as to
                 Suite 940 on July 1, 1995 ("Suite 940 Lease Commencement
                 Date").  The Term of Lease as to Suite 940 shall expire on the
                 date which is four (4) years after the Suite 940 Rent
                 Commencement Date.

                          68.4    Base Rent payable for Suite 940 shall be
                 fifteen dollars and sixty cents ($15.60) per rentable square
                 foot, net of Electricity Costs, and subject to adjustment as
                 described in article 6.4. Base Rent for Suite 940 shall be
                 payable as provided in Section 6.1.1. Tenant's obligation to
                 pay Rent for Suite 940 shall commence on the earlier of (i)
                 August 1, 1995 or 00 substantial completion of Suite 940
                 Tenant's Work ("Suite 940 Rent Commencement Date").  All other
                 obligations of Tenant pertaining to Suite 940 under the Lease
                 shall commence on the date of this Fourth Amendment.  If the
                 Suite 940 Rent Commencement Date is other than the first day
                 of a month, Base Rent for Suite 940 due from the Suite 940
                 Rent Commencement Date until the first day of the following
                 month shall be prorated and payable on the Suite 940 Rent
                 Commencement Date.

                          68.5    After the Suite 940 Rent Commencement Date,
                          Tenant's Centerpointe H Proportionate Share shall be
                          increase by an amount equal to the percentage derived
                          by dividing the rentable square footage of Suite 940
                          by 204,481.  Therefore, after the Suite
<PAGE>
                          940 Rent Commencement, Tenant's Centerpointe H
                          Proportionate Share shall equal 32.23%.

                          68.6 Except as modified by this Fourth Amendment, the
                          Lease shall otherwise remain in full force and
                          effect.

                 IN WITNESS WHEREOF, and intending to be legally bound hereby,
the parties hereto have executed this Fourth Amendment to Lease on the date on
the date first set forth herein.

                                  LANDLORD:

                                  JOSHUA Realty CORPORATION,
                                  a Delaware corporation

                                  By: /s/    Dan Coughlan
                                      ------------------------
                                      Name:  Dan Coughlan
                                      Title: V.P.

                                  TENANT:

                                  AMERICAN MANAGEMENT SYSTEMS, INC.,
                                  a Delaware Corporation

                                  By: /s/    Frank A. Nicolai
                                      ------------------------
                                      Name:  Frank A. Nicolai
                                      Title: EVP, Secretary &
                                      Treasurer
<PAGE>
                     FIFTH AMENDMENT TO AGREEMENT OF LEASE
                     BETWEEN JOSHUA REALTY CORPORATION AND
                       AMERICAN MANAGEMENT SYSTEMS, INC.

                 This Fifth Amendment to Agreement of Lease is made this 27th
day of December, 1995, between JOSHUA REALTY CORPORATION, a Delaware
corporation (general partner and sole remaining partner of Faircenter Limited
Partnership, a Delaware limited partnership) (hereinafter referred to as
"Landlord"), and AMERICAN MANAGEMENT SYSTEMS, INC., a Delaware corporation
(hereinafter referred to as "Tenant").

                                   BACKGROUND

                 A.       Landlord and Tenant entered into a certain Agreement
of Lease dated August 10, 1992, as amended by a First Amendment to Agreement of
Lease dated May 24, 1993, by a Second Amendment to Agreement of Lease dated
March 18, 1994, by a Third Amendment to Agreement of Lease Dated June 5, 1995
and by a Fourth Amendment to Agreement of Lease Dated June 18, 1995 (as
amended, the "Lease").  Capitalized terms used in this Fifth Amendment and not
defined shall have the meanings ascribed to them under the Lease.

                 B.       Landlord and Tenant desire that Tenant lease from
Landlord approximately 3,687 rentable square feet on the ninth floor of the
Centerpointe II Building known as suite 960 and Landlord and Tenant agree to
amend the Lease by adding Paragraph 69 to the Lease as hereinafter provided:

                          69.     Ninth Floor Space.

                                  69.1     Landlord hereby leases to Tenant,
                          and Tenant hereby hires and takes from Landlord,
                          approximately 3,687 rentable square feet on the ninth
                          floor of the Centerpointe II Building more fully
                          described on the floor plan annexed to this Fifth
                          Amendment as Exhibit A, which shall herein be deemed
                          as the "Suite 960." Landlord shall make available
                          Suite 960 to Tenant for Tenant Work on January 1,
                          1996.  All of the terms and conditions of the Lease
                          applicable to the Premises shall apply to Suite 960,
                          except as set forth below in this Article.

                           69.2.1          Suite 960 will be delivered to
                          Tenant in its "as is", "as built" condition and state
                          of repair.  Any fixtures not removed by the prior
                          tenant shall be left in place and not removed by
                          Landlord.  Tenant shall perform Suite 960's
<PAGE>
                          Tenant's Work (which term shall mean the provision of
                          materials, components, labor and services encompassed
                          within the work described on Exhibit B to this Fifth
                          Amendment) (i) at Tenant's sole cost, except as
                          provided in Paragraph 69.2.2, and (ii) in accordance
                          with the Tenant Design and Construction Process set
                          forth on Exhibit "C" to the Lease and otherwise in
                          accordance with all relevant provisions of the Lease.
                          To the extent required by law, Landlord will comply
                          with the requirements of the ADA applicable to the
                          Core Elements of Centerpointe II which may arise
                          because of the performance of Suite 960 Tenant's Work
                          and Tenant shall comply with all other ADA
                          requirements respecting Suite 960, including those
                          requirements arising from Suite 960 Tenant's Work.

                                  69.2.2   For purposes of Suite 960, the
                          Concession Fund shall equal Zero Dollars ($0.00) per
                          rentable square foot.

                                  69.3     The Term of the Lease shall commence
                          as to Suite 960 on January 1, 1996 ("Suite 960 Lease
                          Commencement Date").  The Term of Lease as to Suite
                          960 shall expire on the date which is two (2) years
                          after the Suite 960 Rent Commencement Date.

                                  69.4     Base Rent payable for Suite 960
                          shall be twenty-two dollars and thirty, cents
                          ($22.30) per rentable square foot, net of Electricity
                          Costs, and subject to adjustment as described in
                          article 6.4.  Base Rent for Suite 960 shall be
                          payable as provided in Section 6.1.1.  Tenant's
                          obligation to pay Rent for Suite 960 shall commence
                          on the earlier of (i) February 15, 1995 or (ii)
                          substantial completion of Suite 960 Tenant's Work
                          ("Suite 960 Rent Commencement Date").  All other
                          obligations of Tenant pertaining to Suite 960 under
                          the Lease shall commence on the date of this Fourth
                          Amendment.  If the Suite 960 Rent Commencement Date
                          is other than the first day of a month, Base Rent for
                          Suite 960 due from the Suite 960 Rent Commencement
                          Date until the first day of the following month shall
                          be prorated and payable on the Suite 960 Rent
                          Commencement Date.

                                  69.5     After Suite 960 Rent Commencement
                          Date, Tenant's Centerpointe II Proportionate Share
                          shall be increase by an amount equal to the
                          percentage derived by dividing the rentable square
                          footage of
<PAGE>
                          Suite 960 by 204,481.  Therefore, after the Suite 960
                          Rent Commencement, Tenant's Centerpointe II
                          Proportionate Share shall equal 32.25%.

                                  69.6     If the Term of the Lease as to Suite
                          960 has not commenced by April 1, 1996, either party,
                          by written notice to the other given at any time
                          thereafter, but in all events prior to the Suite 960
                          Commencement Date, may terminate this Fifth
                          Amendment, in which event neither party shall have
                          any further rights or obligations under this Fifth
                          Amendment.

                                  69.7     Except as modified by this Fifth
                          Amendment, the Lease shall otherwise remain in full
                          force and effect.

                                  69.8     Notwithstanding anything contained
                          in this Fifth Amendment, if Landlord is unable to
                          make Suite 960 available to tenant by January 1, 1996
                          as a result of a hold over of the existing tenant of
                          Suite 960, then:  (i) the Suite 960 Lease
                          Commencement Date shall not be January 1, 1996 but
                          shall be such later date as Landlord shall advise
                          Tenant in writing following the vacation of Suite 960
                          by the current tenant, (ii) the validity of this
                          Fifth Amendment and the obligations of Tenant under
                          the Fifth Amendment shall not be affected by such
                          failure to deliver possession of Suite 960, except
                          that the Suite 960 Rent Commencement Date shall
                          instead be the earlier of (A) forty-five days after
                          the Suite 960 Lease Commencement Date or (B)
                          substantial completion of the Suite 960 Tenant's
                          Work, and (iii) Tenant shall have no claim against
                          Landlord arising out of Landlord's failure or
                          inability to deliver possession of Suite 960 on the
                          date originally fixed therefor.
<PAGE>
                 IN WITNESS WHEREOF, and intending to be legally bound hereby,
the parties hereto have executed this Fifth Amendment to Lease on the date on
the date first set forth herein.

                                  LANDLORD:

                                  JOSHUA REALTY CORPORATION,
                                  a Delaware corporation

                                  By: /s/ Dan Coughlan
                                      ----------------------------------
                                      Name:  Dan Coughlan
                                      Title:

                                  TENANT:

                                  AMERICAN MANAGEMENT SYSTEMS, INC.,
                                  a Delaware Corporation

                                  By: /s/ Frank A. Nicolai
                                      ----------------------------------
                                      Name:   Frank A. Nicolai
                                      Title:  EVP, Secretary & Treasurer
<PAGE>
                     SIXTH AMENDMENT TO AGREEMENT OF LEASE
                     BETWEEN JOSHUA REALTY CORPORATION AND
                       AMERICAN MANAGEMENT SYSTEMS, INC.

                 This Sixth Amendment to Agreement of Lease is made this _____
day of ________, 1996, between JOSHUA REALTY CORPORATION, a Delaware
corporation (general partner and sole remaining partner of Faircenter Limited
Partnership, a Delaware limited partnership) (hereinafter referred to as
"Landlord"), and AMERICAN MANAGEMENT SYSTEMS, INC., a Delaware corporation
(hereinafter referred to as "Tenant").

                              B A C K G R 0 U N D:

                 A.       Landlord and Tenant entered into a certain Agreement
of Lease dated August 10, 1992, as amended by a First Amendment to Agreement of
Lease dated May 24, 1993, by a Second Amendment to Agreement of Lease dated
March 18, 1994, by a Third Amendment to Agreement of Lease dated June 5, 1995,
by a Fourth Amendment to Agreement of Lease dated June 18, 1995 and by a Fifth
Amendment to Agreement of Lease dated December 27, 1995 (as amended, the
"Lease").  Capitalized terms used in this Sixth Amendment and not defined shall
have the meanings ascribed to them under the Lease.

                 B.       Landlord and Tenant desire that Tenant lease from
Landlord approximately 28,359 additional rentable square feet on the tenth and
eleventh floors of the Centerpointe II Building and Landlord and Tenant agree
to amend the Lease by adding Article 70 to the Lease as hereinafter provided:

                          70.     Tenth/Eleventh Floor Space.

                                  70.1     Landlord hereby leases to Tenant,
                          and Tenant hereby hires and takes from Landlord,
                          approximately 28,359 rentable square feet on the
                          tenth and eleventh floors of the Centerpointe II
                          Building, as more fully described on the floor plan
                          annexed to this Amendment as Exhibit A, which shall
                          herein be defined as the "Tenth/Eleventh Floor
                          Space." All of the terms and conditions of the Lease
                          applicable to the Premises shall apply to such
                          Tenth/Eleventh Floor Space, except as set forth below
                          in this Article.

                                  70.2.1   The Tenth/Eleventh Floor Space will
                          be delivered to Tenant in its "as is", "as built"
                          condition and state of repair.  Any fixtures not
                          removed by the prior tenant shall be left in place
<PAGE>
                          and not removed by Landlord.  Tenant shall perform
                          all work necessary to install any tenant improvements
                          or otherwise necessary to prepare the Tenth/Eleventh
                          Floor Space (i) at Tenant's sole cost, except as
                          provided in Paragraph 70.2.2, and (ii) in accordance
                          with the Tenant Design and Construction Process set
                          forth on Exhibit 'IC" to the Lease and otherwise in
                          accordance with all relevant provisions of the Lease.
                          To the extent required by law, Landlord will comply
                          with the requirements of the ADA applicable to the
                          Core Elements of Centerpointe II which may arise
                          because of the performance of the Tenth/Eleventh
                          Floor Tenant's Work and Tenant shall comply with all
                          other ADA requirements respecting the Tenth/Eleventh
                          Floor Space, including those requirements arising
                          from the Tenth/Eleventh Floor Tenant's Work.

                                  70.2.2   For purposes of the Tenth/Eleventh
                          Floor Space, the Concession Fund shall equal Ten
                          Dollars ($10.00) per rentable square foot.  All other
                          provisions in the Lease governing the Concession Fund
                          shall apply to-the Tenth/Eleventh Floor Space.

                                  70.3     The Term of the Lease shall commence
                          as to the Tenth/Eleventh Floor Space on March 15,
                          1997 ("Tenth/Eleventh Floor Space Lease Commencement
                          Date"); provided, that if Landlord is unable to
                          deliver the Tenth/Eleventh Floor Space to Tenant by
                          March 15, 1997 for any reason whatever, including
                          without limitation by reason of the holding over of
                          any tenant, then the Tenth/Eleventh Floor Space Lease
                          Commencement Date shall be delayed until such time as
                          Landlord delivers such space to Tenant and Landlord
                          will have no liability to Tenant in any event for any
                          such delay.  The Term of the Lease as to the
                          Tenth/Eleventh Floor Space shall expire on the
                          Termination Date.  Notwithstanding anything contained
                          in this Amendment, if for any reason Landlord has not
                          delivered the Tenth/Eleventh Floor Space to Tenant by
                          July 1, 1997, then upon written notice from Tenant to
                          Landlord given at any time after July 1, 1997 and
                          prior to the date Landlord delivers the
                          Tenth/Eleventh Floor Space to Tenant, as its sole and
                          exclusive remedy, Tenant may terminate this Sixth
                          Amendment, whereupon this Amendment shall be null and
                          void and neither party
<PAGE>
                          shall have any further rights or obligations under
                          this Sixth Amendment.

                                  70.4     Base Rent payable for the
                          Tenth/Eleventh Floor Space shall be Twenty-One and
                          50/100 Dollars ($21.50) per rentable square foot,
                          inclusive of Electricity Costs, and subject to
                          adjustment as described in Article 6.3. Base Rent for
                          the Tenth/Eleventh Floor Space shall be payable as
                          provided in Section 6.1.1. Tenant's obligation to pay
                          Rent for the Tenth/Eleventh Floor Space and all other
                          obligations of Tenant pertaining to the
                          Tenth/Eleventh Floor Space under the Lease shall
                          commence on the Tenth/Eleventh Floor Space Lease
                          Commencement Date.  If the Tenth/Eleventh Floor Space
                          Lease Commencement Date is other than the first day
                          of a month, Base Rent for the Tenth/Eleventh Floor
                          Space due from the Tenth/Eleventh Floor Space Lease
                          Commencement Date until the first day of the
                          following month shall be prorated and payable on the
                          Tenth/Eleventh Floor Lease Commencement Date.

                                  70.5     After the Tenth/Eleventh Floor Space
                          Lease Commencement Date, Tenant's Centerpointe II
                          Proportionate Share shall be increased by an amount
                          equal to the percentage derived by dividing the
                          rentable square footage of the Tenth/Eleventh Floor
                          Space by 204,481.  Therefore, after the
                          Tenth/Eleventh Floor Space Lease Commencement Date,
                          Tenant's Centerpointe II Proportionate Share shall
                          equal 47.9%.

                                  70.6     Except as modified by this Sixth
                          Amendment, the Lease shall otherwise remain in full
                          force and effect.
<PAGE>
                 IN WITNESS WHEREOF, and intending to be legally bound hereby,
the parties hereto have executed this Sixth Amendment to Lease on the date
first set forth herein.

                                  LANDLORD:

                                  JOSHUA REALTY CORPORATION,
                                  a Delaware corporation

                                  By:
                                       -----------------------------
                                       Name:
                                       Title:

                                  TENANT:

                                  AMERICAN MANAGEMENT SYSTEMS, INC.,
                                  a Delaware corporation

                                  By:  /s/    Frank A. Nicolai
                                       -----------------------------
                                       Name:  Frank A. Nicolai
                                       Title: EVP, Sec. & Treasurer

[THE FOLLOWING PAGES INCLUDED AS EXHIBITS A AND B, FLOOR PLANS OF THE
PREMISES.]
<PAGE>
                    SEVENTH AMENDMENT TO AGREEMENT OF LEASE
                     BETWEEN JOSHUA REALTY CORPORATION AND
                       AMERICAN MANAGEMENT SYSTEMS, INC.

                 This Seventh Amendment to Agreement of Lease is made as of
this 22nd day of July, 1996, between JOSHUA REALTY CORPORATION, a Delaware
corporation (general partner and sole remaining partner of Faircenter Limited
Partnership, a Delaware limited partnership) (hereinafter referred to as
"Landlord"), and AMERICAN MANAGEMENT SYSTEMS, INC., a Delaware corporation
(hereinafter referred to as "Tenant").

                              B A C K G R O U N D:

                 A.       Landlord and Tenant entered into a certain Agreement
of Lease dated August 10, 1992, as amended by a First Amendment to Agreement of
Lease dated May 24, 1993, by a Second Amendment to Agreement of Lease dated
March 18, 1994, by a Third Amendment to Agreement of Lease dated June 5, 1995,
by a Fourth Amendment to Agreement of Lease dated June 18, 1995, by a Fifth
Amendment to Agreement of Lease dated December 27, 1995 and by a Sixth
Amendment to Agreement of Lease (undated) (as amended, the "Lease").
Capitalized terms used in this Seventh Amendment and not defined shall have the
meanings ascribed to them under the Lease.

                 B.       Landlord and Tenant desire that Tenant lease from
Landlord approximately 1,829 additional rentable square feet on the first floor
of the Centerpointe II Building and Landlord and Tenant agree to amend the
Lease by adding Article 71 to the Lease as hereinafter provided:

                 71.       First Floor Space.

                           71.1   Landlord hereby leases to Tenant, and Tenant
                 hereby hires and takes from Landlord, approximately 1,829
                 rentable square feet on the first floor of the Centerpointe II
                 Building, as more fully described on the floor plan annexed to
                 this Amendment as Exhibit Al which shall herein be defined as
                 the "First Floor Space." All of the terms and conditions of
                 the Lease applicable to the Premises shall apply to such First
                 Floor Space, except as set forth below in this Article.

                           71.2.1          The First Floor Space will be
                 delivered to Tenant in its "as is" , "as built" condition and
                 state of repair.  Any fixtures not removed by the prior tenant
                 shall be left in place and not removed by
<PAGE>
                 Landlord.  Tenant shall perform all work (the "First Floor
                 Tenant's Work") necessary to install any tenant improvements
                 or otherwise necessary to prepare the First Floor Space (i) at
                 Tenant's sole cost and (ii) in accordance with the Tenant
                 Design and Construction Process set forth on Exhibit 'IC" to
                 the Lease and otherwise in accordance with all relevant
                 provisions of the Lease.  To the extent required by law,
                 Landlord will comply with the requirements of the ADA
                 applicable to the Core Elements of Centerpointe II which may
                 arise because of the performance of the First Floor Tenant's
                 Work and Tenant shall comply with all other ADA requirements
                 respecting the First Floor Space, including those requirements
                 arising from the First Floor Tenant's Work.

                           71.2.2 For purposes of the First Floor Space, there
                 shall be no Concession Fund.

                           71.3   The Term of the Lease shall commence as to
                 the First Floor Space on July 22, 1996 ("First Floor Space
                 Lease Commencement Date").  The Term of the Lease as to the
                 First Floor Space shall expire on December 31, 2000.

                           71.4   Base Rent payable for the First Floor Space
                 shall be Nineteen Dollars ($19.00) per rentable square foot,
                 inclusive of Electricity Costs, and subject to adjustment as
                 described in Article 6.3. Base Rent for the First Floor Space
                 shall be payable as provided in Section 6.1.1. Tenant's
                 obligation to pay Rent for the First Floor Space shall
                 commence on August 1, 1996.

                           71.5   After the First Floor Space Lease
                 Commencement Date, Tenant's Centerpointe II Proportionate
                 Share shall be increased by an amount equal to the percentage
                 derived by dividing the rentable square footage of the First
                 Floor Space by 204,481.  Therefore, after the First Floor
                 Space Lease Commencement Date, Tenant's Centerpointe II
                 Proportionate Share shall equal 48.79%.

                           71.6   Except as modified by this Seventh Amendment,
                 the Lease shall otherwise remain in full force and effect.
<PAGE>
                 IN WITNESS WHEREOF, and intending to be legally bound hereby,
the parties hereto have executed this Seventh Amendment to Lease as of the date
first set forth herein.

                                  LANDLORD:

                                  JOSHUA REALTY CORPORATION,
                                  a Delaware corporation

                                  By: /s/    Dan Coughlan
                                      ------------------------------
                                      Name:  Daniel Coughlan
                                      Title:

                                  TENANT:

                                  AMERICAN MANAGEMENT SYSTEMS, INC.,
                                  a Delaware corporation

                                  By: /s/    Frank A. Nicolai
                                      ------------------------------
                                      Name:  Frank A. Nicolai
                                      Title: Executive Vice President

[THE FOLLOWING PAGE INCLUDED AS EXHIBIT A FLOOR PLAN OF THE PREMISES.]
<PAGE>
                     EIGHTH AMENDMENT TO AGREEMENT OF LEASE
                     BETWEEN JOSHUA REALTY CORPORATION AND
                       AMERICAN MANAGEMENT SYSTEMS, INC.

         This Eighth Amendment to Agreement of Lease is made as of this 12th
day of February, 1997 between JOSHUA REALTY CORPORATION, a Delaware corporation
(general partner and sole remaining partner of Faircenter Limited Partnership,
a Delaware limited partnership) (hereinafter referred to as "Landlord"),
AMERICAN MANAGEMENT SYSTEMS, INC., a Delaware corporation (hereinafter referred
to as "Tenant"), and QUALITY SYSTEMS, INC., a Virginia corporation ("QSI").

                              B A C K G R O U N D:

         A.      Landlord and Tenant entered into a certain Agreement of Lease
dated August 10, 1992, as amended by a First Amendment to Agreement of Lease
dated May 24, 1993, by a Second Amendment to Agreement of Lease dated March 18,
1994, by a Third Amendment to Agreement of Lease dated June 5, 1995, by a
Fourth Amendment to Agreement of Lease dated June 18, 1995, by a Fifth
Amendment to Agreement of Lease dated December 27, 1995, by a Sixth Amendment
to Agreement of Lease (undated) and by a Seventh Amendment to Agreement of
Lease dated July 22, 1996 (as amended, the "Lease").  Capitalized terms used in
this Eighth Amendment and not defined shall have the meanings ascribed to them
under the Lease.

         B.      Pursuant to the Sixth Amendment to Agreement of Lease dated
(undated) (the "Sixth Amendment"), Landlord and Tenant agreed that Tenant lease
from Landlord approximately 28,359 additional rentable square feet on the tenth
and eleventh floors of Centerpointe II Building, which space is currently
occupied by QSI and defined in the Sixth Amendment, Section 70.1 as the
"Tenth/Eleventh Floor Space."

         C.      Pursuant to the Sixth Amendment, the Term of the Lease for the
Tenth/Eleventh Floor Space was to commence March 15, 1997, which date is the
day following the expiration of the lease between Landlord and QSI dated
December 21, 1989 (the "QSI Lease").

         D.      Pursuant to a Termination Agreement of even date herewith
between Landlord and QSI, Landlord and QSI have agreed to terminate the QSI
Lease early, on February 17, 1997.

         E.      Landlord and Tenant desire that Tenant lease from Landlord the
Tenth/Eleventh Floor Space on February 18, 1997, which date is approximately
one (1) month earlier than the
<PAGE>
Tenth/Eleventh Floor Lease Commencement Date set forth in Section 70.3 of the
Sixth Amendment.

         NOW, THEREFORE, for good and valuable consideration, including the
mutual promises, covenants and agreements herein contained, the parties hereto
mutually covenant and agree that the Lease is hereby amended as follows:

         1.      Term.  The dated "March 15, 1997" set forth in the second and
fifth lines of Section 70.3 of the Sixth Amendment is hereby deleted in both
instances, and substituted in each instance in lieu thereof is the date
"February 18, 1997."

         2.      Base Rent.  Notwithstanding anything to the contrary set forth
in Section 70.4 of the Sixth Amendment, Base Rent during any portion of the
Term of the Lease for the Tenth/Eleventh Floor Space prior to March 15, 1997
shall equal Seventeen and 50/100 Dollars ($17.50) per rentable square foot of
the Tenth/Eleventh Floor Space per annum, inclusive of Electricity Costs, and
not subject to adjustment as described in Section 6.3 of the Lease.  Commencing
March 15, 1997, Base Rent for the Tenth/Eleventh Floor Space shall be payable
in accordance with Section 70.4 of the Sixth Amendment.

         3.      Effect.  Except as modified by this Eighth Amendment, the
Lease shall otherwise remain in full force and effect.

<PAGE>
         IN WITNESS WHEREOF, and intending to be legally bound hereby, the
parties hereto have executed this Eighth Amendment to Lease as of the date
first set forth herein.

                                  LANDLORD:

                                  JOSHUA REALTY CORPORATION,
                                  a Delaware corporation

                                  By:  /s/    Dan Coughlan
                                       -----------------------------
                                       Name:  Daniel P. Coughlan
                                       Title:

                                  TENANT:

                                  AMERICAN MANAGEMENT SYSTEMS, INC.,
                                  a Delaware corporation

                                  By:  /s/    Frank A. Nicolai
                                       -----------------------------
                                       Name:  Frank A. Nicolai
                                       Title:

                                  QSI:

                                  QUALITY SYSTEMS, INC.,
                                  a Virginia corporation

                                  By:  /s/    Dan O'Neill
                                       -----------------------------
                                       Name:  Dan O'Neill
                                       Title: VP, Finance & Admin.
<PAGE>
                     NINTH AMENDMENT TO AGREEMENT OF LEASE
                     BETWEEN JOSHUA REALTY CORPORATION AND
                       AMERICAN MANAGEMENT SYSTEMS, INC.

         This Ninth Amendment to Agreement of Lease is made as of this 4th day
of March, 1997 between JOSHUA REALTY CORPORATION, a Delaware corporation
(general partner and sole remaining partner of Faircenter Limited Partnership,
a Delaware limited partnership) (hereinafter referred to as "Landlord") and
AMERICAN MANAGEMENT SYSTEMS, INC., a Delaware corporation (hereinafter referred
to as "Tenant").

                              B A C K G R O U N D:

         A.      Landlord and Tenant entered into a certain Agreement of Lease
dated August 10, 1992, as amended by a First Amendment to Agreement of Lease
dated May 24, 1993, by a Second Amendment to Agreement of Lease dated March 18,
1994, by a Third Amendment to Agreement of Lease dated June 5, 1995, by a
Fourth Amendment to Agreement of Lease dated June 18, 1995, by a Fifth
Amendment to Agreement of Lease dated December 27, 1995, by a Sixth Amendment
to Agreement of Lease (undated) and by a Seventh Amendment to Agreement of
Lease dated July 22, 1996 and by an Eighth Amendment to Agreement of Lease
dated as of February 12, 1997 (as amended, the "Lease").  Capitalized terms
used in this Ninth Amendment and not defined shall have the meanings ascribed
to them under the Lease.

         B.      Landlord and Tenant desire that Tenant lease from Landlord,
Suite 900, containing approximately 5,664 additional rentable square feet on
the ninth floor of the Counterpointe II Building and Landlord and Tenant agree
to amend the Lease by adding Article 72 to the Lease as hereinafter provided:

         72.     Suite 900 Space.

                          72.1  Landlord hereby leases to Tenant, and Tenant
                 hereby hires and takes from Landlord, approximately 5,664
                 rentable square feet on the ninth floor of the Centerpointe II
                 Building, as more fully described on the floor plan annexed to
                 this Amendment as Exhibit A, which shall herein be defined as
                 the "Suite 900 Space."  All of the terms and conditions of the
                 Lease applicable to the Premises shall apply to such Suite 900
                 Space, except as set forth below in this Article.

                          72.2.1  The Ninth Floor Space will be delivered to
                 Tenant in its "as is", "as built" condition and state of
<PAGE>
                 repair.  Any fixtures not removed by the prior tenant shall be
                 left in place and not removed by Landlord.  Tenant shall
                 perform all work (the "Suite 900 Tenant's Word") necessary to
                 prepare the Suite 900 Space (i) at Tenant's sole cost and (ii)
                 in accordance with the Tenant Design and Construction Process
                 set forth on Exhibit "C" to the Lease and otherwise in
                 accordance with all relevant provisions of the Lease.  To the
                 extent required by law, Landlord will comply with the
                 requirements of the ADA applicable to the Core Elements of
                 Centerpointe II which may arise because of the performance of
                 the Suite 900 Tenant's Work and Tenant shall comply with all
                 other ADA requirements respecting the Suite 900 Space,
                 including those requirements arising from the Suite 900
                 Tenant's Work.

                          72.2.2  For purposes of the Suite 900 Space, there
                 shall be no Concession Fund.

                          72.3  The term of the Lease shall commence as to the
                 Suite 900 Space on May 10, 1997 ("Suite 900 Space Lease
                 Commencement Date").  The Term of the Lease as to the Suite
                 900 Space shall expire on May 31, 2002.

                          72.4  Base Rent payable for the Suite 900 Space shall
                 be Nineteen and 50/100 Dollars ($19.50) per rentable square
                 foot, inclusive of Electricity Costs, and subject to
                 adjustment as described in Article 6.3.  Base Rent for the
                 Suite 900 Space shall be payable as provided in Section 6.1.1.
                 Tenant's obligation to pay Rent for the Suite 900 Space shall
                 commence on May 10, 1997.

                          72.5  After the Suite 900 Space Lease Commencement
                 Date, Tenant's Centerpointe II Proportionate Share shall be
                 increased by an amount equal to the percentage derived by
                 dividing the rentable square footage of the Suite 900 Space by
                 204,481.  Therefore, after the Suite 900 Space Lease
                 Commencement Date, Tenant's Counterpointe II Proportionate
                 Share shall equal 51.56%.

                          72.6  Except as modified by this Ninth Amendment, the
                 Lease shall otherwise remain in full force and effect.
<PAGE>
         IN WITNESS WHEREOF, and intending to be legally bound hereby, the
parties hereto have executed this Ninth Amendment to Lease as of the date first
set forth herein.

                                  LANDLORD:

                                  JOSHUA REALTY CORPORATION,
                                  a Delaware corporation

                                  By:  /s/    Dan Coughlan
                                       -------------------------------
                                       Name:
                                       Title:

                                  TENANT:

                                  AMERICAN MANAGEMENT SYSTEMS, INC.,
                                  a Delaware corporation

                                  By:  /s/    Frank A. Nicolai
                                       -------------------------------
                                       Name:  Frank A. Nicolai
                                       Title: Executive Vice President

[THE FOLLOWING PAGE INCLUDED AS AN EXHIBIT A FLOOR PLAN OF THE PREMISES.]
<PAGE>
                             TERMINATION AGREEMENT

         This TERMINATION AGREEMENT (this "Agreement"), made this 11th day of
February, 1997 between JOSHUA REALTY CORPORATION, a Delaware corporation
(general partner and sole remaining partner of Faircenter Limited Partnership,
a Delaware limited partnership) (the "Landlord"), and QUALITY SYSTEMS, INC., a
Virginia corporation (the "Tenant"), and VITRO CORPORATION, a Delaware
corporation (the "Guarantor").

                              W I T N E S S E T H:

         WHEREAS, by an Office Building Lease dated December 2, 1989, by and
between Landlord and Tenant (the "Lease"), Landlord leased to Tenant and Tenant
leased from Landlord all of that real property, situate and lying in Fairfax,
Virginia, which is described therein (the "Premises") (Capitalized terms used
herein and not otherwise defined shall have the meanings ascribed to them in
the Lease.); and

         WHEREAS, as of the date hereof, the Term of the Lease has not expired
or otherwise terminated, and the Lease remains in full force and effect; and

         WHEREAS, Landlord and Tenant desire to terminate the Lease, upon the
terms and subject to the conditions which are hereinafter set forth.

         NOW, THEREFORE, FOR AND IN CONSIDERATION of the mutual entry into this
Agreement by the parties hereto, and for other good and valuable consideration,
the receipt and adequacy of which are hereby acknowledged, the parties hereto
hereby agree as follows:

Section 1.  Termination of Lease.

         1.1.  Notwithstanding anything contained in the provisions of the
Lease to the contrary, the Term shall end at 11:59 o'clock p.m. on February 17,
1997 (the "Termination Date").  Tenant shall have no right to occupy or use the
Premises thereafter, and shall thereupon immediately surrender possession of
the Premises to Landlord in accordance with the provisions of Section 6.10 of
the Lease.

         1.2.  Termination of the Lease shall not alter or impair any and all
liability of Tenant or Guarantor accruing under the provisions of the Lease at
or before such termination of the Lease (including, by way of example rather
than of limitation, any
<PAGE>
liability for Base Annual Rent or Additional Rent accruing at or before such
termination).

Section 2.  Consideration.

         2.1     Consideration.  In consideration of the granting by Landlord
of the early termination of the Lease, Tenant shall pay to Landlord,
simultaneously with the execution of this Agreement, the amount of Twenty-Three
Thousand Eight Hundred Sixty-Nine and 32/100 Dollars ($23,869.32).

         2.2     Attorney's Fees.  Upon presentation of an invoice from
Landlord, Tenant agrees to reimburse Landlord for Landlord's attorney's fees
not to exceed $720.00 incurred in connection with both the termination of this
Lease and the Eighth Amendment to Lease Agreement between Landlord and American
Management Systems, Inc. of even date herewith.

         Section 3. Mutual release.  Provided that each party hereto performs
its obligations under the provisions of this Agreement and except as is
otherwise provided in subsection 1.2 hereof, each party hereto hereby releases
the other party from any and all obligations which the released party may have
to the other under the provisions of the Lease (including, by way of example
rather than of limitation, any and all such obligations which Tenant or
Guarantor may have for the payment of Rent to the Landlord which would have
been due beyond the Termination Date had this Lease not been terminated).

*not to exceed $720.00
<PAGE>
         IN WITNESS WHEREOF, each party hereto has caused this Agreement to be
and ensealed on its behalf by its duly authorized representatives, the day and
year first above written.

ATTEST/WITNESS:                   JOSHUA REALTY CORPORATION,
                                  a Delaware corporation

/s/ Raymond L. Owens              By:  /s/    Dan Coughlan
- ---------------------------            -------------------------------
                                       Name:  Daniel P. Coughland
                                       Title:

ATTEST/WITNESS:                   QUALITY SYSTEMS, INC.,
                                  a Virginia corporation

/s/ [SIG]                         By:  /s/    Dean O'Neill
- ---------------------------            -------------------------------
                                       Name:  Dean O'Neill
                                       Title: VP Finance & Admin.

ATTEST/WITNESS:                   VITRO CORPORATION

/s/ [SIG]                         By:  /s/    Arthur Rossi
- ---------------------------            -------------------------------
                                       Name:  Arthur Rossi
                                       Title: Senior Vice President<PAGE>
                                                                               .
                                                                               .
                                                                               .
                                                                   EXHIBIT 10.7

<TABLE>
<CAPTION>
                               TABLE OF CONTENTS

<S>                                                                      <C>
ARTICLE 1 BASIC LEASE INFORMATION AND CERTAIN DEFINITIONS....................1

ARTICLE 2 DEMISE; RENEWAL TERM AND TERM......................................3

      Section 2.01. Demise...................................................3
      Section 2.02. Renewal Terms............................................3
      Section 2.03. Definition of Term.......................................4

ARTICLE 3 DELIVERY OF THE PREMISES TO TENANT; RENTABLE AREA..................4

      Section 3.01. Delivery of the Premises to Tenant.......................4
      Section 3.02. Completion of the Premises...............................5
      Section 3.03. Rentable Area............................................5
      Section 3.04. Allowances Granted to Tenant.............................6

ARTICLE 4 ACCEPTANCE OF THE PREMISES AND BUILDING BY TENANT..................6

ARTICLE 5 BASE RENT..........................................................6

      Section 5.01. Base Rent - Initial Term.................................6
      Section 5.02. Base Rent - Renewal Term.................................7
      Section 5.03. Temporary Rent...........................................8
      Section 5.04. Payment..................................................8
      Section 5.05. Acceptance of Rent.......................................9
      Section 5.06. Survival of Rent Obligation..............................9
      Section 5.07. Default Interest.........................................9

ARTICLE 6 ADDITIONAL RENT....................................................9

      Section 6.01. Operating Expenses.......................................9
      Section 6.02. Real Estate Taxes.......................................15
      Section 6.03. Parking.................................................17
      Section 6.04. Additional Rent Defined.................................17
      Section 6.05. Rent Defined............................................17

ARTICLE 7 SERVICES BY LANDLORD..............................................17

      Section 7.01. Services Generally......................................17
      Section 7.02. Interruption in Services................................17

ARTICLE 8 UTILITIES.........................................................18

      Section 8.01. Computerized Energy Management System...................18
      Section 8.02. Water, Heating, Ventilating and Air Conditioning........19
      Section 8.03. Electricity.............................................19
      Section 8.04. Tenant's Security Regulations...........................20
      Section 8.05. Building Security System................................20

ARTICLE 9 USE...............................................................20
</TABLE>

                                       i
<PAGE>

<TABLE>
<S>                                                                      <C>
ARTICLE 10 COMPLIANCE WITH LAWS.............................................20

ARTICLE 11 OBSERVANCE OF BUILDING'S RULES AND REGULATIONS;
HAZARDOUS MATERIALS  .......................................................21

      Section 11.01. Rules and Regulations..................................21
      Section 11.02. Hazardous Materials....................................22

ARTICLE 12 ALTERATIONS......................................................23

      Section 12.01. Approval of Landlord...................................23
      Section 12.02. Ownership of Improvements to Premises..................24

ARTICLE 13 LIENS............................................................24

ARTICLE 14 REPAIRS..........................................................25

      Section 14.01. Tenant's Obligations...................................25
      Section 14.02. Landlord's Obligations.................................25

ARTICLE 15 INSURANCE........................................................26

      Section 15.01. Tenant's Insurance.....................................26
      Section 15.02. Insurance Rating.......................................27
      Section 15.03. Waiver of Subrogation..................................27
      Section 15.04. Landlord Insurance.....................................27
      Section 15.05. Self Insurance and Blanket Insurance...................28

ARTICLE 16 DAMAGE BY FIRE OR OTHER CASUALTY.................................28

      Section 16.01. Termination Rights Due to Damage or Destruction to the
                     Premises...............................................28
      Section 16.02. Damage to the Building.................................29
      Section 16.03. Partial Damage.........................................29
      Section 16.04. Damage During Last Year of Term........................29
      Section 16.05. No Landlord Liability..................................30
      Section 16.06. Apportionment of Rent..................................30

ARTICLE 17 CONDEMNATION.....................................................30

      Section 17.01. Entire Building........................................30
      Section 17.02. Partial Takings Affecting the Premises.................30
      Section 17.03. Termination of Lease...................................31
      Section 17.04. Landlord's Right to Award..............................31

ARTICLE 18 ASSIGNMENT AND SUBLETTING........................................31

      Section 18.01. Permitting Subletting of the Premises..................31
      Section 18.02. Rights of Tenant.......................................32
      Section 18.03. Required Provision in Sublease.........................33
      Section 18.04. Excess Rent............................................33
      Section 18.05. Rights of Landlord.....................................33
      Section 18.06. Permitted Occupants....................................34
</TABLE>

                                       ii

<PAGE>

<TABLE>
<S>                                                                      <C>
ARTICLE 19 INDEMNIFICATION..................................................34

ARTICLE 20 SURRENDER OF THE PREMISES........................................35

      Section 20.01. Condition of Premises..................................35
      Section 20.02. Tenant Holdover........................................35

ARTICLE 21 ESTOPPEL CERTIFICATES............................................35

ARTICLE 22 SUBORDINATION AND ATTORNMENT.....................................36

      Section 22.01. Existing Financings....................................36
      Section 22.02. Future Financings......................................36
      Section 22.03. Attornment.............................................37

ARTICLE 23 QUIET ENJOYMENT..................................................37

ARTICLE 24 SIGNS AND FURNISHINGS............................................37

      Section 24.01. Signs and Advertisements...............................37
      Section 24.02. Building Signage.......................................38
      Section 24.03. Furnishings............................................38
      Section 24.04. Satellite Dish.........................................39

ARTICLE 25 DEFAULTS AND REMEDIES............................................39

      Section 25.01. Events of Default......................................39
      Section 25.02. Remedies...............................................40
      Section 25.03. Remedies Cumulative....................................41
      Section 25.04. No Acceptance or Surrender.............................41
      Section 25.05. Customs and Practices..................................41
      Section 25.06. Payment of Tenant's Obligations by Landlord............41
      Section 25.07. Default by Landlord....................................42

ARTICLE 26 SECURITY DEPOSIT.................................................43

ARTICLE 27 INTENTIONALLY OMITTED............................................43

ARTICLE 28 ATTORNEY'S FEES AND LEGAL EXPENSES...............................43

ARTICLE 29 NOTICES..........................................................43

ARTICLE 30 RIGHT OF FIRST REFUSAL...........................................44

ARTICLE 31 MISCELLANEOUS....................................................45

      Section 31.01. No Partnership.........................................45
      Section 31.03. Severability...........................................46
      Section 31.04. Trial by Jury..........................................46
      Section 31.05. Force Majeure..........................................46
      Section 31.06. Captions...............................................46
</TABLE>

                                      iii

<PAGE>

<TABLE>
<S>                                                                      <C>
      Section 31.07. Benefit and Burden.....................................46
      Section 31.08. No Representations by Landlord.........................46
      Section 31.09. Entire Agreement.......................................46
</TABLE>

                                       iv

<PAGE>

                            OFFICE LEASE AGREEMENT

        THIS OFFICE LEASE AGREEMENT is made and entered into this 12th day of
August, 1993, by and between HYATT PLAZA LIMITED PARTNERSHIP, a Virginia limited
partnership ("Landlord") and AMERICAN MANAGEMENT SYSTEMS, INC., a Delaware
corporation ("Tenant"), upon all terms set forth in this Lease and in all
Exhibits hereto, to each and all of which terms Landlord and Tenant hereby
mutually agrees, and in consideration of One Dollar and other valuable
considerations, the receipt and sufficiency of which are hereby acknowledged,
and of the rents, agreements and benefits flowing between the parties hereto, as
follows:

                                  ARTICLE 1
               BASIC LEASE INFORMATION AND CERTAIN DEFINITIONS

        Section 1.01. Each reference to this Lease to information and
definitions contained in Article 1 and each use of the terms capitalized and
defined in this Section 1.01 shall be deemed to refer to, and shall have the
following meanings:

        A.      Building: Hyatt Plaza
                12701 Fair Lakes Circle
                Fairfax, Virginia 22033

        B.      Phase I Space: Refers to approximately 51,262 square feet of
                Rentable Area (defined in Section 3.03 of the Lease) located on
                the seventh (7th) and eighth (8th) floors of the Building, as
                more fully described and shown on Exhibit "A" - Part 1.

        C.      Phase II Space: Refers to approximately 32,974 square feet of
                Rentable Area located on the ninth (9th) and tenth (10th) floors
                of the Building, as more fully described and shown on Exhibit
                "A" - Part 2.

        D.      Phase I Rent Commencement Date: March 1, 1994, subject, however,
                to the provisions of Section 3.01(c) hereof.

        E.      Phase I Rent: Refers to an amount equal to the product obtained
                by multiplying $17.37 by the number of square feet of Rentable
                Area in the Phase I Space.

        F.      Phase II Rent Commencement Date: March 1, 1995, subject,
                however, to the provisions of Section 3.01(d) hereof.

        G.      Phase II Rent: Refers to an amount equal to the product obtained
                by multiplying $17.80 by the number of square feet of Rentable
                Area in the Phase II Space.

        H.      Initial Term: Ten (10) years.

        I.      Commencement Date: March 1, 1994.

<PAGE>

        J.      Expiration Date: February 29, 2004.

        K.      Rentable Area of the Building: 252,395 square feet.

        L.      Base Rent: Refers to the following:

                (i)     From the Phase I Rent Commencement Date to the Phase II
                        Commencement Date the Phase I Rent, any Temporary Rent
                        (defined in Section 5.03) and any Additional Space Rent
                        (defined in Article 30 hereof).

                (ii)    From the Phase II Rent Commencement Date to the
                        expiration of the Term an amount equal to the sum of (1)
                        the Phase I Rent; (2) the Phase II Rent; and (3) any
                        Additional Space Rent.

        M.      Base Year: Refers to the following:

                (i)     During the Initial Term: 1994.

                (ii)    During any Renewal Term: The base year or amount
                        established as part of the Market Rent (as defined in
                        Section 5.02 hereof).

        N.      Base Operating Expenses: The Operating Expenses (defined in
                Section 6.01(b)) incurred by Landlord during the Base Year.

        O.      Base Real Estate Taxes: The Real Estate Taxes (defined in
                Section 6.02(c)) assessed upon the Building during the Base
                Year.

        P.      Tenant's Proportionate Share: The result obtained by multiplying
                100% by a fraction, the numerator being the Rentable Area of the
                Premises and the denominator being the Rentable Area of the
                Building, provided that prior to the Phase II Rent Commencement
                Date the numerator shall be the Rentable Area of the Phase I
                Space only.

        Q.      Landlord's Address for Notices:

                c/o Hazel/Peterson Companies
                12500 Fair Lakes Circle
                Suite 400
                Fairfax, Virginia 22033
                Attention:  Asset Manager

                                      -2-
<PAGE>

        R.      Tenant's Address for Notices:

                4050 Legato Road
                Fairfax, Virginia 22030
                Attention:  Thomas W. Huba

        S.      Lease: Collectively refers to this Office Lease Agreement
                together with the following Exhibits which are attached hereto
                and incorporated herein by this reference.

<TABLE>
<CAPTION>
                  Exhibits

                  <S>        <C>
                  "A"        Floor Plans
                  "B"        Leasehold Improvements
                  "C"        Modified Method
                  "D"        Cleaning Specifications
                  "E"        HVAC Specifications
                  "F"        Barrier Removal Program
                  "G"        Rules and Regulations
                  "H"        Form Subordination Agreement
</TABLE>

        T.      Broker: Cushman & Wakefield of Virginia and Grubb & Ellis

        U.      Premises: Refers to the Rentable Area demised to Tenant by this
                Lease.

        V.      Fair Lakes: A mixed-use development in Fairfax County, Virginia.

                                  ARTICLE 2
                        DEMISE; RENEWAL TERM AND TERM

        Section 2.01. Demise. Landlord leases to Tenant, and Tenant leases from
Landlord, the Premises located in the Building for the Term (defined in Section
2.03) and subject to the provisions hereof. The Initial Term of this Lease shall
be for the period specified in Section 1.01 and shall begin at midnight on the
Commencement Date and shall, unless this Lease is sooner terminated in
accordance with the provisions of this Lease, end at midnight on the Expiration
Date, provided, however, that if for any reason the Expiration Date shall be a
day other than the final day of a calendar month then, the Term of this Lease
shall be extended so that it will expire on the last day of the calendar month
in which the Expiration Date takes place.

        Section 2.02. Renewal Terms. Tenant shall have the right to renew and
extend the Term of this Lease for two (2) Renewal Terms (herein so called) of
five (5) years each upon and subject to the following terms and conditions:

        (a)     Tenant may exercise its right to a Renewal Term by giving
written notice thereof to Landlord no later than thirty (30) days after its
receipt of the Market Rent Notice (as defined in Section 5.02 hereof) for the
Renewal Term in question. The Renewal Term shall commence immediately upon the
expiration of the Initial Term (as extended if Tenant had previously exer-

                                      -3-
<PAGE>

cised its right to the first Renewal Term) and upon such exercise the
"Expiration Date" of the Term shall automatically become the last day of the
current Renewal Term.

        (b)     The exercise by Tenant of its right to a Renewal Term must be
made, if at all, by written notice executed by Tenant and delivered to Landlord
on or before the date set forth hereinabove. Once Tenant has exercised its
option to a Renewal Term, the exercise may be revoked as more particularly
described in Section 5.02(b) hereof. Tenant shall not have the right to a
Renewal Term if Tenant is in Default (as defined in Section 25.01 hereof) under
this Lease, either at the time Tenant gives notice of its election, or
immediately prior to the commencement of a Renewal Term. If Tenant does not
exercise its right to a Renewal Term in a timely manner, then Tenant's rights
with respect thereto shall expire and be of no force or effect.

        Section 2.03. Definition of Term. As used in this Lease the word "Term"
collectively refers to the Initial Term, Renewal Term, if any, and, any
Temporary Occupancy Period (hereinafter defined).

                                  ARTICLE 3
              DELIVERY OF THE PREMISES TO TENANT; RENTABLE AREA

        Section 3.01. Delivery of the Premises to Tenant.

        (a)     Landlord shall deliver the Phase I Space and Phase II Space to
Tenant in its "as is" and "where as" condition with only the improvements
identified on Schedule 1 of Exhibit "B" hereto (the "Existing Improvements") on
or before December 5, 1993. For every day beyond December 5, 1993 that Landlord
has not delivered the Premises, the Rent Commencement Date for Phase I and Phase
II will be extended by one (1) day. The provisions of Exhibit "B" hereto shall
govern the construction and installation of all Leasehold Improvements (as
defined in Exhibit "B").

        (b)     It is acknowledged and agreed that Tenant (and its agents,
contractors and employees) may enter upon the Premises commencing after the date
it is delivered to Tenant pursuant to subparagraph (a) hereof to perform the
construction work required by this Lease to be performed by Tenant. Any entry
prior to the Commencement Date shall be subject to all of the terms and
conditions of this Lease, however, Tenant's obligations to pay Rent hereunder
shall commence on the Phase I Rent Commencement Date with respect to the Phase I
Space and on the Phase II Rent Commencement Date with respect to the Phase II
Space.

        (c)     The Phase I Rent Commencement Date shall occur on the earlier
of (i) March 1, 1994 or (ii) the date on which Tenant occupies any portion of
the Phase I Space for the operation of its normal business, provided, however,
that if Tenant occupies only a portion of the Phase I Space prior to March 1,
1994, then the Rent payable with respect to the Phase I Space for the period
from Tenant's occupancy for its normal business operations until March 1, 1994
shall be prorated so that Tenant shall pay Rent only with respect to the portion
of the Phase I Space Tenant is occupying for its normal business operations,
provided further, however, that Tenant shall commence paying Rent with respect
to all of the Phase I Space on March 1, 1994 whether or not Tenant has occupied
all of the Phase I Space. The period from Tenant's occupancy of any por-

                                      -4-
<PAGE>

tion of the Phase I Space for its normal business operations until March 1, 1994
is hereinafter referred to as the "Temporary Occupancy Period". The Tenant's
occupancy of any Phase I Space during the Temporary Occupancy Period will be
subject to the terms and conditions of this Lease and Tenant will be obligated
to pay Temporary Rent with respect to such space computed in accordance with
Section 5.03 hereof.

        (d)     The Phase II Rent Commencement date shall occur on the earlier
of (i) March 1, 1995 or (ii) the date on which Tenant occupies any portion of
the Phase II Space for the operation of its normal business, provided, however,
that if Tenant occupies only a portion of the Phase II Space prior to March 1,
1995, then the Rent payable with respect to the Phase II Space for the period
from Tenant's occupancy for its normal business operations until March 1, 1995
shall be prorated so that Tenant shall pay Rent only with respect to that
portion of the Phase II Space Tenant is occupying for its normal business
operations, provided, further, however, that Tenant shall commence paying Rent
with respect to all of the Phase II Space on March 1, 1995 whether or not Tenant
has occupied all of the Phase II Space. The period from Tenant's occupancy of
any portion of the Phase II Space for its normal business operations until March
1, 1995 is hereinafter referred to as the "Temporary Occupancy Period". Tenant's
occupancy of any Phase II Space during the Temporary Occupancy Period will be
subject to the terms and conditions of this Lease and Tenant will be obligated
to pay Temporary Rent computed in accordance with Section 5.03 hereof.

        (e)     Tenant shall indemnify Landlord and hold Landlord harmless from
and against any and all claims, damages, losses, liabilities, costs and expenses
(including without limitation attorneys' fees and court costs) which Landlord
may incur as a result of Tenant's entry on the Premises and construction of the
Leasehold Improvements to the Premises.

        Section 3.02. Completion of the Premises. Upon completion of a phase of
the Premises, Tenant will supply Landlord with (i) a certificate from the
Tenant's Architect (defined in Exhibit "B"), that, in its professional judgment,
the Leasehold Improvements to be constructed in the phase have been
substantially completed, and (2) copies of the non-residential use permit for
the phase.

        Section 3.03. Rentable Area. The term "Rentable Area" as used herein
means all the floor area in the Building and/or in the Premises and has been
calculated using a modified version of the standard method of measurements of
the Washington D.C. Association of Realtors (formerly the Washington Board of
Realtors) a copy of which is attached hereto as Exhibit "C" (the "Modified
Method"). The Rentable Area of each phase of the Premises is approximately
stated in Section 1.01 and shall be specifically calculated by Landlord's
architect using the Modified Method as Approved Plans (defined in Exhibit "B")
for a phase are completed. Upon such determination: (i) Landlord's architect
will send written certification of such determination to Landlord and Tenant
showing the method of calculation; (ii) such calculations shall be subject to
confirmation by Tenant's Architect and (iii) once the Rentable Area is agreed
upon the Rentable Area of the Premises and Base Rent specified in Section 1.01
shall be appropriately adjusted, if necessary, to reflect the agreed upon number
of square feet of Rentable Area of the Premises. The Rentable Area of the
Building and the Premises shall be adjusted, if necessary, by

                                      -5-
<PAGE>

Landlord's architect using the Modified Method in the event of any future
expansion or modification of the Premises. If the number of square feet of the
Rentable Area of the Premises changes, then Tenant's Proportionate Share shall
be adjusted effective as of the date of any such change.

        Section 3.04. Allowances Granted to Tenant. Landlord grants to Tenant an
allowance (the "Tenant's Allowance") equal to $10.00 per square foot of Rentable
Area in the original Premises. The Tenant Allowance will be disbursed pursuant
to the provisions of Exhibit "B". Any undisbursed or unused portion of the
Tenant Allowance may be used by Tenant to apply towards moving expenses or Rent
accruing hereunder at such time as all of the fees, costs and expenses
associated with work which Tenant is required to pay under this Lease have been
paid in full.

                                  ARTICLE 4
              ACCEPTANCE OF THE PREMISES AND BUILDING BY TENANT

        Taking possession of a phase of the Premises by Tenant shall be
conclusive evidence that Tenant: (i) accepts such phase as suitable for the
purposes for which they are leased; (ii) waives any defects in the phase of the
Premises. Except as specifically set forth in this Lease, and except for
negligence or willful misconduct of Landlord, its agents, employees, licensees
or servants, Landlord shall not be liable to Tenant or any of its agents,
employees, licensees, servants, or invitees for any injury or damage to person
or property due to (i) the condition or design of or any defect in the Premises
or its mechanical, plumbing and electrical systems and equipment which may exist
or occur, or (ii) any work performed by Tenant, its agents, employees,
licensees, servants, and invitees, and Tenant expressly assumes all risks for
injury or damage to person or property, either proximate or remote, resulting
from the condition of the Premises.

                                  ARTICLE 5
                                  BASE RENT

        Section 5.01. Base Rent - Initial Term. Commencing on the Rent
Commencement Date and continuing thereafter during the Initial Term of this
Lease Tenant shall pay to Landlord monthly, in lawful money of the United
States, without demand or offset (other than specifically permitted herein);
Base Rent as specified in Section 1.01 hereof. The Base Rent shall be paid in
equal monthly installments, each payable in advance, on or before the first day
of each calendar month during the Term. The monthly installment of Base Rent for
any partial calendar month of the Term shall be appropriately prorated.
(References to Base Rent in this Lease collectively refer to the Initial Term -
Base Rent and the Renewal Term - Base Rent determined in accordance with Section
5.02 hereof).

        Section 5.02. Base Rent - Renewal Term. In the event Tenant has
exercised an option for a Renewal Term of this Lease, then Tenant shall pay to
Landlord, during a Renewal Term, a Base Rent equal to ninety-five percent (95%)
of the then market rate being charged and/or granted to a tenant seeking a five
(5) year lease for a space of a size comparable to the Rentable Area of the
Premises, in a full service, first class office building located in the Fairfax
Center

                                      -6-
<PAGE>

area in buildings that are similar in age, quality of construction and
management of the Building (the "Market Rent"), multiplied by the number of
square feet of Rentable Area in the Premises. In determining Market Rent,
Landlord and Tenant shall also establish a new base (whether a year or an
amount) reflective of the market which will be used to determine the Base
Operating Expenses and Base Real Estate Taxes for the Renewal Term. All
determinations of Market Rent shall (i) reflect market conditions expected to
exist as of the date Base Rent based on Market Rent is to commence (including
base rents and escalations, rental abatements, construction allowances and other
tenant concessions, operating expense and tax passthrough provisions, and other
terms expected to be agreed to in market leases entered into at such time); (ii)
reflect the fact that Landlord is providing Tenant parking free of charge
pursuant to Section 6.03 hereof; and (iii) reflect any rent premiums that
buildings in Fair Lakes may receive. In determining the Market Rent, Landlord
and Tenant shall employ the following method and timetable to establish the
Market Rent.

        (a)     Not later than fourteen (14) months prior to the expiration date
of the Initial Term (or the first Renewal Term if Tenant had previously
exercised its option for a Renewal Term), Landlord shall deliver to Tenant
written notice (the "Market Rent Notice") of its proposed Market Rent for the
Premises during the applicable Renewal Term based on Landlord's determination of
the Market Rent. If Tenant (within the time period permitted by and in the
manner required by Section 2.02(a) hereof) elects to exercise its right to a
Renewal Term, Tenant shall also notify Landlord of Tenant's election to either
accept or reject the proposed Market Rent, set forth in the most recent Market
Rent Notice. Should Tenant accept the Market Rent proposed by Landlord in the
most recent Market Rent Notice, then such Market Rent will be used during the
applicable Renewal Term;

        (b)     Should Tenant reject the Market Rent set forth in the most
recent Market Rent Notice, Landlord and Tenant for _ period of thirty (30) days
will attempt to negotiate _ Market Rent. Should the parties reach an agreement,
then the agreed upon Market Rent shall be used during the applicable Renewal
Term. Should the parties fail to reach an agreement within such period, then,
Tenant, by written notice to Landlord given within ten (10) days after the
expiration of the foregoing thirty (30) day period, shall have the option to
either U) rescind its election for the Renewal Term, in which case, this Lease
shall terminate on the Expiration Date, or (ii) elect to use the appraiser
method described in subparagraph (c) hereof. An election by Tenant will be
irrevocable. A failure to notify Landlord within the ten (10) day period will be
deemed to be Tenant's election to rescind its election for the Renewal Term.

        (c)     In the event Tenant elects pursuant to subparagraph (b)(ii) to
invoke the appraiser method, Tenant in its notice to Landlord will select a
broker who has at least ten (10) years experience leasing commercial office
space in Fairfax County, Virginia (a "Broker"), to determine a Market Rent.

                (i)     Within ten (10) days after its receipt of the Tenant's
                        notice, Landlord shall engage a Broker and shall notify
                        the Tenant thereof. In the event Landlord does not
                        engage a Broker and provide Tenant notice as required
                        above,

                                      -7-
<PAGE>

                        then the Tenant's Broker shall select a Market
                        Rent which shall be deemed the Market Rent used during
                        the applicable Renewal Term.

                (ii)    Within five (5) days after the selection by Landlord
                        of a Broker, the two (2) Brokers shall (a) each
                        render their own determination of the Market Rent and
                        (b) choose a third Broker and notify Landlord and
                        Tenant of said choice. Each party shall bear the cost
                        of its appointed Broker and shall share equally the
                        cost of the third Broker. In the event that said two
                        (2) Brokers cannot agree on the choice of a third
                        Broker and they notify the parties thereof, then the
                        President of the Fairfax County Board of Realtors shall
                        choose a third Broker.

                (iii)   Within fifteen (15) days after the selection of the
                        third Broker, the third Broker shall, by
                        written notice, notify Landlord and Tenant of its
                        determination of Market Rent. The Market Rent for
                        purposes of this section shall equal the average of the
                        two closest determinations; provided, however, that (a)
                        if any one determination is agreed upon by any two of
                        the Brokers, then the Market Rent shall be such
                        determination, and (b) if any one determination is
                        equidistant from the other two determinations, then the
                        Market Rent shall be such middle determination.

        Section 5.03. Temporary Rent. During any Temporary Occupancy Period,
Tenant shall be obligated to pay to Landlord an adjusted rent (the "Temporary
Rent") for the Rentable Area occupied by Tenant computed in accordance with this
Section. For any Phase I Space occupied by Tenant during a Temporary Occupancy
Period, then Temporary Rent will be an amount equal to $7.00 per square foot of
Rentable Area occupied by Tenant. For any Phase II Space occupied by Tenant
during a Temporary Occupancy Period, the Temporary Rent will be $11.87 per
square foot of Rentable Area occupied by Tenant. The Temporary Rent shall be
paid in the same manner as Base Rent.

        Section 5.04. Payment. All Rent (as hereinafter defined) shall be paid
to Landlord by Tenant when due at Landlord's Address for Notices as specified in
Section 1.01, or such other place as Landlord may from time to time designate in
writing.

        Tenant shall only be required to pay Rent to one entity or person. In
the event more than one entity or person shall constitute Landlord hereunder,
they shall appoint by written notice to Tenant a single entity or person, (who
may be one of the entities or persons constituting Landlord), as (i) the
designated recipient of Rent; and (ii) the representative to whom Tenant should
direct all notices to Landlord and upon whose actions the Tenant may rely.
Tenant shall be entitled to pay Rent and rely upon the last named single
recipient until a new single recipient is named by written notice to Tenant.

        Section 5.05. Acceptance of Rent. If Landlord shall direct Tenant to pay
Rent to a lockbox or other depository whereby checks issued in payment of Rent
is initially cashed or deposited by a person or entity other than Landlord
(albeit on Landlord's authority), then, for any and all purposes under this
Lease: (i) Landlord shall not be deemed to have accepted such payment

                                      -8-
<PAGE>

until ten (10) days after the date on which Landlord shall have actually
received such funds, and (ii) Landlord shall be deemed to have accepted such
payment if (and only if) within said ten (10) day period, Landlord shall not
have refunded (or attempted to refund) such payment to Tenant. Nothing contained
in the immediately preceding sentence shall be construed to place Tenant in
default of Tenant's obligation to pay Rent if and for so long as Tenant shall
timely pay the Rent required pursuant to this Lease in the manner designated by
Landlord.

        Section 5.06. Survival of Rent Obligation. The obligation of Tenant with
respect to the payment of past due Rent shall survive the termination of this
Lease.

        Section 5.07. Default Interest. In the event any installment of Rent due
hereunder is not paid within five (5) calendar days after it is due, then such
delinquent installment of Rent or any component thereof shall bear interest from
the date originally due until paid, at the Default Rate (hereinafter defined in
Section 25.06 hereof). Notwithstanding the foregoing, Landlord agrees to waive
imposition of such interest with respect to the first late payment in any
calendar year.

                                  ARTICLE 6
                               ADDITIONAL RENT

        Section 6.01. Operating Expenses.

        (a)     Commencing on (i) January 1, 1995 with respect to the Phase I
Space and (ii) the Phase II Rent Commencement Date with respect to the Phase II
Space, and thereafter, throughout the Term, Tenant shall pay on a monthly basis,
without demand, as Additional Rent for the Premises, Tenant's Proportionate
Share of the amount by which Operating Expenses (as defined in Section 6.01(b)
hereof) exceed the Base Operating Expenses. Such payments shall be made as
follows:

        (i)     Commencing on January 1, 1995 and on the first day of January of
                each year during the remainder of the Term or as soon thereafter
                as is practicable, Landlord shall furnish Tenant with Landlord's
                reasonable estimate of the Operating Expenses for the year. On
                the first day of each month during such year, Tenant shall pay
                1/12th of Tenant's Proportionate Share of the difference between
                the estimated Operating Expenses for such year and the Base
                Operating Expenses. If for any reason Landlord has not provided
                Tenant with Landlord's Operating Expenses estimate on or before
                the first day of January of any year during the Term (or by the
                Commencement Date, as the case may be), then, until the first
                day of the calendar month following the month in which Tenant is
                given Landlord's estimate of Operating Expenses, Tenant shall
                continue to pay Landlord on the first day of each calendar month
                the monthly sum payable by Tenant under this Section 6.01 for
                the month of December of the preceding year.

        (ii)    On March 1, 1996 and thereafter on the first day of March of
                each year during the remainder of the Term, or as soon
                thereafter as reasonably practical, Landlord shall furnish to
                Tenant a statement of the actual Operating Expenses for the
                preceding year. Such statement shall provide Tenant with
                reasonable details regard-

                                      -9-
<PAGE>

                ing the various components of Operating Expenses. Within thirty
                (30) days after the delivery of that statement, Tenant shall
                either (i) notify Landlord, in writing, the Tenant objects to a
                component of the Operating Expenses on the grounds that it is
                not permitted by Section 6.01 hereof or (ii) pay to Landlord a
                lump sum payment equal to the amount, if any, by which Tenant's
                Proportionate Share of the actual Operating Expenses exceeds the
                amount, if any, which Tenant has paid toward the estimated
                operating Expenses pursuant to Section 6.01(a)(i) above or the
                undisputed amount thereof. Should Tenant dispute an Operating
                Expenses statement, (i) Tenant and Landlord shall in good faith
                attempt to resolve such dispute and (ii) in the event Landlord
                is unable to demonstrate by invoices or other supporting
                information the inclusion of an item or expenses as an Operating
                Expense, Landlord will not be permitted to charge or include
                such item. Within thirty (30) days after resolution of the
                dispute, Tenant will make a lump sum payment equal to the amount
                agreed upon by Landlord and Tenant. if Tenant's Proportionate
                Share of the actual operating Expenses is less than the amount
                Tenant has paid toward the estimated Operating Expenses pursuant
                to Section 6.01(a)(1) above, Landlord shall either (i) apply
                such amount to the next accruing installments of Rent due
                hereunder or (ii) if such excess arises after the Expiration
                Date, refund such amount to Tenant provided no Default by Tenant
                exists under Sections 25.01(a) and (b) hereof. The effect of
                this Section 6.01(a)(ii) is that Tenant will pay during each
                year during the Term Tenant's Proportionate Share of the actual
                operating Expense in excess of the Base Operating Expenses.

        (iii)   If the Term ends on a date other than the last day of December,
                the actual Operating Expenses for the year in which the
                Expiration Date occurs shall be prorated so that Tenant shall
                pay that portion of Tenant's Proportionate Share of Operating
                Expenses for such year represented by a fraction, the numerator
                of which shall be the number of days during such fractional year
                falling within the Term, and the denominator of which is 365 (or
                366, in the case of a leap year). The provisions of this Section
                6.01 shall survive the Expiration Date or any sooner termination
                provided for in this Lease.

        (iv)    Tenant shall have the right, during business hours and upon
                reasonable prior notice, one time during each calendar year to
                inspect Landlord's books and records relating to Operating
                Expenses, and/or to have such books and records audited at
                Tenant's expense by a certified public accountant mutually
                designated by Landlord and Tenant, except that any audit that
                discloses a discrepancy of more than three percent (3%) in the
                annual Operating Expenses and/or Real Estate Taxes shall be at
                Landlord's expense. Any discrepancy shall be promptly corrected
                by a payment of any shortfall to Landlord by Tenant within
                thirty (30) days after the applicable audit, or by a credit
                against the next payment(s) of rent hereunder, as may be
                applicable. In the event Tenant does not contest a statement of
                Operating Expenses within three hundred sixty-five (365) days
                after it is rendered, such statement shall become binding and
                conclusive; provided, however, that if a timely audit of
                Operating Expenses for a particular year reveals an error
                resulting

                                      -10-
<PAGE>

                in any overcharge with regard to particular expenses in such
                year, Tenant shall thereupon have the right to reexamine
                Landlord's books and records with respect to the immediately
                preceding two (2) calendar years for the sole purpose of
                determining whether the same error resulting in an overcharge
                with respect to the same expenses in such immediately preceding
                two (2) calendar years, and if so Tenant shall be entitled to a
                refund of such overcharged amount.

        (b)     As used in this Lease, "Operating Expenses" means all expenses,
costs, and disbursements of every kind which Landlord incurs, pays or becomes
obligated to pay in connection with the ownership, operation, repair, and
maintenance of the Building, which costs shall include all expenditures by
Landlord to maintain all facilities in operation at the beginning of the Term
and such additional facilities installed in subsequent years as Landlord may
consider necessary or beneficial for the operation of the Building. All
Operating Expenses shall be determined according to generally accepted
accounting principles (which shall be consistently applied) and shall include,
but are not limited to, the following:

        (i)     Wages, salaries, and fees of all personnel or entities
                (exclusive of Landlord's executive personnel) engaged in the
                operation, repair, maintenance, or security of the Building,
                including taxes, insurance, and benefits relating thereto (in
                the event the personnel service more than one building, expenses
                related to such person will be pro-rated to the Building on the
                basis of the amount of time the personnel spent servicing the
                Building);

        (ii)    All supplies and materials used in the operation, repair,
                security, and maintenance of the Building.

        (iii)   Cost of all maintenance and service agreements for the Building
                and the equipment therein, including, without limitation, alarm
                service, water treatment services, janitorial services, security
                systems service, window cleaning, service on electrical and
                mechanical components, trash removal, elevator maintenance,
                extermination service, plumbing service, grounds keeping, and
                landscaping;

        (iv)    Cost of all insurance relating to the Building for which
                Landlord is responsible hereunder (exclusive, however, of
                payments made by tenants of the Building pursuant to provisions
                in their lease similar to Section 15.02 hereof), or which
                Landlord considers reasonably necessary for the operation of the
                Building, including, without limitation, the cost of property,
                casualty and liability insurance applicable to the Building and
                Landlord's personal property used in connection therewith, and
                the cost of business interruption or rental insurance in such
                amounts as will reimburse Landlord for all losses of earnings
                and other income attributable to such perils as are commonly
                insured against by prudent landlords or required by Landlord's
                lender;

        (v)     Cost of repairs and maintenance (excluding repairs and
                maintenance paid by proceeds of insurance or by Tenant or other
                third parties or paid under guaranties, warranties or service
                contracts more particularly described in subparagraph (iii)

                                      -11-
<PAGE>

                hereof, and alterations attributable solely to tenants of the
                Building other than Tenant) of the Building;

        (vi)    All utility costs of the Building (exclusive, however, of such
                special utility services as are provided for in Article 8
                hereof, the costs of which special utility services shall be
                payable as therein provided), including, without limitation,
                water, power, fuel, heating, lighting, air-conditioning, and
                ventilating;

        (vii)   Amortization of the cost of installation of capital investment
                items which are installed primarily to reduce operating costs
                for the general benefit of the Building's tenants or to enhance
                the efficient operation of Building or which may be required in
                the future by any governmental authority, but which shall not
                include capital investment items required or generated by any
                specific tenant use. All such costs, including interest costs,
                shall be amortized over the reasonable life of the capital
                investment items, with reasonable life and amortization schedule
                being determined by Landlord according to generally accepted
                accounting principles, but in no event to extend beyond the
                reasonable life of the Building;

        (viii)  Landlord's central accounting costs, annual audits (except those
                costs and audits incurred for Landlord's sole benefit), and
                legal fees relating to the operation of the Building, but
                excluding legal fees relating to specific tenants;

        (ix)    A management fee to the manager of the Building, which fee shall
                not exceed the normal and customary management fees charged for
                managing comparable buildings in Fairfax County, Virginia.

        (x)     The Building's pro-rata share of office rent or rental value for
                any central Building management office located in another
                building located within Fair Lakes, provided that such rent or
                rental value shall not increase by more than two percent (2%) in
                any calendar year;

        (xi)    The Fair Lakes League Assessment, provided, however, that such
                assessment shall be included in Operating Expenses only if and
                to the extent that the item or service to which the assessment
                relates would be properly includible in Operating Expenses
                pursuant to this Section 6.01(b) if such item or service was
                provided or performed directly by Landlord; and

        (xii)   Costs to implement and maintain any controls on access to the
                Building parking lot which Landlord deems necessary pursuant to
                Section 6.03 hereof.

        (c)     Notwithstanding any other provision of this Lease, operating
Expenses (as defined in Section 6.01(b) above) shall not include; and Landlord
shall be solely liable for, the following expenses:

        (i)     Costs of a capital nature (other than those permitted by Section
                6.01(b)(7) above), including but not limited to, capital
                improvements, capital repairs; capital equip-

                                      -12-
<PAGE>

                ment and capital tools, all in accordance with generally
                accepted accounting principles;

        (ii)    Repairs or other work occasioned by insured casualty or by the
                exercise of eminent domain, to the extent Landlord is
                reimbursed by insurance maintained by Landlord or by Tenant or
                another tenant of the Building or by the condemning authority;

        (iii)   Leasing commissions, attorneys' fees, costs and disbursements
                and other expenses incurred in connection with negotiations or
                disputes with present or prospective tenants or other occupants
                of the Building;

        (iv)    Costs incurred in improving, decorating, building-out, painting
                or redecorating space for other tenants of the Building;

        (v)     Expenses in connection with services or other benefits of a type
                which are not provided Tenant but which are provided to another
                tenant of the Building;

        (vi)    Costs incurred due to violation by Landlord or any other tenant
                of the Building of the terms and conditions of any lease of
                space in the Building;

        (vii)   Interest or debt or amortization payments on any mortgage or
                mortgages;

        (viii)  Payments of rent by Landlord to any ground lessor;

        (ix)    Landlord's general overhead not related to the operation of the
                Building (but without limiting Landlord's right to seek
                reimbursement as provided in Sections 6.01(b)(i), (viii), (ix)
                and (x) above);

        (x)     Advertising and promotional expenditures with respect to the
                Building;

        (xi)    Any costs, fines or penalties incurred due to either (i)
                violations by Landlord of any governmental rule or authority or
                (ii) late payments by Landlord under any service, contract, lien
                or encumbrance applicable to the Building;

        (xii)   Wages, salaries or other compensation paid to any executive
                employees above the grade of building manager;

        (xiii)  Rentals and other related expenses incurred in leasing
                air-conditioning systems, elevators or other equipment
                ordinarily considered to be of capital nature;

        (xiv)   Any cost or expense whatsoever arising from or related to any
                clean-up of any Hazardous Materials (as defined in Section
                11.02(d)), or any governmental penalty of fines associated
                therewith, excepting, however, any such cost or expense
                resulting from the negligent or intentional acts of Tenant;

                                      -13-
<PAGE>

        (xv)    The cost of excessive use of Building utilities (such as HVAC or
                electricity) by other tenants of the Building, and/or utility
                service by other tenants outside normal Building hours, and/or
                utility service paid by tenants directly to utility companies
                based on separate metering;

        (xvi)   Any other cost or expense which would not be considered an
                operating expense under generally accepted accounting principles
                consistently applied;

        (xvii)  Costs incurred in connection with the sale, financing,
                refinancing, mortgaging or change of ownership of the Building
                or the Project, including without limitation, brokerage
                commissions, attorneys' and accountants' fees, closing costs,
                title insurance premiums, transfer taxes and interest charges;

        (xviii) Any and all loss, claim, damage, award or other amount paid or
                payable by Landlord (including all attorneys, fees, court costs
                and other costs incurred in connection therewith) as a result or
                arising out of any act of negligence, breach of contract or
                willful misconduct by the Landlord or its agents, employees or
                contractors to the extent not covered by insurance;

        (xix)   Bad debt losses, rent losses or reserves for such losses;

        (xx)    Non-cash items, such as deductions for depreciation and
                amortization of the Building and the Building equipment;

        (xxi)   Costs incurred in operating concessions such as (but not limited
                to) newspaper or cigarette stands;

        (xxii)  Any cost representing an amount paid for services or materials
                to a person, firm or entity related to Landlord or any general
                partner of Landlord to the extent such amount exceeds the amount
                that would be paid for such services or materials at the then
                existing market rates to an unrelated person, firm or
                corporation; and

        (xxiii) Any capital costs associated with phasing out chlorofluorocarbon
                refrigerants.

        (d)     If the average occupancy rate for the Building during any
calendar year (including the Base Year), is less than one hundred percent
(100%), or if any tenant is separately paying for utility or janitorial services
furnished to its premises which normally would be included in Operating Expenses
(as opposed to janitorial or utility services addressed in Section 6.01(c)(5)
and (15) and/or special utility services as are provided in Article 8 hereof),
then Operating Expenses for such calendar year shall be deemed to include all
additional expenses, as reasonably estimated by Landlord, which would have been
incurred during such calendar year if such average occupancy rate had been one
hundred percent (100%) and if Landlord paid for utility and janitorial services
furnished to such premises.

                                      -14-
<PAGE>

        Section 6.02. Real Estate Taxes.

        (a)     Commencing on (i) January 1, 1995 with respect to the Phase I
Space and (ii) the Phase II Rent Commencement Date with respect to the Phase II
Space, and continuing thereafter throughout the Term, Tenant shall pay on a
monthly basis, without demand, as Additional Rent for the Premises, Tenant's
Proportionate Share of the amount by which Real Estate Taxes (as defined in
Section 6.02(c) hereof) exceed the Base Real Estate Taxes. Such payments shall
be made as follows:

        (i)     Prior to January 1, 1995 and on the first day of January of each
                year during the remainder of the Term, or as soon thereafter as
                practicable, Landlord shall furnish Tenant with Landlord's
                reasonable estimate of the Real Estate Taxes for the forthcoming
                year. On the first day of each month during such year, Tenant
                shall pay 1/12th of Tenant's Proportionate Share of the
                difference, if any, between the estimated Real Estate Taxes for
                such year and the Base Real Estate Taxes. if for any reason
                Landlord has not provided Tenant with Landlord's estimate of
                Real Estate Taxes on or before the first day of January of any
                year during the Term, then until the first day of the calendar
                month following the month in which Tenant is given Landlord's
                estimate of Real Estate Taxes, Tenant shall continue to pay to
                Landlord on the first day each calendar month the monthly sum
                payable by Tenant under this Section 6.02 for the month of
                December of the preceding year.

        (ii)    Commencing on March 1, 1996 and thereafter on the first day of
                March of each year during the remainder of the Term, or as soon
                thereafter as reasonably practical, Landlord shall furnish to
                Tenant a statement of the actual Real Estate Taxes for the
                preceding year. Within thirty (30) days after the delivery of
                that statement, a lump sum payment will be made by Tenant equal
                to the amount, if any, by which Tenant's Proportionate Share of
                the actual Real Estate Taxes exceeds the amount, if any, which
                Tenant has paid toward the estimated Real Estate Taxes pursuant
                to Section 6.02(a)(i) above. If Tenant's Proportionate Share of
                such items is less than the amount Tenant has paid toward the
                estimated Real Estate Taxes pursuant to Section 6.02(a)(i)
                above, Landlord shall apply such amount to the next accruing
                installments of Rent due hereunder. The foregoing
                notwithstanding, Landlord shall have the right from time to time
                during any year, but not more frequently then twice during any
                calendar year, to notify Tenant in writing of any change in
                Landlord's estimate of Real Estate Taxes for the then current
                year, in which event Tenant's Proportionate Share of Real Estate
                Taxes, as previously estimated, shall be adjusted to reflect the
                amount shown in such notice and shall be effective, and due from
                Tenant, on the first day of each month following Landlord's
                giving of such notice. The effect of this Section 6.02(a) is
                that Tenant will pay during each year during the Term Tenant's
                Proportionate Share of the actual Real Estate Taxes in excess of
                the Base Real Estate Taxes.

        (b)     If the Term ends on a date other than the last day of December,
the actual Real Estate Taxes for the year in which the Expiration Date occurs
shall be prorated so that Tenant

                                      -15-
<PAGE>

shall pay that portion of Tenant's Proportionate Share of Real Estate Taxes for
such year represented by a fraction, the numerator of which shall be the number
of days during such fractional year falling within the Term, and the denominator
of which is 365 (or 366, in the case of a leap year). The provisions of this
Section 6.02 shall survive the Expiration Date or any sooner termination
provided for in this Lease.

        (c)     As used in this Lease, the term "Real Estate Taxes" shall
                include the following:

        (i)     All real estate taxes, including general and special
                assessments, if any, which are imposed upon Landlord or assessed
                against the Building or the land upon which the Building is
                situated;

        (ii)    Any other present or future taxes or governmental charges that
                are imposed upon Landlord, or assessed against the Building or
                the land upon which the Building is situated, including, but not
                limited to, any tax levied on or measured by the rents payable
                by tenants of the Building which is in the nature of, or in
                substitution for, real estate taxes. Any inheritance, estate,
                gift, franchise, corporation, income, or net profits tax which
                may be assessed against Landlord and/or the Building shall be
                excluded.

        (d)     Notwithstanding anything to the contrary contained in this
Section 6.02 during the Term of this tease, Landlord agrees to appeal and/or
seek other appropriate remedies in the event that Landlord determines, in its
reasonable discretion, that the Real Estate Taxes for the Building or land upon
which it is situated are excessive when compared to assessments or levies
imposed or levied upon other buildings of a similar size, age, condition and
occupancy level located in Fair Lakes. Should Landlord succeed in any challenge
to the assessment or levy, any reduction of the Real Estate Taxes, for periods
occurring during the Term, shall be passed on to the tenants in the Building by
way of a credit against or a reduction in the current year's Real Estate Taxes
used to determine Tenant's Proportionate Share of the same. Upon receiving a
notice of reassessment with respect to the Building and/or the land upon which
it is situated from Fairfax County, Landlord will furnish Tenant with a copy
thereof. Landlord shall make a determination whether or not to challenge or
appeal such reassessment based on Landlord's reasonable judgment of which course
is in the best interest of the Building. Landlord shall inform Tenant of such
determination, and shall make available appropriate personnel to discuss with
Tenant the reasons underlying such determination. In the event Landlord
initially determines not to challenge or appeal such reassessment, Landlord
agrees to consider in good faith any desire expressed by Tenant that such
reassessment be challenged or appealed; however, the final determination shall
be made by Landlord as provided above.

        Section 6.03. Parking. During the Term, Tenant and its employees,
invitees, and guests shall have the right to use, in common, with the other
tenants of the Building, free of charge, the parking areas of the Building, all
on an unassigned and unreserved basis. Landlord reserves the right to promulgate
reasonable rules and regulations of general application for the use of all
parking spaces. At all times during the Term, Tenant shall be entitled to use
3.2 parking spaces in the Building's parking lot for each 1,000 square feet of
Rentable Area in the Premises. In the

                                      -16-
<PAGE>

event excessive use of the parking lot by other tenants or visitors to the
Building results in a repeated unavailability of spaces for Tenant's use in the
foregoing ratio, Landlord shall implement such controls on access to and use of
the parking lot by other tenants and visitors as Landlord may deem necessary in
its reasonable discretion to prevent such excessive use.

        Section 6.04. Additional Rent Defined. The term "Additional Rent" shall
include, but not be limited to (i) the fees, if any, under Section 5.07; (ii)
Tenant's Proportionate Share of Operating Expenses as calculated under Section
6.01; (iii) Tenant's Proportionate Share of Real Estate Taxes as calculated
under Section 6.02; and (iv) all other costs and expenses which Tenant assumes,
agrees or is required to pay to Landlord pursuant to this Lease. In the event of
nonpayment of Additional Rent, Landlord shall have all the rights and remedies
herein provided for in case of nonpayment of Rent.

        Section 6.05. Rent Defined. The term "Rent" shall include Base Rent and
Additional Rent.

                                  ARTICLE 7
                             SERVICES BY LANDLORD

        Section 7.01. Services Generally. While Tenant or its Permitted
Occupants (defined in Section 18.06 of this Lease) are occupying the Premises,
Landlord shall furnish the Premises with: (i) passenger elevator service in
common with other tenants for access to and from the Premises, provided that
Landlord may reasonably limit the number of elevators to be operated at night
after normal business hours and on Saturdays, Sundays, and holidays so long as
at least one elevator is in service at all times and that Landlord may remove
elevators from service for maintenance; (ii) janitorial cleaning services Monday
through Friday (except "Holidays", which for purposes of the Lease are defined
as being New Year's Day, Lee Jackson King Day, Washington's Birthday, Memorial
Day, Independence Day, Labor Day, Thanksgiving Day, Friday after Thanksgiving
Day and Christmas Day) consistent with the cleaning specifications attached
hereto as Exhibit "D"; (iii) replacement, as necessary, of all fluorescent lamps
and ballasts in the Existing Improvements light fixtures within the Premises;
and (iv) the utility services provided for in Article 8 below. If Tenant
requires services which are not specified herein Tenant may, in writing, request
Landlord to provide such services. Should Landlord elect to provide such
additional services to Tenant, Tenant will pay to Landlord, upon demand, as
Additional Rent, Landlord's reasonable charges for providing such additional
services.

        Section 7.02. Interruption in Services. Failure to furnish, or any
stoppage of, the services provided for in this Article 7 and in Article 8 below
resulting from any cause will not make Landlord liable in any respect for
damages to any person, property, or business, nor be construed as an eviction of
Tenant, nor entitle Tenant to any damages because of malfunctions or any
interruptions in service. Notwithstanding the foregoing, if such malfunction or
interruption in service is due solely to the negligent act or willful omission
of Landlord or its agents, employees, contractors or representatives, and such
malfunction or interruption in service (i) continues for two (2) consecutive
business days and (ii) makes it reasonably impossible for Tenant to continue to
occupy, operate and/or use the Premises (or portion thereof), and (iii) requires
Tenant to discon-

                                      -17-
<PAGE>

tinue its occupancy, operations and/or use of the Premises (or portion thereof),
then, and only in such cases, Tenant shall be entitled to an abatement of the
Rent accruing from the time of the disruption, for the portion of the Permission
which Tenant has discontinued its use, operations and/or occupancy. The
abatement shall be for the period commencing on the date of the malfunction or
interruption of services, and continuing until the date such service is
corrected or restored. Notwithstanding the foregoing, if the service has not
been corrected and restored and Tenant recommences its use, operations and/or
occupancy of a portion of the Premises in which its use, operations and/or
occupancy were discontinued because of the interruption in service, then,
Tenant's right to abate Rent applicable to the portion of the Premises
reoccupied shall terminate. In addition to the foregoing, if such malfunction or
interruption in service is caused by anything other than the negligence or
willful acts or omissions of Tenant, and such malfunction or interruption
continues for five (5) consecutive business days then Tenant shall be entitled
to an abatement of Rent with respect to any portion of the Premises that is
rendered unusable by Tenant as described above and which is not occupied by
Tenant, for the period commencing on the date of the malfunction or interruption
of services and continuing until earlier of the date such service is corrected
or restored and the date Tenant reoccupies the vacated space, provided that in
the event of an abatement of Rent Tenant shall be obligated to assign and
deliver to Landlord all proceeds it receives as a result of (i) any business
interruption insurance maintained by Tenant with respect to the Premises or (ii)
any other insurance maintained by Tenant for which Tenant receives a
reimbursement as a result of the malfunction or interruption of services. If any
such malfunction or interruption in service (not caused by the negligence or
willful acts or omissions of Tenant) continues for sixty (60) consecutive days,
then Tenant shall have the right to terminate this Lease by written notice to
Landlord given prior to the date such service is corrected or restored.

                                  ARTICLE 8
                                  UTILITIES

        Section 8.01. Computerized Energy Management System. The Building has
been designed with a Computerized Energy Management System (the "CEMS") which
controls the heating, ventilating and air conditioning system (the "HVAC") and
electrical system for the Premises, Tenant will designate to Landlord authorized
representatives of the Tenant who will be given, through the CEMS, direct
control of the HVAC and lighting system for use after normal Building hours.

        Section 8.02. Water, Heating, Ventilating and Air Conditioning.

        (a)     While Tenant or its subtenants or assigns permitted by this
Lease are occupying the Premises under this Lease, Landlord shall furnish Tenant
with the following utilities in the manner and to the extent customarily
provided in office buildings in the Northern Virginia area: (1) potable water at
those points of supply provided periodically for normal lavatory use by tenants
in the Building; (2) heating, ventilating, and air-conditioning in season on
business days from 7:00 a.m. to 6:00 p.m., and on Saturdays from 8:00 a.m. to
1:00 p.m. (except Holidays) consistent with the HVAC specifications attached
hereto as Exhibit "E"; and (3) electric lighting

                                      -18-
<PAGE>

for public areas and special service areas of the Building. If Tenant requires
air-conditioning or heating outside the hours and days specified above, the
additional service may be requested by use of the CEMS and Tenant will pay for
such services based on measurement from the CEMS at the actual cost incurred by
Landlord therefor. The after-hours cost, as of the Commencement Date of this
Lease, shall be $40.00 per hour per floor which is subject thereafter to change
as actual costs increase.

        (b)     Except as set forth in Article 7 hereof, Landlord shall not be
liable for its failure to maintain comfortable atmospheric conditions in all or
any portion of the Premises due to heat generated by any equipment or machinery
installed by Tenant (with or without Landlord's consent) that exceeds generally
accepted engineering design practices for normal modern office purposes. If
Tenant desires additional cooling to offset excessive heat generated by such
equipment or machinery, Landlord will have the right to require Tenant to
install supplemental air conditioning units in the Premises, and the full cost
thereof, including the cost of installation of unit(s) and meter(s), operation,
use, and maintenance will be paid by Tenant.

        Section 8.03. Electricity.

        (a)     While Tenant or its subtenants or assigns permitted by this
Lease are occupying the Premises, Landlord will furnish sufficient power for
lighting and for typewriters, word processors, calculating machines, copying
machines, personal computers and other modern office equipment. Tenant will not
install or operate in the Premises any heavy duty electrical equipment or
machinery without first obtaining prior written consent of Landlord, which
consent shall not be unreasonably withheld or delayed. Landlord may require, as
a condition of its consent, for the installation of such equipment or machinery,
payment by Tenant as additional rent for excess consumption of electricity that
may be occasioned by the operation of said equipment or machinery. Landlord may
make periodic inspections of the Premises at reasonable times to determine that
Tenant's electrically operated equipment and machinery complies with the
provisions of this Article 8.

        (b)     If the measurements from the CEMS reveals Tenant's use of
electricity in the Premises exceeds a reasonable level of consumption for a
modern business office, then Tenant agrees to pay Landlord (or the utility
company if direct service is provided by such company) promptly upon demand
therefor, for all such excessive electric consumption and demand as shown by the
CEMS at the rates charged for such service by the local public utility company.
For Tenant's information, provisions similar to this subparagraph are and will
be contained in all leases for the Building.

        Section 8.04. Tenant's Security Regulations. It is acknowledged that
Tenant's use of the Premises may require security systems in addition to those
provided pursuant to Section 8.05. Tenant shall have the right, at its sole cost
and expense, to install in the Premises additional locks or other security
access systems. Upon the Expiration Date, Tenant shall remove such additional
locks and security systems and restore the affected portions of the Premises as
required by this Lease.

                                      -19-
<PAGE>

        Landlord agrees that, notwithstanding anything to the contrary contained
in this Lease, except in emergency situations, Landlord's access to the Premises
will be upon reasonable prior notice to Tenant and subject to Tenant's rules and
regulations related to security. Landlord and Tenant agree to cooperate with
each other so as to establish a mutually acceptable system so as to permit
Landlord to provide janitorial and other services to the Premises in a manner
consistent with Tenant's security concerns.

        Section 8.05. Building Security System. The Building has been
constructed with a card access computerized security system which limits access
to the Building after normal Building hours. Tenant will designate in writing to
Landlord those employees of the Tenant who will be given access to the Building
after hours. Landlord will have no liability to Tenant in the event of any loss
or damage to the Premises resulting from the entry by Tenant's employees into
the Premises and/or Building after normal Building hours.

                                  ARTICLE 9
                                     USE

        The Premises shall be used solely for general office purposes and for no
other purpose. Tenant agrees to use and maintain the Premises in a clean,
careful, safe, lawful, and proper manner.

                                  ARTICLE 10
                             COMPLIANCE WITH LAWS

        (a)     Except as set forth in subparagraph (b) of this Article or
otherwise to the contrary contained in this Lease, Tenant shall, at its sole
expense, promptly and faithfully (i) comply with all present and future laws,
ordinance, orders, rules, regulations, and requirements of every governmental
authority having jurisdiction over the Premises (including, but not limiting
the generality of the foregoing Americans with Disabilities Act 42 USC Section
12101 et seq. (the "ADA")) to the extent applicable to the Premises or Tenant's
particular use of the Premises; (ii) comply with any direction made pursuant to
law by any public officers which requires abatement of any nuisance or imposes
upon Landlord or Tenant any duty or obligation arising from Tenant's occupancy
or use of the Premises or from conditions which have been created by or at the
insistence of Tenant, (iii) comply with the requirements of the local board of
fire underwriters, or any body exercising similar functions with respect to the
construction, care and safety, maintenance and operation of the Premises to the
extent applicable to the Premises or Tenant's use of the Premises; and (iv)
indemnify Landlord and hold Landlord harmless from any loss, cost, claim, or
expense which Landlord may incur or suffer by reason of Tenant's failure to
comply with its obligations under clauses (ii), or (iii) above, so long as such
failure is not due to (i) the acts or omission or negligence of Landlord or its
employees, agents, contractors, servants and licensees or (ii) a default by
Landlord hereunder.

        (b)     Except as set forth in subparagraph (a) of this Article or
otherwise assumed by Tenant pursuant to this Lease, Landlord shall promptly and
faithfully (i) comply with all present and future laws, ordinances, orders,
rules, regulations and requirements of every governmental

                                      -20-
<PAGE>

authority having jurisdiction over the Building (including, but not limiting the
generality of the foregoing, the items maintained by Landlord pursuant to
Section 14.02 hereof); (ii) comply with any direction made pursuant to law by
and public officers which require abatement of any nuisance which imposes upon
Landlord or Tenant any duty or obligation arising from Landlord's operation or
maintenance of the Building or from conditions which have been created by or at
the insistence of Landlord; (iii) comply with the requirements of the local
board of fire underwriters, or any body exercising similar functions with
respect to the construction, care and safety, maintenance and operation for the
Building; and (iv) indemnify Tenant and hold Tenant harmless from any loss,
cost, claim, or expense which Tenant may incur or suffer by reason of Landlord's
failure to comply with its obligations under clauses (i), (ii), or (iii) above,
so long as such failure is not due to (i) the acts or omissions or negligence of
Tenant or its employees, agents, contractors, servants and licensees; or (ii) a
Default by Tenant hereunder.

        (c)     Landlord represents that as of the date hereof and as of the
Commencement Date, the Building complies with all applicable laws, ordinances,
orders, rules and regulations and requirements of every governmental authority
having jurisdiction over the Building, except as it pertains to the ADA.
Landlord, as of the date of this Lease, is currently implementing a program to
remove barriers in the common areas of the Building as required by the ADA and
shall complete the same at its sole cost and expense. A copy of Landlord's
barrier removal program is attached as Exhibit "F".

        (d)     If either party receives notice of any such direction or of
violation of any such law, order, ordinance, or regulation, the party receiving
such notice shall promptly notify the other thereof.

                                  ARTICLE 11
                        OBSERVANCE OF BUILDING'S RULES
                     AND REGULATIONS; HAZARDOUS MATERIALS

        Section 11.01. Rules and Regulations. Tenant and its servants,
employees, agents, visitors, and licensees shall observe faithfully and comply
strictly with the Rules and Regulations attached to this Lease as Exhibit "G".
Landlord shall at all times have the right to make reasonable changes in and
additions to such Rules and Regulations; provided such changes in existing or
new rules and regulations do not materially interfere with the lawful conduct of
Tenant's business in the Premises. Any failure by Landlord to enforce any of the
Rules and Regulations now or hereafter in effect, either against Tenant or any
other tenant in the Building, shall not constitute a waiver of any such Rules
and Regulations. Landlord shall not be liable to Tenant for the failure or
refusal by any other tenant, guest, invitee, visitor, or occupant of the
Building to comply with any of the Rules and Regulations. Landlord shall,
however, enforce the Rules and Regulations in a nondiscriminatory manner in what
Landlord reasonably determines, in its reasonable discretion, to be in the best
interests of the Building and its tenants. If there is any inconsistency between
this Lease and the Rules and Regulations set forth in Exhibit "G" hereto, this
Lease shall govern.

                                      -21-
<PAGE>

        Section 11.02. Hazardous Materials.

        (a)     Except for those materials that are necessary in the normal
course of Tenant's business activities associated with the use of the Premises
permitted by this Lease, Tenant, its agents, employees, contractors or invites
shall not (i) cause or permit any Hazardous Materials (hereinafter defined) to
be brought upon, stored, used or disposed on, in or about the Premises and/or
the Building, or (ii) permit the release, discharge, spill or emission of any
substance considered to be a Hazardous Material from the Premises.

        (b)     Any Hazardous Materials permitted by subparagraph (a), all
containers therefor, and all materials that have been contaminated by Hazardous
Materials shall be used, kept, stored and disposed of by Tenant in a manner that
shall in all respects comply with all applicable federal, state and local laws,
ordinances, regulations and standards.

        (c)     Tenant hereby agrees that it is and shall be fully responsible
for all costs, expenses, damages or liabilities (including, but not limited to
those incurred by Landlord and/or its mortgagee) which may occur from the use,
storage, disposal, release, spill, discharge or emissions of Hazardous Materials
by Tenant whether or not the same may be permitted by this Lease. Tenant shall
defend, indemnify and hold harmless Landlord, its mortgagee and its agents from
and against any claims, demands, administrative orders, judicial orders,
penalties, fines, liabilities, settlements, damages, costs or expenses
(including, without limitation, reasonable attorney and consultant fees, court
costs and litigation expenses) of whatever kind or nature, known or unknown,
contingent or otherwise, arising out of or in any way related to the use,
storage, disposal, release, discharge, spill or emission of any Hazardous
Material by Tenant, its agents, employees, contractors or invites. The
provisions of this Section shall be in addition to any other obligations and
liabilities Tenant may have to Landlord at law or in equity and shall survive
the transactions contemplated herein or any termination of this Lease.

        (d)     As used in this Lease, the term "Hazardous Materials" shall
include, without limitation:

        (i)     Those substances included within the definitions of "hazardous
                substances", "hazardous materials," toxic substances," or "solid
                waste" in the Comprehensive Environmental Response Compensation
                and Liability Act of 1980 (42 U.S.C. Section 9601 et seq.), as
                amended by Superfund Amendments and Reauthorization Act of 1986,
                the Resource Conservation and Recovery Act of 1976, and the
                Hazardous Materials Transportation Act, and in the regulations
                promulgated pursuant to said laws, all as amended;

        (ii)    Those substances listed in the United States Department of
                Transportation Table (49 CFR 172.101 and amendments thereto) or
                by the Environmental Protection Agency (of any successor agency)
                as hazardous substances (40 CFR Part 302 and amendments
                thereto);

        (iii)   Any material, waste or substance which is (A) petroleum, (B)
                asbestos, (C) polychorinated biphenyls, (D) designated as a
                "hazardous substance" pursuant to Sec-

                                      -22-
<PAGE>

                tion 311 of the Clean Water Act, 33 U.S.C. Section 1251 et seq.
                (33 U.S.C. Section 1321) or listed pursuant to Section of the
                Clean Water Act (33 U.S.CD. Section 1317); (E) flammable
                explosives; or (F) radioactive materials;

        (iv)    Those substances regulated pursuant to or identified in the
                Virginia Pesticide Law; Air Pollution Control Board; Virginia
                Waste Management Act; Environmental Health Service;
                Transportation of Hazardous Radioactive Materials; Virginia
                Hazardous Materials Emergency Response Program; State Water
                Control Law; The Groundwater Act of 1973; and Miscellaneous
                Offenses; and in the regulations promulgated pursuant to said
                laws, all as amended; and

        (v)     Such other substances, materials and wastes which are or become
                regulated as hazardous or toxic under applicable local, state or
                federal law, or the United States government, or which are
                classified as hazardous or toxic under federal, state, or local
                laws or regulations.

        (e)     Landlord represents and warrants that as of the date of this
Lease it has not received any notice that there are Hazardous Materials in the
Building; or that the Building violates any applicable law pertaining to
Hazardous Materials.

                                  ARTICLE 12
                                 ALTERATIONS

        Section 12.01. Approval of Landlord. After the initial Leasehold
Improvements are completed, Tenant shall not, at any time during the Term,
without Landlord's prior written consent, make any Alterations (hereinafter
defined) to the Premises. Should Tenant desire any Alterations, Tenant agrees to
submit all plans and specifications for same to Landlord for Landlord's written
approval, before beginning such work and Landlord's approval shall not be
unreasonably withheld, conditioned or delayed. Provided Tenant has supplied
Landlord with information and plans for the Alterations which reasonably details
the nature and scope of the same, Landlord's failure to respond to Tenant's
request for approval within ten (10) business days after receipt of the
information, plans and request for approval, shall be deemed to be Landlord's
approval of the same. Landlord shall not be considered as unreasonably
withholding its approval by refusing to consent to any Alterations which alter
the exterior appearance of the Building, or the public lobbies, corridors, or
common areas thereof; which will or are likely to cause any weakening of any
part of the structure of the Premises or Building or which may cause damage or
disruption to any Building system and such damage or disruption is not repaired
as part of the Alterations. Upon Tenant's receipt of Landlord's written
approval, Tenant may proceed with the construction of the approved Alterations,
but only so long as they are in substantial compliance with the plans any
specifications approved by Landlord and provisions of this Article 12.
Additionally, the construction of any alterations, (regardless of whether or not
Landlord's prior approval of the work is required by this Lease) the alterations
themselves, or any maintenance thereof shall comply with all building, safety,
fire, plumbing, electrical and other codes and governmental and insurance
requirements, and shall not require an amount of water, electricity, gas, heat,
ventilation, or air-conditioning which exceeds reasonable level of consumption
for a mod-

                                      -23-
<PAGE>

ern business office unless prior written arrangements reasonably satisfactory to
Landlord are made with respect thereto. All alterations shall be made at
Tenant's expense, either by Tenant's contractors which have been approved in
advance by Landlord or, at Tenant's option, by Landlord's contractors on terms
reasonably satisfactory to Tenant. In the event Landlord actually constructs the
alterations or is retained by Tenant to supervise or manage the construction by
contractors selected by Tenant and approved by Landlord, then Tenant shall pay
to Landlord a fee equal to ten percent (10k) of the actual costs of such work,
such fee to cover Landlord's overhead related to the work, including, but not
limited to, Landlord's review of the plans and specifications, coordination of
the work, consultation with professionals regarding the work, and general
administration allocable to the work. The foregoing fee will not be charged in
circumstances where Landlord has merely approved the Alterations. All such
construction shall be completed promptly and in a good and workmanlike manner
and shall be performed in compliance with Article 13 hereof.

        As used in this Lease, the term Alterations refers to work performed
after the completion of the initial Leasehold Improvements which would
reasonably be considered major construction, renovations or changes to the
Premises, having a material impact on the appearance of the Premises to other
portions of the Building, or would otherwise have a material impact (structural,
mechanical, operational or otherwise) upon the Building, and/or the total cost
of the construction renovations or changes is more than $75,000.00. Alterations
do not include, by way of example, the hanging of pictures, the movement of
furniture and flexible space walls or partitions, or the painting of the
interior of the Premises. Prior to commencing any alterations, Tenant will
coordinate with Landlord so as to schedule the movement of men, material and
equipment through the Building's common areas in a manner which does not
unreasonably interrupt the normal Building operations and the use and enjoyment
of the Building by other tenants therein.

        Section 12.02. Ownership of Improvements to Premises. All Existing
Improvements and improvements to the Premises constructed by Tenant and paid for
by Tenant from funds supplied by Landlord either in the form of allowances or
credits shall be and remain the Landlord's property, and shall not be removed
from the Premises. Tenant shall have the right, upon expiration of the Term, to
remove, at Tenant's expense, all alterations to the Premises (other than the
Existing Improvements and the improvements or alterations paid by allowances
granted by Landlord); specialized trade fixtures or other systems or items
installed by Tenant pursuant to Article 12 hereof, and; movable trade fixtures.
Tenant agrees to remove, at Tenant's expense all of its furnishings, furniture
and movable personal property by the Expiration Date. Tenant will promptly
restore any damage to the Premises or Building caused by its removal of its
property.

                                  ARTICLE 13
                                    LIENS

        Tenant shall promptly pay when due the entire cost of any work done on
the Premises by Tenant, its agents, employees, or independent contractors.
Tenant shall keep the Premises and the Building free from any liens arising from
any work performed, materials furnished, or obligations incurred by or at the
request of Tenant, its agents, employees or independent contractors. if any lien
is filed against the Premises, the Building or Tenant's leasehold interest
therein, which

                                      -24-
<PAGE>

arises out of any purported act or agreement of Tenant, Tenant shall discharge
same within thirty (30) days after its filing by either paying off the same or
depositing with a title company acceptable to Landlord (in its reasonable
discretion) such bond or other undertaking sufficient to stay any action to
foreclose the lien. If Tenant fails to discharge such lien or post a bond
securing the payment and discharge of the lien within such period, then, in
addition to any other right or remedy of Landlord, Landlord may, at its
election, discharge the lien by paying the amount claimed to be due, or by
depositing with a court or a title company, or by bonding, the amount claimed to
be due. Tenant shall pay on demand, as Additional Rent, any amount paid by
Landlord for the discharge or satisfaction of any such lien, and all attorney's
fees and other costs and expenses of Landlord reasonably incurred in defending
any such action or in obtaining the discharge of such lien, together with all
necessary disbursements in connection therewith. In the event Tenant posts a
bond to secure payment of a lien, such action does not relieve Tenant of its
obligation to discharge the lien prior to its foreclosure. Further, Landlord
reserves the right to draw upon any bond posted by Tenant to pay any lien if
Landlord, in its reasonable discretion, determines it is necessary to discharge
the same.

                                  ARTICLE 14
                                   REPAIRS

        Section 14.01. Tenant's Obligations. Tenant shall keep the Premises and
every part thereof in good condition and repair at all times during the Term and
at Tenant's sole cost and expense, normal wear and tear excepted. At the end of
the Term, Tenant shall surrender to Landlord the Premises and all alterations,
additions, and improvements thereto in the same condition as when received,
subject to the provisions of Section 12.02 and Article 20 hereof. Landlord shall
give Tenant five (8) business days notice to commence to make repairs. If Tenant
fails to commence to make such repairs within such time period, Landlord, at its
option, may make such repairs, and Tenant shall pay Landlord on demand
Landlord's actual costs in making such repairs plus a fee of ten percent (10W)
to cover Landlord's overhead, all to constitute Additional Rent. Landlord has no
obligation and has made no promise to alter, remodel, improve, repair, decorate,
or paint the Premises or any part thereof, except as specifically set forth in
this Lease. No representations respecting the condition of the Premises or the
Building have been made by Landlord to Tenant except as specifically herein set
forth.

        Section 14.02. Landlord's Obligations. Subject to the other provisions
of this Lease imposing obligations in this respect upon Tenant, and subject to
the provisions of Articles 16 and 17 hereof, Landlord shall, at its sole cost
and expense (but, subject, where applicable, to inclusion as part of the
Operating Expenses), repair, replace, and maintain:

        (i)     All common areas of the Building, including without limitation,
                the sidewalks, driveways, service areas and parking areas;

        (ii)    The exterior and structure of the Building and the Premises,
                including without limitation, the roof (including flashings and
                water tightness of the Building), walls (including caulking),
                floors and foundations and the landscaping for the Building;

                                      -25-
<PAGE>

        (iii)   The Building systems, including without limitation, heating,
                ventilating, air conditioning and sprinkler systems; and

        (iv)    The Building water, sewerage, gas, electrical, life safety
                systems, plumbing systems and other lines, pipes and conduits
                within the Building and the Premises.

                                  ARTICLE 15
                                  INSURANCE

        Section 15.01. Tenant's Insurance. Tenant, at its sole expense, shall
obtain and keep in force the, following insurance:

        (a)     Comprehensive public liability insurance coverage on an
"occurrence basis" against claims for personal injury, including, without
limitation, bodily injury, death, and broad form property damage, in limits not
less than $5,000,000 inclusive. All such insurance policies shall name Tenant as
the named insured thereunder and shall name Landlord and Landlord's mortgagees
as additional insureds thereunder, all as their respective interests may appear.

        (b)     Worker's Compensation and Employer's Liability insurance, with a
waiver of subrogation endorsement, in form and amount satisfactory to Landlord.

        (c)     All Risk Insurance insuring all personal property of Tenant (its
agents, employees, contractors, subtenants and permittees) located in the
Premises, including furniture, equipment fittings, installations, supplies and
any other personal property and Alterations ("Tenant's Property"), in an amount
equal to the full replacement value, it being understood that no lack or
inadequacy of insurance by Tenant shall in any event make Landlord subject to
any claim by virtue of any theft or loss or damage to any uninsured or
inadequately insured property; and

        (d)     During the course of construction of work, should any work be
performed by Tenant pursuant to Exhibit "B" or for any alterations by Tenant
until completion thereof: Builder's Risk Insurance on an "all risk" basis
(including collapse) on a completed value (nonreporting) form for full
replacement value covering all work incorporated in the Building and all
materials and equipment in or about the Premises.

        All policies shall be issued by companies having a Best's rating of at
least A:XII and shall be in amounts and in form satisfactory from time to time
to Landlord and Landlord's mortgagees. All policies shall contain an endorsement
or agreement by the insurer that, as to Landlord's interest, any loss shall be
payable in accordance with the terms of such policy notwithstanding any act or
negligence of Tenant which might otherwise result in forfeiture of said
insurance. Tenant will deliver certificates of insurance evidencing each policy
to Landlord as soon as practicable after the placing of the required insurance,
but not later than ten (10) days prior to the date Tenant takes possession of
all or any part of the Premises. All policies shall contain an undertaking by
the insurers to notify Landlord and Landlord's mortgagees in writing, by
Registered or Certified U.S. Mail, return receipt requested, not less than
thirty (30) days before any material change., reduction in the scope or limits
of coverage, cancellation, or other termination thereof.

                                      -26-
<PAGE>

        Landlord reserves the right, not more often than once every year, to
periodically review the insurance coverages required by this Section 15.01 and
to revise such requirements to reflect insurance industry practices or require
other forms or amounts of insurance as may be reasonably required to reflect
changes in insurance industry practices.

        Section 15.02. Insurance Rating. Tenant will not keep, use, sell, or
offer for sale in, or upon, the Premises any article which may be prohibited by
any insurance policy periodically in force covering the building and the
Leasehold Improvements. If Tenant's occupancy or business in, or on, the
Premises, whether or not Landlord has consented to the same, results in any
increase in premiums for the insurance periodically carried by Landlord with
respect to the Building or the Leasehold Improvements, Tenant shall pay any such
increase in premiums as Additional Rent within ten (10) days after being billed
therefor by Landlord.

        If any of Landlord's insurance policies shall be canceled or
cancellation shall be threatened or the coverage thereunder reduced or
threatened to be reduced in any way because of the use of the Premises or any
part thereof by Tenant or any assignee or sub-tenant of Tenant or by anyone
Tenant permits on the Premises and, if Tenant fails to remedy the condition
giving rise to such cancellation, threatened cancellation, reduction of
coverage, or threatened reduction of coverage within 48 hours after notice
thereof, Landlord may enter upon the Premises and attempt to remedy such
condition, and Tenant shall promptly pay the cost thereof to Landlord as
Additional Rent. Landlord shall not be liable for any damage or injury caused to
any property of Tenant or of others located on the Premises resulting from such
entry. If Landlord is unable or elects not to remedy such condition, then
Landlord shall have all of the remedies provided for in this Lease in the event
of a Default by Tenant. Notwithstanding the foregoing provisions of this
Section, if Tenant fails to remedy as aforesaid, Tenant shall be in Default of
its obligations hereunder and Landlord shall have no obligation to remedy such
Default.

        Section 15.03. Waiver of Subrogation. All policies covering real or
personal property which either party obtains affecting the Premises shall
include a clause or endorsement denying the insurer any rights of subrogation
against the other party to the extent rights have been waived by the insured
before the occurrence of injury or loss, if same are obtainable. Landlord and
Tenant waive any rights of recovery against the other for injury or loss due to
hazards covered by policies of insurance containing such a waiver or subrogation
clause or endorsement to the extent of the injury or loss covered thereby.

        Section 15.04. Landlord Insurance. Landlord, as part of the Operating
Expenses, shall obtain and keep in force the following insurance:

        (a)     Comprehensive public liability insurance coverage on an
"occurrence basis" against claims in or about the Building (other than the
Premises) for personal injury, including without limitation, bodily injury,
death and broad form property damage, in limits not less than $5,000,000
inclusive;

        (b)     Workmen's Compensation and Employer's Liability Insurance;

                                      -27-
<PAGE>

        (c)     All Risk Insurance insuring the Landlord's interest in the
Building, all Leasehold Improvements in the Premises constructed by Tenant using
funds supplied by Landlord (specifically excluding, Tenant's personal property
and all improvements in the Premises erected by Tenant using its own funds which
under Virginia law are considered fixtures (the "Fixtures")) in a form
satisfactory to Landlord and in an amount equal to the full replacement value of
the Landlord's insurable interest in the Building; and

        (d)     Any other form or forms of insurance as Landlord, or Landlord's
mortgagees may reasonably require from time to time in form, in amounts, and for
insurance risks against which a prudent Landlord of a comparable size and in a
comparable business would protect itself.

        Section 15.05. Self Insurance and Blanket Insurance. Landlord and Tenant
shall have the right to satisfy its obligations under this Article through the
use of self-insurance and blanket insurance programs so long as the coverages,
and limits otherwise satisfy this Article. Tenant's rights under this Section
15.04 are personal to the Tenant named herein and its Parent or Affiliates (as
hereinafter defined).

                                  ARTICLE 16
                       DAMAGE BY FIRE OR OTHER CASUALTY

        Section 16.01. Termination Rights Due to Damage or Destruction to the
Premises.

        (a)     Landlord and Tenant shall each immediately notify the other of
any damage to the Building which affects the Premises.

        (b)     If all or any portion of the Premises are damaged and destroyed
(such area being hereinafter referred to as the "Damaged Area"), Landlord shall
cause Landlord's architect for the Building (the "Building Architect"), to
inspect the Premises. Within thirty (30) days after the damage and destruction,
the Building Architect shall complete its inspection and notify Landlord and
Tenant, in writing, of its findings (the "Damage Report").

        (c)     Should the Building Architect, in the exercise of its reasonable
objective opinion, determine in the Damage Report that the Damaged Area can be
rebuilt but either (i) the reconstruction can not be completed and the Damaged
Area made fit for Tenant's purposes within one hundred (100) days after the
damage or destruction, or (ii) when rebuilt, the Damaged Area cannot be
reasonably occupied or used for the continued operation of the Tenant's
business, then, in either case, Tenant shall have the right, at its sole option,
to terminate this Lease as it pertains to the Damaged Area. In such case, Tenant
may exercise its right to terminate this Lease by giving written notice to
Landlord, within sixty (60) days after receipt of the Damage Report.

        (d)     Should the Damage Report reveal that the provisions of
subparagraph (c) of this Section do not apply and the Damaged Area can be
rebuilt and made fit for Tenant's continued use, but the proceeds of the
insurance which Tenant is required to maintain under Section 15.01(c) that was
intended to cover the Tenant's Property, are insufficient to repair or restore
the damage or destruction, then Landlord and Tenant will each have a right to
terminate this Lease as it pertains to the Damaged Area. In such case, Landlord
or Tenant may exercise their respective

                                      -28-
<PAGE>

right to terminate as to the Damaged Area, by giving notice to the other, within
sixty (60) days after receipt of the Damage Report.

        Section 16.02. Damage to the Building.

        (a)     If the Building or any portion thereof (excluding the Premises)
is damaged or destroyed by any cause whatsoever, to the extent that in
Landlord's reasonable judgment, it would not be economically feasible to repair
or restore such damage or destruction, Landlord may, at its option, terminate
this Lease by giving Tenant notice of such termination within sixty (60) days
after such damage or destruction.

        (b)     Provided the provisions of subparagraph (a) are not applicable
the Building Architect will notify Landlord and Tenant, if, in the Building
Architect's reasonable objective judgment, the damage or destruction to the
Building I cannot be repaired or restored within three hundred sixty (360) days
after such damage or destruction. Landlord or Tenant shall have the right, at
the option of either party, to terminate this Lease. In such case, Landlord or
Tenant may exercise their respective right to terminate this Lease by giving
written notice to the other, within sixty (60) days after receipt of the
Building Architect's notification and thereupon the provisions of Section 16.06
hereof shall apply.

        (c)     If any portion of the Building (excluding the Premises) is
damaged or destroyed by any cause whatsoever to the extent that the Building
Architect determines that such damage makes it reasonably impossible for Tenant
to continue to use or occupy the Premises, then either Landlord or Tenant shall
have the right, at the option of either party, to terminate this Lease as to the
portion of the Premises affected by such damage or destruction by giving the
other, within sixty (60) days after such damage or destruction, written notice
of termination, and thereupon Rent and any other payments for which Tenant is
liable under this Lease for the portion of the Premises affected shall be
apportioned and paid to the date of such damage, and Tenant shall immediately
vacate the affected portion of the Premises; provided, however, that those
provisions of this Lease which are designated to cover matters of termination
and the period thereafter shall survive the termination hereof.

        Section 16.03. Partial Damage. In the event of partial destruction or
damage to the Building or the Premises which does not result in a complete
termination of this Lease pursuant to Sections 16.01 and 16.02 hereof, this
Lease shall not terminate and Rent shall be abated in proportion to the area of
the Premises which, in the Building's Architect's reasonable objective opinion,
cannot be used or occupied by Tenant as a result of such casualty. Landlord
shall in such event, within a reasonable time after the date of such destruction
or damage, restore the Premises to as near the same condition as existed prior
to such partial damage or destruction, provided that Tenant shall be responsible
for restoring its personal property. Upon such reconstruction, the Rentable Area
of the Premises will be recomputed and Tenant's Proportionate Share adjusted
accordingly.

        Section 16.04. Damage During Last Year of Term. If the Building or the
Premises or any substantial portion thereof is destroyed by fire or other causes
at any time during the last year of the Term, then either Landlord or Tenant
shall have the right, at the option of either party, to

                                      -29-
<PAGE>

terminate this Lease by giving written notice to the other within sixty (60)
days after the date of such destruction, and Tenant shall immediately vacate the
Premises and, upon Tenant's vacation of the Premises, this Lease shall
terminate.

        Section 16.05. No Landlord Liability. Landlord shall have no
responsibility to restore the Tenant's personal property, except as specifically
provided in Sections 16.01(d) and 16.03. Landlord shall have no liability to
Tenant for inconvenience, loss of business, or annoyance arising from any repair
of any portion of the Premises or the Building. If Landlord is required by this
Lease or by any lender or lessor of Landlord to repair or if Landlord undertakes
to repair, Tenant shall pay to Landlord that amount of Tenant's insurance
proceeds which insures such damage as a contribution towards such repair, and
Landlord shall use reasonable efforts to have such repairs made promptly and in
a manner which will not unnecessarily interfere with Tenant's use and occupancy.
Notwithstanding the foregoing, if such repairs continue for two (2) consecutive
days and make it reasonably impossible for Tenant to continue to occupy, operate
and/or use the Premises, Tenant shall be entitled an abatement of Rent payable
at the time of such disruption for the portion of the Premises affected by the
repairs for the period commencing on the date of the interruption caused by the
repairs, and continuing until the earlier of (i) the date such repair is
completed, or (ii) the date such disruption ceases. However, should Tenant
recommence its use, occupancy and/or operations in any part of the Premises
which was affected by the repairs, notwithstanding the fact that the repairs may
not have been completed, Tenant's right to abate Rent for the reoccupied portion
of the Premises will terminate.

        Section 16.06. Apportionment of Rent. In the event of termination of
this Lease pursuant to Section 16.01, then all Rent shall be apportioned and
paid to the date on which possession is relinquished or the date of such damage,
whichever last occurs, and Tenant shall immediately vacate the Premises
according to such notice of termination and upon such vacation, the Lease will
terminate as to the portion of the Premises affected thereby.

                                  ARTICLE 17
                                 CONDEMNATION

        Section 17.01. Entire Building. In the event that the whole or
substantially the whole of the Building and/or the Premises are taken or
condemned for any public purpose, this Lease and the leasehold estate created
hereby shall cease and terminate as of the date of such taking.

        Section 17.02. Partial Takings Affecting the Premises.

        (a)     In the event that either (i) a portion, but less than
substantially the whole, of the Premises should be taken or condemned for any
public purpose, and the remainder of the Premises cannot be reasonably used for
the continued operation of Tenant's business or (ii) a portion, but not all, of
the Building is taken and such taking makes it reasonably impossible for Tenant
to continue to occupy, operate and/or use the Premises, then in either event,
either party may terminate this Lease by written notice to the other given
within thirty (30) days of such taking and then this Lease shall be terminated
as of the date of such taking.

                                      -30-
<PAGE>

        (b)     For all circumstances not addressed in Sections 17.01 and
17.02(a), in the event of a partial taking of the Premises, this Lease shall be
terminated as of the date of such taking as to the portion of the Premises so
taken or affected by such taking, and, this Lease shall remain in full force and
effect as to the remainder of the Premises. In such event, the Rent will be
diminished by an amount representing the part of such amounts properly
applicable to the portion of the Premises so taken. Further, in such event
Tenant's Proportionate Share shall be recomputed based upon the remaining
Rentable Area in the Premises and in the Building.

        Section 17.03. Termination of Lease. In the event of the termination of
this Lease pursuant to the provisions of this Article 17, this Lease and the
Term and the estate hereby granted shall expire as of the date of such
termination in the same manner and with the same effect as if that were the date
set for the normal expiration of the Term of this Lease, and the Rent shall be
apportioned as of such date.

        Section 17.04. Landlord's Right to Award. All awards, damages, and other
compensation paid by the condemning authority on account of such taking or
condemnation (or sale under threat of such a taking) shall belong to Landlord,
and Tenant hereby assigns to Landlord all rights to such awards, damages and
compensation. Tenant agrees not to make any claim against Landlord or the
condemning authority for any portion of such award or compensation attributable
to damages to the Premises, the value of the unexpired term of this Lease, the
loss of profits or goodwill, Leasehold Improvements paid by Tenant by the use of
the Tenant Allowance or severance damages. Nothing contained herein, however,
shall prevent Tenant from pursuing a separate claim against the condemning
authority for the value of Leasehold Improvements paid by Tenant from funds
other than the Tenant Allowance, Alterations paid by Tenant, furnishings,
equipment, and trade fixtures installed in the Premises at Tenant's expense and
for relocation expenses.

                                  ARTICLE 18
                          ASSIGNMENT AND SUBLETTING

        Section 18.01. Permitting Subletting of the Premises.

        (a)     Tenant shall have the right to sublet the Premises without the
prior consent of Landlord so long as

        (i)     the sublease has provisions which satisfy Section 18.03 hereof;

        (ii)    the entity, organization or individual to which the space is
                sublet satisfies the requirements of Section 18.02(b)(ii) and
                (iii) hereof; and

        (iii)   the total Rentable Area of the Premises occupied by Tenant or
                its Permitted Occupants is not less than 50% of the Rentable
                Area demised by this Lease.

        (b)     In the event of a sublease, Tenant shall submit to Landlord
evidence that the provisions of Section 18.01(a) have been satisfied. Should the
sublease result in a violation of the

                                      -31-
<PAGE>

provisions of Section 18.01(a) then such sublease shall be subject to the
provisions of Section 18.02 hereof.

        (c)     Notwithstanding the foregoing or the provisions of Section 18.02
hereof, the Premises or any part thereof shall not be publicly advertised in
newspapers or other mass media for subletting at a rental rate less than the
rental rate being sought by Landlord for space in the Building (provided that
Landlord shall, within ten (10) days after Tenant so requests, have informed
Tenant of the rental rate being sought by Landlord for such space), and all
advertisements (in newspapers or other mass media) of the Premises or any
portion thereof for subletting shall not include the name of the Building
(without Landlord's prior written consent which will not be unreasonably
withheld). The foregoing, however, shall not be deemed to prohibit Tenant from
negotiating or consummating a sublease at a lower rental rate.

        Section 18.02. Rights of Tenant.

        (a)     Except as permitted by Sections 18.01(a) and 18.06 hereof,
Tenant may not sell, assign, transfer, or hypothecate this Lease or any interest
herein (either voluntarily or by operation of law, and including, if Tenant is a
corporation or partnership, the sale or transfer of a controlling interest in
Tenant), or sublet the Premises or any part hereof without the prior written
consent of Landlord, which shall not be unreasonably withheld, conditioned or
delayed. If Tenant should desire to assign this Lease or sublet the Premises (or
any part thereof), Tenant shall give Landlord written notice at least fifteen
(15) days in advance of the date on which Tenant desires to make such assignment
or sublease. Landlord shall then have a period of ten (10) days following
receipt of such notice within which to notify Tenant in writing that landlord
elects:

        (i)     to permit Tenant to assign or sublet such space, subject,
                however, to the subsequent written approval by Landlord of the
                instrument of assignment or sublease as to form and substance;
                or

        (ii)    to refuse, in Landlord's reasonable discretion, to consent to
                Tenant's assignment or subleasing of such space and to continue
                this Lease in full force and effect as to the entire Premises.
                If Landlord should fail to notify Tenant in writing of such
                election within such ten (10) day period, Landlord shall be
                deemed to have elected option (i) above.

        Except as may be otherwise expressly set forth to the contrary in
Landlord's consent to the assignment, no assignment by Tenant shall relieve
Tenant of Tenant's obligations under this Lease. Any attempted assignment or
sublease by Tenant which is not permitted by Section 18.01 and 18.06 hereof and
is in violation of the terms and provisions of this Section shall be void.

        (b)     Landlord's consent under this Section 18.02(a) to an assignment
or sublease will not be withheld provided all of the following conditions have
been satisfied:

        (i)     if a sublease, the sublease has provisions which satisfy Section
18.03 hereof;

                                      -32-
<PAGE>

        (ii)    if an assignment, (a) the assignee shall agree, in a written
                agreement satisfactory to Landlord, to assume and abide by all
                of the terms and provisions of this Lease (but without liability
                to matters arising prior to the date of the assignment); and (b)
                the assignee has submitted a current financial statement
                reasonably acceptable to Landlord, showing a net worth and
                working capital in amounts reasonably determined by Landlord to
                be sufficient to assure the future performance by such assignee
                of Tenant's obligations hereunder; and

        (iii)   the entity, organization, or individual to which such space is
                proposed to be sublet or to which the Lease is proposed to be
                assigned is not of a type that would be an undesirable tenant in
                a first-class office complex in Fair Lakes, or of a type that
                because of its controversial or unsavory nature, might bring
                undue notoriety or disruption to the Building.

        Section 18.03. Required Provision in Sublease. A sublease of portions of
the Premises, must include (or shall be deemed to include) provisions stating
that it is subject and subordinate to this Lease and to the matters to which
this Lease is or shall be subordinate, and that in the event of the termination
of this Lease, or the re-entry or dispossession of Tenant by Landlord under this
Lease, the sublease shall also terminate and the subtenant shall peacefully
vacate the premises sublet.

        Section 18.04. Excess Rent. In the event that (i) the total Rentable
Area of the Premises occupied by Tenant or its Permitted Occupants is less than
50% of the Rentable Area of the Premises; and (ii) if the rent agreed upon
between Tenant and its proposed subtenant under any proposed sublease of the
Premises (or any part thereof) is greater than the Rent that Tenant must pay
Landlord hereunder for that portion of the Premises that is subject to such
proposed sublease and at the time of the transaction Tenant is not in Default
hereunder, then one-half of such excess rent (after deducting therefrom the
reasonable costs involved in the transaction, which costs include, without
limitation, brokerage commissions, marketing costs, construction expenses,
tenant concessions, and legal fees) shall be considered Additional Rent owed by
Tenant to Landlord, and shall be paid by Tenant to Landlord in the same manner
that Tenant pays Rent under this Lease. Notwithstanding the foregoing, if at the
time of the assignment or sublease Tenant is in Default hereunder, then until
such Default has been cured by Tenant (i) all such excess rent arising prior to
the cure shall be considered Additional Rent owed by Tenant to Landlord and
shall be paid by Tenant to Landlord in the same manner that Tenant pays Rent
under this Lease, and (ii) all costs associated with the transaction shall be
borne by Tenant and will not be deducted in determining the excess rent payable
to Landlord hereunder.

        Section 18.05. Rights of Landlord. Landlord may sell, transfer, assign,
and convey, all or any part of the Building and/or the Land and any and all of
its rights under this Lease, and in the event Landlord assigns its rights under
this Lease, Landlord shall be released from any further obligations hereunder
which arise after the date of the transfer, and Tenant agrees to look solely to
Landlord's successor in interest for performance of such obligations.

                                      -33-
<PAGE>

        Section 18.06.   Permitted Occupants. Notwithstanding the provisions
of Section 18.01 hereof, Tenant shall have the right, without the prior written
consent of Landlord to assign its entire interest in this Lease to an Affiliate
(hereinafter defined) so long as (i) the Affiliate delivers to Landlord,
concurrently with such assignment, a written notice of the assignment and an
assumption agreement whereby the Affiliate assumes and agrees to perform,
observe and abide by the terms, conditions, obligations and provisions of this
Lease applicable to Tenant and (ii) the entity remains an Affiliate. Further,
Tenant shall also have the right, without the prior written consent of
Landlord, to sublet all or any portion of the Premises to an Affiliate so long
as (i) such sublease is expressly subject to the terms of this Lease so that a
termination of this Lease shall result in the termination of the sublease and
(ii) the entity remains an Affiliate. No assignment or subletting by Tenant
shall relieve Tenant of Tenant's obligations under this Lease. As used herein,
the term Affiliate shall mean and collectively refer to (i) a parent
corporation (the "Parent") of the Tenant which owns and controls not less than
fifty-one percent (51%) of the voting stock of the Tenant and is able to elect
(by ownership of stock or by proxy) the board of directors and the officers of
Tenant, or (ii) a corporation in which either the Tenant or its Parent owns and
controls not less than fifty-one percent (51%) of the voting stock of the
corporation and is able to elect (by ownership of stock or proxy) the board of
directors and the officers of the corporation, or (iii) an Affiliate of the
Parent, and/or (iv) a successor or surviving corporation in the event of a
merger, takeover or other form of corporation acquisition of the Tenant. In
addition to the foregoing, Tenant shall also have the right, without the prior
consent of Landlord, to sublet portions of the Premises to any entity,
organization or individual who is either a contractor or subcontractor of
Tenant or its Affiliate or with whom the Tenant or its Affiliates are a
contractor or subcontractor so long as (i) the terms of the sublease satisfy
the provisions of Section 18.03 hereof and (ii) the total Rentable Area
occupied by such subtenants (or subtenants permitted by Section 18.01 hereof)
does not exceed an aggregate of 50% of the Rentable Area of the Premises. A
transfer permitted under this Section 18.06 will be excluded from the
provisions of Section 18.04 hereof. Entities permitted by this Section 18.06
are collectively referred to as "Permitted Occupants".

                                  ARTICLE 19
                               INDEMNIFICATION

        The Tenant shall indemnify the Landlord and hold the Landlord harmless
from and against all loss or liability for or on account of any injury
(including death) or damage received or sustained by any person or persons
(including the Landlord and any employee, agent or invitee of any of them) to
the extent that such loss or liability is (i) caused by reason or any negligent
act or omission on the part of the Tenant or any employee, representative, or
business visitor of the Tenant and (ii) not covered by insurance maintained by
Landlord pursuant to this Lease.

        The Landlord shall indemnify the Tenant and hold the Tenant harmless
from and against all loss or liability for or on account of any injury
(including death) or damage received or sustained by any person or persons
(including any employee, agent or invitee of the Tenant) to the extent that such
loss or liability is (i) caused by reason of any negligent act or omission on
the part of Landlord or any employee, representative or business visitor of
Landlord and (ii) not covered by insurance maintained by Tenant pursuant to this
Lease.

                                      -34-
<PAGE>

        If either Landlord or Tenant (the "Indemnitee") is made a party to any
litigation commenced against the Indemnitee which falls within the scope of the
foregoing indemnities, then the other party (the "Indemnitor") shall pay all
costs and expenses, including reasonable attorneys, fees and court costs,
incurred by or imposed upon Indemnitee because of any such litigation, and the
amount of such costs and expenses, including reasonable attorneys' fees and
court costs, shall be a demand obligation owing by Indemnitor to Indemnitee.

                                  ARTICLE 20
                          SURRENDER OF THE PREMISES

        Section 20.01. Condition of Premises. Upon expiration of the Term or
other termination of this Lease for any cause whatsoever, Tenant shall
peacefully vacate the Premises in as good order and condition as the same were
at the beginning of the Term or may thereafter have been improved by Landlord or
Tenant, except for reasonable use and wear thereof, and damage to the Premises
or the Leasehold Improvements by fire or other casualty or condemnation.

        Section 20.02. Tenant Holdover. In the event that Tenant shall not
immediately surrender the Premises on the Expiration Date of the Term, Tenant
shall become a month-to-month Tenant subject to all of the terms, conditions,
covenants and agreements of this Lease; however, during the first ninety (90)
days of the holdover Rent will be 125% of the Rent paid during the last month of
the Term; thereafter it will be 150%. However, if Landlord has notified Tenant
that it has relet all or any portion of the Premises and Tenant fails to vacate
the Premises within thirty (30) days after the date of Landlord's notice, then
Tenant shall reimburse Landlord for the costs and damages incurred by Landlord
for failing to deliver the space but in no event will it be greater than 150% of
the Rent. Tenant shall give to Landlord at least thirty (30) days' written
notice of any intention to quit the Premises, and Tenant shall be entitled to
thirty (30) days' written notice to quit the Premises, unless Tenant is in
Default hereunder, in which event Tenant shall not be entitled to any notice to
quit, the usual thirty (30) days written notice being hereby expressly waived.
Notwithstanding the foregoing provisions of this Section, in the event that
Tenant shall hold over after the expiration of the Term, then at any time prior
to Landlord's acceptance of Rent from Tenant as a monthly tenant hereunder,
Landlord, at its option, may forthwith re-enter and take possession of the
Premises without process, or by any legal process in force in the Commonwealth
of Virginia. Tenant shall be liable to Landlord for all damage which Landlord
suffers because of any holding over by Tenant, and Tenant shall indemnify
Landlord against all claims made against Landlord resulting from Landlord's
delay in delivering possession of the Premises to any other tenant or
prospective tenant.

                                  ARTICLE 21
                            ESTOPPEL CERTIFICATES

        Landlord and Tenant each agree that, upon request of a party (the
"Requesting Party"), the other (the "Responding Party") will execute and return,
within fifteen (15) calendar days after the Requesting Party's request, any
certificate that the Requesting Party may request from time to time, stating
that this Lease is unmodified and in full force and effect, or in full force and
effect as modified, and stating the modification. The certificate also shall
state, if true, (i) that all

                                      -35-
<PAGE>

work has been completed, and the work and the Premises are accepted as
satisfactory except for items listed on a punchlist, if any, attached to such
certificate; (ii) the amount of Base Rent and Additional Rent and the dates on
which Rent commenced to accrue and to which the Rent has been paid in advance,
and the amount of any security deposit or prepaid Rent; (iii) that, to the best
of the Responding Party's knowledge, Tenant is in full and complete possession
of the Premises and doing business; (iv) that there is no present default on the
part of the Requesting Party, or attach a memorandum stating any such instance
of default; (v) that the Responding Party has not advanced any amounts to or on
behalf of the Requesting Party which have not been reimbursed; (vi) that, to the
best of Responding Party's knowledge, the Responding Party has no rights to
setoff and no defense or counterclaim against enforcement of its obligations
under the Lease, including the payment of Rent; (vii) that there are no actions,
whether voluntary or otherwise, pending against the Responding Party under the
bankruptcy laws of the United States or any state thereof; and (viii) any other
fact pertaining to this Lease which the Requesting Party may reasonably request.
Failure to deliver the certificate within the fifteen (15) calendar days shall
be conclusive upon the Responding Party for the benefit of the Requesting Party
and its successor that this Lease is in full force and effect and has not been
modified except as may be represented by the party requesting the certificate.

                                  ARTICLE 22
                         SUBORDINATION AND ATTORNMENT

        Section 22.01. Existing Financings.

        (a)     This Lease is subject and subordinate to any deeds of trust or
other security instruments which, as of the date of this Lease, cover the
Building, the underlying land, or any interest of Landlord therein, and to any
advances made on the security thereof, and to any increases, renewals,
modifications, consolidations and extensions of any of such deeds of trust or
security instruments (the "Existing Indebtedness"). This provision is declared
by Landlord and Tenant to be self-operative and no further instrument shall be
required to effect such subordination of this Lease. Upon demand, however,
Tenant shall execute, acknowledge, and deliver to Landlord any further
instruments and certificates evidencing such subordination as Landlord, or the
holder of the Existing Indebtedness may reasonably require.

        (b)     Landlord agrees to obtain from the holder of the Existing
Indebtedness a Subordination, Non-Disturbance and Attornment Agreement, in form
attached hereto as Exhibit "H" (and by this reference incorporated herein),
which provides that, in the event of a foreclosure or a transfer in lieu
thereof, Tenant will not be disturbed in its possession and this Lease shall,
notwithstanding the foreclosure or transfer in lieu thereof, continue in full
force and effect upon and subject to all terms, covenants, conditions, and
obligations of this Lease so long as (i) no Default has occurred on the part of
Tenant under this Lease and (ii) Tenant attorns to the purchaser or transferree
as landlord under this Lease.

        Section 22.02. Future Financings. During the Term of this Lease,
Landlord reserves the right to encumber its interest in this Lease, the Building
and/or the underlying land, by new or additional deeds of trust or other
security instruments and to refinance the Existing Indebtedness

                                      -36-
<PAGE>

(the "New Financing"). Tenant agrees to subordinate this Lease to any New
Financing so long as the holder of the New Financing executes and delivers to
Tenant a Subordination, Non-Disturbance and Attornment Agreement which contains
the provision set forth in Section 22.01(b) hereof and is otherwise a
commercially reasonable instrument.

        Section 22.03. Attornment. Provided the holder of the Existing
Indebtedness and New Financing has delivered to Tenant a Subordination,
Non-Disturbance and Attornment Agreement which satisfies the provisions of
Section 22.01(b) hereof, Tenant shall attorn to the purchaser upon a sale or to
the grantee under any deed in lieu of foreclosure and shall recognize such
purchaser or grantee as Landlord under this Lease without any change in the
terms or other provisions of this Lease. In such agreement, Tenant will waive
the right, if any, to elect to terminate this Lease or to surrender possession
of the Premises in the event of foreclosure of any deed of trust or security
instrument (or any transfer in lieu thereof).

                                  ARTICLE 23
                               QUIET ENJOYMENT

        Provided there is no Event of Default by Tenant of its obligations under
this Lease, Tenant shall, during the Term, peaceably and quietly enjoy the
Premises without disturbance from Landlord or any other persons acting by,
through, or under Landlord; subject, however, to (i) the terms of this Lease;
(ii) the Existing Indebtedness and New Financings (which satisfy the provisions
of Section 22.02 hereof) ordinances, restrictive covenants, leases, easements,
and other agreements or encumbrances now or hereafter affecting the Building or
the land on which the Building is situated; (iii) the right of Landlord to
construct on its property any additional buildings or other improvements now or
hereafter permitted by the governmental authorities having jurisdiction over
Landlord's property; and (iv) the right of Landlord to relocate parking spaces
for the Building, conduct renovations for the Building or make alterations to
the Building so long as Landlord's exercise of the rights reserved under
subparagraphs (iii) and (iv) does not substantially interfere with Tenant's use
of the Premises. This covenant and all other covenants of Landlord in this Lease
shall be binding upon Landlord and its successors only with respect to breaches
occurring during its and their respective ownership of Landlord's interest
hereunder.

                                  ARTICLE 24
                            SIGNS AND FURNISHINGS

        Section 24.01. Signs and Advertisements. No sign, advertisement, or
notice referring to Tenant shall be inscribed, painted, affixed, or otherwise
displayed on any part of the exterior of the Premises or the exterior or the
interior of the Building (if visible to the exterior of the Premises), except
those permitted by Section 24.02 or those installed by Landlord on the
directories and the entrance door to the Premises and such other areas, if any,
as Landlord may determine. Tenant may also install, without the prior consent of
Landlord, locational and directional signage and suite or room numbers within
the Premises so long as the same is not visible to the exterior of the Premises.
If Tenant exhibits or installs any sign, advertisement or notice, without the
prior consent of Landlord, Landlord shall have the right to remove the same at
Tenant's expense.

                                      -37-
<PAGE>

Landlord shall have the right to prohibit any advertisement of or by Tenant
which in its opinion tends to impair the reputation of the Building or its
desirability as a high-quality office building and, upon written notice from
Landlord, Tenant shall immediately refrain from and discontinue any such
advertisement. Landlord reserves the right to affix, install, and display signs,
advertisements, and notices on any part of the exterior or interior of the
Building, however, Landlord's right to install exterior signage for any other
tenant in the Building is subject to the provisions of Section 24.02 hereof.
Landlord shall not, however, have the right to affix upon the exterior of the
Building "for lease" or similar signs advertising the availability of space for
lease in the Building, however, Landlord may utilize monument signage similar to
those in existence for the Building on the date of this Lease.

        Section 24.02. Building Signage.

        (a)     Notwithstanding the provisions of Section 24.01 hereof, Tenant
shall have the right, subject to the provisions of this Section 24.02, to
install, at its sole cost one building identification sign showing the
Tenant's corporate logo. The sign will be located on the roofline of the western
(or I-66) side of the Building. The exact location, size, design, appearance,
and finish of the sign shall be subject to the approval of all applicable
governmental authorities, the Architectural Review Board of Fair Lakes
(established by the Fair Lakes League to which the Building is subject) and
Landlord. Landlord shall use its best efforts to promptly obtain the approval of
the Architectural Review Board of Fair Lakes.

        (b)     Landlord covenants and agrees that, during the Term, no more
than two (2) building identification signs (including the sign erected by Tenant
pursuant to Section 24.02(a)) may be erected upon the exterior of the Building
without the prior consent of Tenant which consent shall not be unreasonably
withheld. Notwithstanding the foregoing, upon the vacation of AETNA Life and
Casualty, as a tenant in the Building, Landlord reserves the right to replace
the Building rooftop sign for AETNA with a sign of a tenant occupying not less
than two floors of the Building or 45,000 square feet of Rentable Area (the
"Other Tenant"), however, (i) the sign of the other Tenant will be removed if
Tenant and its Permitted Occupants occupy 50% or more of the Rentable Area in
the Building or five (5) full floors of the Building, and (ii) Tenant shall have
the only sign along the rooftop of the Building for so long as it and its
Permitted Occupants occupy more than 50% of the Rentable Area in the Building or
five (5) full floors of the Building. Landlord specifically reserves the right,
during foregoing period, to install signage on the exterior of the first floor
of the Building.

        Section 24.03. Furnishings. The Building is designed with a floor load
design capacity of 100 pounds per square foot of live load. In no event shall
Tenant place on any part of the floor of the Premises a load exceeding the
foregoing floor load per square foot and which is allowed by law. Any and all
damage or injury to the Premises or the Building caused by Tenant moving heavy
equipment or fixtures or the same being in or upon the Premises by Tenant, shall
be repaired by and at the sole cost of Tenant. All furniture, equipment, and
other bulky matter of any description shall be delivered to the Premises only
through the designated service entrance of the Building and the designated
service elevator during normal business hours or as otherwise directed or
scheduled by Landlord. All moving of furniture, equipment and other materials
shall

                                      -38-
<PAGE>

be under the supervision of Landlord, who shall not, however, be responsible for
any damage to or charges for moving the same. Tenant agrees to remove promptly
from the sidewalks adjacent to the Building any of Tenant's furniture,
equipment, or other material there delivered or deposited.

        Section 24.04. Satellite Dish.

        (a)     Tenant shall have the right, subject to the provisions of this
Section 24.04, to install, at its sole cost and expense, upon the roof of the
Building a satellite dish antenna. The location of the antenna shall be mutually
agreed upon by Landlord and Tenant prior to the Commencement Date. The size,
design, and appearance of the antenna shall be subject to the approval of all
applicable governmental authorities, the Architectural Review Board of Fair
Lakes and Landlord.

        (b)     In the event that Tenant constructs the antenna then, such
construction shall be subject to all of the provisions of this Lease, including,
but not limited to Article 12 and 13 hereof. Tenant further agrees that the
provisions of Article 19 hereof shall apply to Tenant's use of the roof for the
installation and operation of the antenna. Tenant shall maintain the antenna and
the portion of the roof upon which it is situated in a good, clean and proper
condition and will, at the end of the Term, remove the antenna and restore the
portion of the roof affected thereby as required by Article 12 and 20 hereof.

                                  ARTICLE 25
                            DEFAULTS AND REMEDIES

        Section 25.01. Events of Default. The occurrence of any one or more of
the following events shall constitute a Default or an Event of Default under
this Lease: (a) if Tenant fails to pay any Base Rent, Temporary Rent and/or
Additional Space Rent hereunder as and when the same becomes due and such
failure shall continue for more than fifteen (15) days after Landlord gives
Tenant notice that such payment is past due; (b) if Tenant fails to pay any
installment of Additional Rent hereunder within thirty (30) days after Landlord
gives notice that such payment is due; (c) if Tenant fails to take possession of
either (i) the Phase I Space on the Phase I Rent Commencement Date or promptly
thereafter or (ii) the Phase II Space on the Phase II Rent Commencement Date or
promptly thereafter; (d) if Tenant permits to be done anything which creates a
lien upon the Premises and fails to discharge, or bond such lien or post such
security with Landlord as is required by Article 13; (e) if Tenant violates the
provisions of Article 18 by attempting to make an unpermitted assignment or
sublease; (f) if Tenant fails to maintain in force all policies of insurance
required by this Lease and any such failure shall continue for more than ten
(10) days after Landlord gives Tenant notice of such failure; (g) if any
petition is filed by or against Tenant under any present or future section or
chapter of the Bankruptcy Code, or under any similar law or statute of the
United States or any state thereof (which, in the case of an involuntary
proceeding, is not permanently discharged, dismissed, stayed or vacated, as the
case may be, within ninety (90) days of commencement), or if any order for
relief shall be entered against Tenant in any such proceedings; (h) if Tenant
becomes insolvent or makes a transfer in fraud of creditors or makes an
assignment for the benefit of creditors; (i) if a receiver, custodian, or trus-

                                      -39-
<PAGE>

tee is appointed for the Premises or for all or substantially all of the assets
of Tenant, which appointment is not vacated within ninety (90) days following
the date of such appointment; or (j) if Tenant fails to perform or observe any
other term of this Lease and such failure shall continue for more than thirty
(30) days after Landlord gives Tenant notice of such failure, or, if such
failure cannot be corrected within such thirty (30) day period, if Tenant does
not commence to correct such default within said thirty (30) day period and
thereafter diligently prosecute the correction of same to completion within a
reasonable time and in any event prior to the time a failure to complete such
correction could cause Landlord to be subject to prosecution for violation of
any law, rule, ordinance or regulation or causes, or could cause a default under
any deed of trust, mortgage, underlying lease, Tenant lease or other agreement
applicable to the Project and/or Building.

        Section 25.02. Remedies. Upon the occurrence of any Event of Default,
Landlord shall have the right, at Landlord's option, to terminate this Lease.
With or without terminating this Lease, Landlord may re-enter and take
possession of the Premises and the provisions of this Section 25.02 shall
operate as a notice to quit, any other notice to quit or of Landlord's intention
to reenter the Premises being hereby expressly waived. If necessary, Landlord
may proceed to recover possession of the Premises under and by virtue of the
laws of the Commonwealth of Virginia or by such other proceedings, including
re-entry and possession, as may be applicable. If Landlord elects to terminate
this Lease, everything contained in this Lease on the part of Landlord to be
done and performed shall cease without prejudice; subject however, to the right
of Landlord to recover from Tenant all rent and other sums accrued up to the
time of termination or recovery of possession by Landlord, whichever is later.
Whether or not this Lease is terminated by reason of Tenant's Default, Landlord
may, but shall not be obligated to, relet the Premises for such rent and upon
such terms as are not unreasonable under the circumstances and, if the entire
Rent provided in this Lease plus the costs, expense, and damages hereafter
described shall not be realized by Landlord, Tenant shall be liable for all
damages sustained by Landlord, including, without limitation, attorney's fees
and expenses reasonably incurred, brokerage fees, and the expense of placing the
Premises in first-class rentable condition. Landlord shall in no way be
responsible or liable for any failure to collect any rent due and/or accrued
from such reletting, to the end and intent that Landlord may elect to hold
Tenant liable for the Rent which Tenant shall have been obligated to pay
throughout the remainder of the Term. Landlord shall, however, use reasonable
efforts to relet the Premises and mitigate its damages. Any damages or loss of
rent sustained by Landlord may be recovered by Landlord, at Landlord's option,
at the time of the reletting or in separate actions, from time to time, as said
damage shall have been made more easily ascertainable by successive relettings,
or, at Landlord's option, may be deferred until the expiration of the Term, in
which event Tenant hereby agrees that the cause of action shall not be deemed to
have accrued until the date of Expiration of the Term. In the event such damages
or loss of rent are recovered at the time of the reletting and the judgment
rendered in Landlord's favor requires the Tenant to pay for future losses
suffered by the Landlord, Tenant shall be liable for an amount equal to the
present value (as of the date of the judgment for Landlord) of the Rent which
would have been paid by Tenant for the remaining balance of the Term, but for
Tenant's Default, less the present value (as of the date of the judgment for
Landlord) of the revenue stream Landlord reasonably expects to receive over the
remainder of the Term as a result of the reletting of the Premises. For purposes
of the foregoing sentence, present value shall be determined by

                                      -40-
<PAGE>

discounting at a rate equal to one and one-half percentage points above the
discount rate then in effect at the Federal Reserve Bank nearest to the
Building. There shall be no discounting for present value for any judgment which
covers losses incurred by Landlord prior to the reletting or portions of the
award applicable to sums accruing prior to the date of the judgment. The
provisions contained in this Section 25.02 shall be in addition to, and shall
not prevent the enforcement of, any claim Landlord may have against Tenant for
anticipatory breach of this Lease.

        Section 25.03. Remedies Cumulative. All rights and remedies of Landlord
set forth herein are in addition to all other rights and remedies available to
Landlord at law or in equity. All rights and remedies available to Landlord
hereunder or at law or in equity are expressly declared to be cumulative. The
exercise by Landlord of any such right or remedy shall not prevent the
concurrent or subsequent exercise of any such right or remedy. No delay in the
enforcement or exercise of any right or remedy granted Landlord or Tenant under
this Lease shall constitute a waiver of any Default by the defaulting party
hereunder or of any rights or remedies in connection therewith available
hereunder to the non-defaulting party. No party shall be deemed to have waived
any Default by the other hereunder unless such waiver is set forth in a written
instrument signed by the party against the waiver is asserted. Any waiver in
writing shall be limited to its terms and shall not be construed as a waiver of
any covenant, condition, or agreement set forth in this Lease except as to the
specific circumstances described in such written waiver.

        Section 25.04. No Acceptance or Surrender. No act or thing done by
Landlord or its agents during the Term shall constitute an acceptance of an
attempted surrender of the Premises, and no agreement to accept a surrender of
the Premises shall be valid unless made in writing and signed by Landlord. No
re-entry or taking possession of the Premises by Landlord shall constitute an
election by Landlord to terminate this Lease, unless a written notice of such
intention is given to Tenant. Notwithstanding any such reletting or re-entry or
taking possession, Landlord may at any time thereafter terminate this Lease for
a previous Default. Landlord's acceptance of Rent following an Event of Default
hereunder shall not be construed as a waiver of such Event of Default unless the
payment cures such Event of Default.

        Section 25.05. Customs and Practices. No custom or practice which may
develop between the parties in the administration of the terms of this Lease
shall be construed to waive or lessen a party's right to insist upon strict
performance of the terms of this Lease.

        Section 25.06. Payment of Tenant's Obligations by Landlord. In the Event
of Default, Landlord may, but shall not be required to, make such payment or do
such act required to be performed by Tenant. If Tenant fails to act and Landlord
makes such payment or does such act, all costs and expenses incurred by
Landlord, plus interest thereon at the rate per annum which is two percent (2%)
higher than the "prime rate" published in the Money Rates section of the Wall
Street Journal (the "Default Rate"), from the date paid by Landlord to the date
of payment thereof by Tenant, shall be immediately paid by Tenant to Landlord;
provided, however, that nothing contained therein shall be construed as
permitting Landlord to charge or receive interest in excess of the maximum legal
rate then allowed by law. The taking of such action by Landlord shall not be
considered as a cure of such Default by Tenant or to prevent Landlord from
pursuing any remedy it is otherwise entitled to in connection with such Default.

                                      -41-
<PAGE>

        Section 25.07. Default by Landlord. Should Landlord breach any of its
warranties or representations herein set forth or fail to perform any of its
covenants herein contained, Tenant shall notify Landlord of such default or
breach and Landlord shall have a period of 30 days after receipt of written
notice to remedy such breach or default, except in an emergency or life
threatening situation, in which case Landlord shall have a reasonable period to
cure such situation. If such breach or default cannot be cured within such
period, Landlord shall have such additional period that shall be reasonably
necessary to remedy such breach or default provided that Landlord is diligently
and continuously pursuing such remedy and provided further that Tenant is not
materially damaged or prejudiced. Should Landlord fail to cure such breach or
default, Tenant shall have available to it the following remedies, as its sole
and exclusive remedies, Tenant specifically waiving any other remedy it may have
at law or at equity:

        (a)     Terminate this Lease in the event of a material default which
renders it reasonably impracticable to occupy the Premises;

        (b)     Bring suit against Landlord for specific performance;

        (c)     Pursue any other rights and remedies specifically granted to
Tenant hereunder; or

        (d)     For so long as Tenant or its Permitted Occupants are occupying
not less than 40% of the Rentable Area of the Building, if such breach or
default is under the provisions of Sections 7.01, 7.04 and 14.02 hereof or
Articles 8, 16 or 17 hereof, then Tenant shall have the right to cure such
breach or default only to the extent that it affects the Premises. In the event
that Tenant elects to exercise its rights under subparagraph (d), then the
following provisions shall apply:

        (i)     Tenant shall diligently and continuously pursue such cure until
                the default or breach is corrected;

        (ii)    Tenant shall perform such cure in a manner which, to the extent
                reasonably practicable, minimizes interference or disruption to
                the other tenants of the Building;

        (iii)   All such work shall be performed using firstclass materials, in
                a good and workmanlike manner consistent with all applicable
                governmental requirements;

        (iv)    Should Tenant be required to expend funds in its cure of the
                Landlord's breach of default, then all costs and expenses
                incurred by Tenant shall be due and payable by Landlord within
                fifteen (15) days of a receipt of written demand from Tenant for
                such payment accompanied by a reasonably detailed statement of
                expenditures together with invoices shall bear interest at the
                Default Rate, from the date paid by Tenant to the date of
                payment thereof by Landlord. In the event that such sum (and
                interest accruing thereon) is not paid within sixty (60) days
                after receipt of written demand from Tenant, then Tenant may
                deduct such amount (and interest accrued thereon) against the
                installments of Rent until paid in full.

        Tenant agrees to give written notice of any default by Landlord under
this Lease to any lender of Landlord secured by the Premises upon request
thereof by such lender and a reasonable

                                      -42-
<PAGE>

time within which to cure such default prior to Tenant taking any action to
remedy such default or cancel the Lease.

                                  ARTICLE 26
                               SECURITY DEPOSIT

        (a)     In the event Tenant desires to assign its interest in the Lease
and be relieved of continuing liability hereunder, Landlord may require, as a
condition to its consent to any such assignment, that the assignee posts a
security deposit (the "Security Deposit") equal to one (1) month Rent due under
the Lease at the time of the Assignment.

        (b)     The Security Deposit shall be security for the performance by
Tenant of all of Tenant's obligations, covenants, conditions, and agreements
under this Lease. Within thirty (30) days after the expiration of the Term, and
provided Tenant has vacated the Premises and is not in Default hereunder,
Landlord shall return the Security Deposit to Tenant, less such portion thereof
as Landlord shall have appropriated to satisfy any Default by Tenant hereunder.
In the event of any default by Tenant hereunder, Landlord shall have the right,
but shall not be obligated to use, apply or retain all or any portion of the
Security Deposit for (i) the payment of any Rent to which Tenant is in Default,
(ii) the payment of any amount which Landlord may spend or become obligated to
spend by reason of Tenant's Default, or (iii) the payment of any amount Landlord
may spend or become obligated to spend or for compensation of Landlord for any
losses incurred by reason of Tenant's Default, including, but not limited to,
any damage or deficiency arising in connection with the reletting of the
Premises. If any portion of the Security Deposit is so used or applied, within
three (3) business days after written notice to Tenant of such use or
application, Tenant shall deposit with Landlord an amount sufficient to restore
the Security Deposit to its original amount, and Tenant's failure to do so shall
constitute a Default under this Lease.

                                  ARTICLE 27
                            INTENTIONALLY OMITTED

                                  ARTICLE 28
                      ATTORNEY'S FEES AND LEGAL EXPENSES

        In any action or proceeding brought by either party against the other
under this Lease, the prevailing party shall be entitled to recover from the
other party reasonable attorneys' fees, and other reasonable legal expenses and
court costs incurred by such party in such action or proceeding as the court may
find to be reasonable.

                                  ARTICLE 29
                                   NOTICES

        Any notice or document required to be delivered hereunder shall be in
writing and shall be given or made or communicated by United States registered
or certified mail or by any overnight or express mail service which provides
receipts to indicate delivery, addressed to the parties hereto at the respective
addresses as specified in the Basic Lease Information, or at such other
addresses they have subsequently specified by written notice.

                                      -43-
<PAGE>

        All notices shall be effective upon being deposited in the manner
prescribed above, however, the time period in which a response to such notice
must be given shall commence to run from the date of receipt by the addressee
thereof as shown on the return receipt of the notice. Rejection or other refusal
to accept or the inability to deliver because of changed address of which no
notice was given, shall be deemed to be receipt of the notice as of the date of
such rejection, refusal or inability to deliver.

                                  ARTICLE 30
                            RIGHT OF FIRST REFUSAL

        Provided Tenant is not in Default under this Lease at the applicable
time, Tenant, during the Refusal Period (hereinafter defined), shall, in the
manner described by and in compliance with the terms and provision of this
Article 30 have a right of first refusal to expand the Premises to include all
or any portion of the Additional Space (hereinafter defined).

        (a)     If at any time during the Refusal Period Landlord shall either
(i) receive a bonafide offer from a third party to lease all or a portion of the
Additional Space, which Landlord is prepared to accept, or (ii) prepares a
proposal pertaining to all or a portion of the Additional Space which Landlord
is prepared to offer as a lease proposal to a third party, then in either such
event, landlord shall send a written notice (the "Offer Notice") to Tenant of
such proposal. The Offer Notice shall set forth in reasonable detail the size or
portion of the Additional Space subject to the Offer Notice, and shall contain
(or be deemed to contain) an offer to Tenant to lease the portion of the
Additional Space subject to the Offer Notice for the remaining Term of this
Lease on the same terms and conditions set forth in the Offer Notice. (Except
that the concessions offered to the third party pursuant to the proposal forming
the basis of the Offer Notice shall be appropriately prorated if the remaining
Term of this Lease is shorter than the term contemplated by the proposal forming
the basis of the Offer Notice.) Tenant may elect to accept the Offer Notice, by
giving written notice to Landlord of its election not less than ten (10) days
after receipt by Tenant of the Offer Notice.

        (b)     In the event Tenant responds within the ten (10) day period and
elects to accept the proposal set forth in the Offer Notice, then this Lease
shall automatically be amended to include within the Premises the portion of the
Additional Space subject to the Offer Notice. The rent payable for the
Additional Space subject to the Offer Notice (the "Additional Space Rent") will
be as set forth in the Office Notice and Tenant will be entitled to all rental
concessions set forth in the Offer Notice prorated as set forth in subparagraph
(a) hereof. Tenant will take the space subject to the Offer Notice in its "as
is" and "where as" condition, however, Landlord will (i) perform in the
Additional Space all work required by the Offer Notice; (ii) grant to Tenant any
construction allowances that may be set forth in the Offer Notice prorated as
set forth in subparagraph (a) hereof; and (iii) deliver such space upon
Substantial Completion of all improvements thereto. The provisions of this
subparagraph shall be self-enforcing without the need for any further act by
Landlord or Tenant.

        (c)     Should Tenant either fail to respond within the ten (10) days,
or elects not to accept the Offer Notice, then the Landlord shall be free to
execute a lease (the "Space Lease") for

                                      -44-
<PAGE>

the portion of the Additional Space subject to the Offer Notice on terms not
materially different than those set forth in the Offer Notice and thereupon such
space shall be automatically excluded from the Additional Space and the rights
of Tenant set forth in this Article, as they pertain to the portion of the
Additional Space which is subject to the Offer Notice, shall automatically
terminate and be of no further force or effect. The provisions of this
subparagraph shall be self-enforcing without the need for any further act by
Landlord or Tenant.

        (d)     Notwithstanding the foregoing provisions of subparagraph (c)
hereof, should Tenant either fail to respond within ten (10) days, or elects not
to accept the Offer Notice, then the portion of the Additional Space subject to
the Offer Notice shall again become a part of the Additional Space subject to
the provisions of this Article upon either (i) the expiration or termination of
the Space Lease or (ii) six (6) months after the date of an Offer Notice if
Landlord is unable, within such period of time, to execute a Space Lease for the
space subject to the Offer Notice.

        (e)     An election by Tenant under this Article shall be irrevocable.

        (f)     As used herein, the term "Refusal Period" shall mean and refer
to the period commencing on the Commencement Date and expiring upon the earlier
of (i) the date on which Tenant's rights under this Article with respect to the
Additional Space are terminated pursuant to subparagraphs (b) and (c) hereof or
(ii) the commencement of the last year of the Term of this Lease (as it may be
extended by the Renewal Terms).

        (g)     As used herein, the term "Additional Space" shall mean and refer
to all of the Rentable Area of the Building excluding the Premises.

        (h)     The rights granted Tenant hereunder are subject to the rights
granted to others pursuant to leases in effect in the Building as of the date
hereof.

                                  ARTICLE 31
                                MISCELLANEOUS

        Section 31.01. No Partnership. Nothing contained in this Lease shall be
construed as creating a partnership or joint venture of or between Landlord and
Tenant, or to create any other relationship between the parties hereto other
than that of Landlord and Tenant.

        Section 31.02. Brokers. Landlord recognizes the Broker as the Broker
under this Lease and shall pay the Broker a commission pursuant to a separate
agreement between the Landlord and Broker. Landlord and Tenant each represent
and warrant to the other that, except as provided above, neither of them has
employed or dealt with any broker, agent or finder in carrying on the
negotiations relating to this Lease. In the event of a breach by a party of
their foregoing representation and warranty (the "Defaulting Party"), the
Defaulting Party shall indemnify and hold the other party harmless from and
against any claim or claims, damages or expenses (including any claims for
brokerage or other commissions asserted by broker, agent or finder fees) which
may arise as a result of such breach.

                                      -45-
<PAGE>

        Section 31.03. Severability. Every agreement contained in this Lease is,
and shall be construed as, a separate and independent agreement. If any term of
this Lease or the application thereof to any person or circumstances shall be
invalid and unenforceable, the remainder of this Lease, or the application of
such term to persons or circumstances other than those as to which it is invalid
or unenforceable, shall not be affected.

        Section 31.04. Trial by Jury. Landlord and Tenant each hereby waive
trial by jury in any action, proceeding or counterclaim brought by either of
them against the other in connection with any matter arising out of or in any
way connected with this Lease, the relationship of landlord and tenant
hereunder, Tenant's use or occupancy of the Premises, or any claim of injury or
damage.

        Section 31.05. Force Majeure. Whenever a period of time is herein
prescribed for action to be taken by a party, the party shall not be liable or
responsible for, and there shall be excluded from the computation for any such
period of time, any delays due to strikes, riots, acts of God, shortages of
labor or materials, war, governmental laws, regulations, or restrictions, or any
other cause of any kind whatsoever which is beyond the reasonable control the
party. However, the failure or inability to obtain or have funds required for a
performance of a parties, obligation shall not be a basis of force majeure.
Force Majeure shall not be applicable to Tenant's obligation to pay Rent
hereunder as and when it is due and payable.

        Section 31.06. Captions. The article and section headings contained in
this Lease are for convenience only and shall not enlarge or limit the scope or
meaning of the provisions hereof. Words of any gender used in this Lease shall
include any other gender, and words in the singular number shall be held to
include the plural, unless the context otherwise requires.

        Section 31.07. Benefit and Burden. If there be more than one Tenant, the
obligations hereunder imposed upon Tenant shall be joint and several, and all
agreements and covenants herein contained shall be binding upon their respective
heirs, personal representatives, successors, and, to the extent permitted under
this Lease, assigns of the parties hereto. If there be more than one Landlord,
the obligations hereunder imposed upon Landlord shall be joint and several, and
all agreements and covenants herein contained shall be binding upon respective
heirs, personal representatives, successors, and assigns.

        Section 31.08. No Representations by Landlord. Neither Landlord nor
Landlord's agents or brokers have made any representations or promises with
respect to the Premises or the Building except as herein expressly set forth and
all reliance with respect to any representations or promises is based solely on
those contained herein. No rights, easements, or licenses are acquired by Tenant
under this Lease by implication or otherwise except as expressly set forth in
this Lease.

        Section 31.09. Entire Agreement. This Lease sets forth the entire
agreement between the parties and cancels all prior negotiations, arrangements,
brochures, agreements, and understandings, if any, between Landlord and Tenant
regarding the subject matter of this Lease. No amendment or modification of this
Lease shall be binding or valid unless expressed in a writing executed by both
parties hereto.

                                      -46-
<PAGE>

        Section 31.10. No Offer. The submission of this Lease to Tenant shall
not be construed as an offer, nor shall Tenant have any rights with respect
thereto unless Landlord executes a copy of this Lease and delivers the same to
Tenant.

        Section 31.11. Authority. If Tenant signs as a corporation, each of the
persons executing this Lease on behalf of Tenant represents and warrants that
Tenant is a duly organized and existing corporation, that Tenant has been and is
qualified to do business in the Commonwealth of Virginia, that the corporation
has full right and authority to enter into this Lease, and that all persons
signing on behalf of the corporation were authorized to do so by appropriate
corporate actions. If Tenant signs as a partnership, trust, or other legal
entity, each of the persons executing this Lease on behalf of Tenant represents
and warrants that Tenant has complied with all applicable laws, rules, and
governmental regulations relative to its right to do business in the
Commonwealth of Virginia, that such entity has the full right and authority to
enter into this Lease, and that all persons signing on behalf of the Tenant were
authorized to do so by any and all necessary or appropriate partnership, trust,
or other actions.

        If Landlord signs as a corporation, each of the persons executing this
Lease on behalf of Landlord represents and warrants that Landlord is a duly
organized and existing corporation, that Landlord has been and is qualified to
do business in the Commonwealth of Virginia, that the corporation has full right
and authority to enter into this Lease, and that all persons signing on behalf
of the corporation were authorized to do so by appropriate corporate actions. If
Landlord signs as a partnership, trust, or other legal entity, each of the
persons executing this Lease on behalf of Landlord represents and warrants that
Landlord has complied with all applicable laws, rules, and governmental
regulations relative to its right to do business in the Commonwealth of
Virginia, that such entity has the full right and authority to enter into this
Lease, and that all persons signing on behalf of the Landlord were authorized to
do so by any and all necessary or appropriate partnership, trust, or other
actions.

        Section 31.12. Changes Requested by Lender. If, in connection with
obtaining financing for the Building, any lender shall request reasonable
modifications in this Lease as a condition for such financing, Tenant will not
unreasonably withhold, delay, or defer its consent thereto, provided that such
modifications do not increase the obligations of Tenant hereunder or diminish
Tenant's rights hereunder or materially adversely affect either the leasehold
interest hereby created or Tenant's use and enjoyment of the Premises.

        Section 31.13. Governing Law and Construction. This Lease shall be
governed by and construed under the laws of the Commonwealth of Virginia.
Printed parts of this Lease shall be as binding on a parties hereto as other
parts hereof. Parts of this Lease which are written or typewritten shall have no
greater force or effect than, and shall not control, parts which are printed,
but all parts shall be given equal effect. Tenant declares that Tenant has read
and understands all parts of this Lease, including all printed parts thereof.
Should any provision of this Lease require judicial interpretation, it is agreed
that the court interpreting or considering same shall not apply the presumption
that the terms hereof shall be more strictly construed against a party by reason
of the rule or conclusion that a document should be construed more strictly
against the party who itself or through its agent prepared the same, it being
agreed that all parties

                                      -47-
<PAGE>

hereto have participated in the preparation of this Lease and that legal counsel
was consulted by each party hereto before the execution of this Lease.

        Section 31.14. Exhibits. The Exhibits referred to in the Basic Lease
Information are by this reference incorporated fully herein. The term "this
Lease" shall be considered to include all such Exhibits.

        Section 31.15. Landlord's Liability. Anything contained in this Lease to
the contrary notwithstanding, Tenant agrees that Tenant shall look solely to the
estate and property of Landlord in the Building and the land upon which is
situated for the collection of any judgment or other judicial process requiring
the payment of money by Landlord for any default or breach by Landlord under
this Lease, subject, however, to the prior rights of any mortgagee or lessor of
the Building and land upon which the Building is situated. No other assets of
Landlord or any partners, shareholders, or other principals of Landlord shall be
subject to levy, execution or other judicial process for the satisfaction of
Tenant's claim.

        Section 31.16. Use of Name of Building. Tenant shall not, without prior
written consent of Landlord, use the name of the Building for any purpose other
than as the address of the business to be conducted by Tenant on the Premises,
and Tenant shall not-do or permit the doing of anything in connection with
Tenant's business or advertising which in the reasonable judgment of Landlord
may reflect unfavorably on Landlord or the Building or confuse or mislead the
public as to any apparent connection or relationship between Tenant and
Landlord, the Building or the land upon which it is situated.

        Section 31.17. Time of Essence. Time is of the essence in this Lease for
the Landlord and Tenant.

        EXECUTED as of the date first written above.

                       LANDLORD:

                       HYATT PLAZA LIMITED PARTNERSHIP
                       a Virginia limited partnership

                       By:   Fair Lakes Hyatt Limited Partnership, a
                             Virginia limited partnership, its general partner

                             By:   Fair Lakes of Virginia, Inc.
                                   a Virginia corporation

                             By:        [SIG]
                                  -----------

                             Its:
                                  -------------------------------------

                                    TENANT:

                                      -48-
<PAGE>

                                    AMERICAN MANAGEMENT SYSTEMS, INC.
                                    a Delaware corporation

                                    By:   /s/ Frank A. Nicolai
                                    -------------------------------------

                                    Its:  Exec. VP, Secretary & Treasurer
                                    -------------------------------------

[THE FOLLOWING PAGES INCLUDE AS EXHIBIT A FLOOR PLANS OF THE PREMISES.]

                                      -49-
<PAGE>

                              EXHIBIT "B" TO LEASE

                             DATED AUGUST 12, 1993

                                    BETWEEN

                        HYATT PLAZA LIMITED PARTNERSHIP
                   A VIRGINIA LIMITED PARTNERSHIP, (LANDLORD)

                                      AND

                       AMERICAN MANAGEMENT SYSTEMS, INC.
                            A CORPORATION, (TENANT)

                             LEASEHOLD IMPROVEMENTS

        This Exhibit "B" is attached to and made a part of that certain Office
Lease Agreement dated August 12, 1993 (the "Lease"), between HYATT PLAZA LIMITED
PARTNERSHIP ("Landlord"), and AMERICAN MANAGEMENT SYSTEMS, INC. ("Tenant"). The
terms used in this Exhibit that are defined in the Lease shall have the same
meanings as provided in the Lease.

        The purpose of this Exhibit "B" is to set forth the relative rights and
obligations of Landlord and Tenant with respect to the construction and
installation of the initial tenant improvements in the Premises.

A.      DEFINITIONS

        1. "Existing Improvements" means all improvements existing in the
Premises that are more particularly shown on Exhibit B Schedule 1 attached
hereto and incorporated herein.

        2. "Contractor" means the person or firm from time to time selected by
Tenant (pursuant to Paragraph D(3) hereof) to install the Leasehold Improvements
in the Premises.

        3. "Leasehold Improvements" shall mean the aggregate of improvements to
the Premises required by the Approved Plan.

        4. "Tenant's Architect" shall mean the architect or space planner
designated by Tenant and approved by Landlord to prepare the plans and
specifications for the Leasehold Improvements.

        5. "Approved Plan" shall mean the plan for Leasehold Improvements
approved by Landlord and Tenant pursuant to Paragraph D.4. hereof.

B.      GENERAL PROVISIONS

        1. Unless otherwise agreed to in writing by Landlord and Tenant, all
work involved in the design and construction of the Leasehold Improvements shall
be carried out by Tenant, Tenant's Architect and Tenant's Contractor. Each party
shall cooperate with the other to promote the

                                      B-1
<PAGE>

efficient and expeditious completion of such work so that occupancy of each
phase of the Premises may occur when required by Section 3.01 of the Lease.

        2. As of the date of execution of this Lease, the Premises are improved
with the Existing Improvements. All costs associated with the design and
construction of the Premises pursuant to an Approved Plan (including any
demolition to the Existing Improvements) shall be borne by Tenant. As more
particularly set forth in the Lease, Landlord has granted to Tenant a Tenant
Allowance. The Tenant Allowance will be made available to Tenant in monthly
installments. Tenant shall, on a monthly basis, submit to Landlord a statement
setting forth the expenditures made by Tenant during the preceding month with
respect to the Leasehold Improvements. The statement shall be accompanied by
lien waivers from persons paid during the previous month and invoices or
receipts evidencing the amount Tenant has requested Landlord to disburse from
the Tenant Allowance. In such monthly statement, Tenant shall designate which
payments it desires the Landlord to make directly to the billing party. Provided
there is no Event of Default, Landlord shall, within ten (10) days after its
receipt of Tenant's monthly statement, disburse the amount requested. Should the
cost of the Leasehold Improvements exceed the Tenant Allowance, then such excess
shall be paid by Tenant.

C.      DESIGN

        1. Tenant may draw from the Tenant Allowance the cost of all design
services (including all necessary architectural, mechanical and electrical
drawings) required for the Approved Plan.

        2. The design, construction, and installation of the Leasehold
Improvements shall conform to the requirements of applicable building, plumbing,
and electrical codes and the requirements of any authority having jurisdiction
over, or with respect to, such work.

        3. All architectural, mechanical, and electrical plans and
specifications for the Leasehold Improvements must be approved by Landlord. Any
changes in the Approved Plans must also be approved by Landlord. Tenant shall
not be permitted to modify the Building in any way, including but not limited to
the structural, mechanical, and electrical systems, except as approved by
Landlord on the Approved Plan. No alterations by Tenant to the Leasehold
Improvements shall be allowed at any time except as provided in the Lease.

D.      PROCEDURES FOR COMPLETION OF LEASEHOLD IMPROVEMENTS

        The following procedures shall be followed in completing the Leasehold
Improvements.

        1. Prior to commencing construction of any Phase, Tenant shall prepare
and submit to Landlord (for its information) a construction schedule.

        2. Tenant's Architect shall complete working drawings and specifications
and submit the same to Tenant and Landlord approval. Within five (5) business
days after their receipt of such working drawings and specifi-

                                      B-2
<PAGE>

cations, each party shall notify the Tenant's Architect and the other party in
writing as to whether it approves or disapproves such working drawings and
specifications. Should the working drawings and specifications (or parts
thereof) be disapproved by either party, the party, in its notice of
disapproval, shall specify, in reasonable detail, the reasons for its
disapproval. The Tenant's Architect will revise the material and resubmit the
same to Landlord and Tenant for their review and approval. Within five (5) days
after their receipt of the revised material, each party shall notify the other
and the Tenant's Architect in writing as to whether it approves or disapproves
of the revised material. The foregoing process will be repeated (within the time
periods permitted) until such time as both Landlord and Tenant have approved the
working drawings and specifications. Upon approval of the working drawings and
specifications, they will be deemed to be the "Approved Plan" for the phase in
question.

        3. Tenant shall select the general contractor (the "Contractor") who
will perform the Leasehold Improvements. Tenant's selection of the Contractor
shall be subject to Landlord's written approval, which approval shall not be
unreasonably withheld, conditioned or delayed.

E.      RIGHT AND OBLIGATIONS OF LANDLORD

        1. Landlord is permitted to make periodic inspections of the Premises
during construction provided that such inspections are made during reasonable
business hours. Tenant shall not be liable for any damage or injury sustained by
Landlord, or any of Landlord's agents, representatives or employees arising from
Landlord's entry upon the Premises during the construction of the Leasehold
Improvements.

        2. Whenever this Exhibit requires an act by Tenant or a plan, contract
or other construction related document related to the Leasehold Improvements
(the "Construction Document"), to be approved by Landlord, such approval shall
not be unreasonably withheld, conditioned or delayed. The failure of Landlord to
notify Tenant within the time period specified (or if no period is specified
within five (5) business days after Tenant's request for Landlord's approval),
shall constitute Landlord's approval of the Construction Document in question.
Whenever Landlord withholds its approval, Landlord shall provide Tenant with an
explanation of why the approval is being withheld and/or what corrective actions
must be taken so that Landlord may approve the Construction Document in
question. Each party agrees to use good faith efforts to resolve any conflict or
disagreement.

F.      TENANT'S RIGHTS

        In its performance of the Leasehold Improvements, Tenant shall have the
right to take such actions and utilize such facilities as are customarily and
reasonably taken and utilized in the construction of comparable space, subject
to such customary and reasonable restrictions as Landlord may adopt in the
prudent management of the Building. Tenant shall not be charged for the use of
utilities, elevators, loading docks, and similar Building facilities in the
construction of the Leasehold Improvements. No fees of any manner shall be
charged by Landlord for its review of plans and drawings or any supervision or
inspection of the Leasehold Improvements. Landlord shall cause any of its
contractors working in the Building to work in harmony with Tenant and the
Contractor, and Landlord shall not knowingly permit any other contractors to
interfere with the performance of the Leasehold Improvements.

                                      B-3
<PAGE>

        [THE DOCUMENT INCLUDES AS EXHIBIT C A SQUARE FOOT CHART SHOWING VARIOUS
MEASURES OF USABLE SPACE ON EACH FLOOR.]

                                      B-4
<PAGE>

                              EXHIBIT "D" TO LEASE

                             DATED August 12, 1993

                                    BETWEEN

                   HYATT PLAZA LIMITED PARTNERSHIP (Landlord)

                                      and

                       AMERICAN MANAGEMENT SYSTEMS, INC.

                                    (Tenant)

                            CLEANING SPECIFICATIONS

SPECIFICATIONS

AREAS:      The entire premises, including all office space, entrance
            lobby(ies), basement areas, loading platforms), receiving areas,
            landings/steps, public halls, stairways, lavatories, passageways
            and elevator cabs.

PART A - DAILY SERVICES

1.    Toilet Rooms

Rest rooms are to receive complete cleaning and sanitation each night
according to the specifications listed below:

a.      Commodes and Urinals: Commodes shall be washed inside and outside
        including under the lips of each bowl. All seats shall be washed. This
        work shall be performed using an approved disinfectant cleanser. All
        bright metal shall be cleaned and, dry polished. Deodorant blocks shall
        not be used in the urinals.

b.      Washbasins: Washbasins shall be washed inside and outside using an
        approved disinfectant cleanser. All bright metal fixture units and
        plumbing shall be dry polished.

c.      Stall Partitions: All stall partitions shall be damp cleaned using an
        approved disinfectant cleanser. Special attention shall be given to
        urinal partitions.

d.      Entrance Doors: All entrance doors, including stops, jambs, and frames
        shall be cleaned.

e.      Mirrors and Lights: All mirrors and lights immediately above mirrors
        shall be cleaned. Burned out lights shall be reported to the maintenance
        department.

f.      Couches and Chairs: Lather or vinyl couches and chairs shall be damp
        cleaned. All vanity chairs, stools and other furniture shall be treated
        in a like manner.

                                      D-1
<PAGE>

g.      Sanitary Napkin Disposal Containers: All sanitary napkin containers
        shall be emptied, damp cleaned with an approved disinfectant cleanser
        and provided with a new paper bag liner daily.

h.      Installation of Supplies: All supplies such as toilet tissue, paper
        towels, liquid hand soap and bar soap is to be replenished. Insure that
        proper liquid soap is used in dispensers to avoid malfunction (dilute
        with water if necessary to prevent clogging). Periodically, clean
        operating mechanisms and replace liquid soap supply in each dispenser to
        insure proper operation.

i.      Mosaic Floors:    -     Pick up loose paper and trash
                          -     Sweep all floors
                          -     Wet mop floors, using an approved disinfectant
                                cleanser

j.      Walls: Wash/clean walls around soap dispensers, towel containers, and
        light switches as required to maintain clean/bright appearance.

k.      Traps and Floor Drains: Shall be maintained free from odor at all times.
        Periodically, water shall be poured down through these traps/floor
        drains to insure vapor seal.

NOTE:   No harsh or abrasive cleaner shall be used without consulting the
        Property Manager.

2.      Room Cleaning

Executive Offices - Private Offices - Semi-Private Offices -
Reception Areas - Conference Rooms - General Offices

The areas stated above are to receive complete general cleaning daily
according to the specifications listed below.

a.      Wastepaper and Trash Containers: All trash containers shall be emptied
        and returned to original locations. Plastic liners shall be used in
        trash containers and changed as necessary for appearance and sanitation.
        Trash containers shall be periodically washed, for appearance and
        sanitation. All trash collected shall be deposited in exterior bulk
        trash containers provided by the Property Manager. Doors on these
        containers shall be kept closed when not in use. Any spills occurring
        during emptying of trash shall be cleaned up immediately (inside or
        outside), and related stains shall be washed/shampooed as required.

b.      Entrances to Executive Offices and Entrances to of Office Areas on
        Various Floors: All glass doors, plate glass side panels and mirrors,
        including metal frames, stops, jambs shall be cleaned as necessary.

c.      Ash Trays: All ash trays shall be emptied. Ash trays shall then be wiped
        clean with a damp cloth to remove stains and odors.

                                      D-2
<PAGE>

d.      Desks and Chairs: Wood desks shall be thoroughly dusted with a treated
        dust cloth and oiled/waxed as required. Metal desks shall be damp wiped
        as necessary to remove spots and stains, including front and side
        vertical surfaces. All glass desk tops will be damp cleaned. Papers on
        desks shall not be disturbed. All chairs shall be dusted or vacuumed
        from top to bottom, as required.

e.      File and Storage Cabinets: All file and storage cabinets shall be
        thoroughly dusted with a treated dust cloth. Cabinets lined in a row
        shall be dusted along the horizontal and vertical surface of each
        cabinet. Spill stains shall be damp cleaned when required.

f.      Tables and Lamps: Tables shall be treated in a like manner as desks.
        Lamps shall be dusted thoroughly, using a treated dust cloth. When
        dusting lamp shades, be certain that cloth is not laden with dust. Cloth
        lamp shades shall be vacuumed with a soft brush type tool.

g.      Hand Dust/Clean the following using a treated dust cloth:

        -  Window Sills
        -  Pictures and Frames
        -  Counters
        -  Radiator and Fan Coil Unit enclosures (damp clean as required)
        -  Ledges and Shelves under six feet
        -  Doors, Jambs and Stops (particularly along top/horizontal surface)
        -  Pushplates and Kickplates
        -  Coat rack and trees
        -  Telephones, all types including office and telephones in booths
        -  Panel boxes, Fire extinguishers and cabinets, and fire hose
           cabinets/enclosures

h.      Vinyl (Resilient) Tile Floors: All resilient tile floors shall be dusted
        with a treated dust mop. All spillage will be removed, including damp
        mop cleaning when required. (Spray buff floor, using a commercial floor
        polishing machine, synthetic fiber pad and an approved acrylic polymer
        finish as required to maintain gloss).

i.      Carpets: All carpets shall be thoroughly vacuumed. Special attention
        will be paid to all spills, spots and adherents for removal. Spot clean
        carpeting as required.

j.      Glass Partitions: All glass partitions will be washed to remove
        fingermarks and smudges.

3.      Other Cleanable Areas

Main Entrance Lobby - Elevators - Corridors - Snack Bars Stairways, Landings,
Loading Platforms, and Receiving Rooms

The areas listed above are to receive complete daily cleaning as prescribed in
paragraphs A I and 2 above and specialty cleaning according to the
specifications listed below.

                                      D-3
<PAGE>

a.      Main Entrance Lobby: All hard surface floors shall be thoroughly cleaned
        and non-slip floor finish applied as necessary. (Spray buff floor, using
        a commercial floor polishing machine, synthetic fiber pad and an
        approved acrylic polymer finish as required to maintain gloss). All
        entrance door glass shall be cleaned. Area mats shall be removed and
        thoroughly cleaned and returned to their original location. Carpet areas
        shall be vacuumed and spot cleaned as necessary.

b.      Elevators: Interior walls and ceilings shall be dusted with a treated
        dust cloth and spot cleaned as required. All carpets shall be vacuumed
        and stains removed when possible. Telephone boxes shall be checked and
        cleaned of any trash/ashes, etc.

c.      Corridors/Snack Bars:

        (1)     Carpeted areas shall be vacuumed and all stains removed when
                possible. Resilient flooring shall be swept and damp mopped to
                remove spillage. (Spray buff floor, using a commercial floor
                polishing machine, synthetic fiber pad and an approved acrylic
                polymer finish as required to maintain gloss).

        (2)     All refuse, trash and garbage from snack bars and vending
                machine areas shall be collected and removed from the building.
                Cans used for collection of food remnants shall be periodically
                washed inside and out.

d.      Water Fountains: To insure a clean, health condition at the water
        fountains, the dispensing area shall be washed, cleaned and polished.

e.      Stairways: Stair landings and steps shall be swept or vacuumed. Hand
        railing, ledges, grilles, fire apparatus and doors shall be dusted.
        Spills shall be wiped up daily. Spray buff resilient flooring as
        required to maintain gloss.

f.      Outside Entrances: Landings and steps shall be swept. Both sides of
        entrance glass shall be cleaned. Kick plates and push bars shall be
        cleaned and polished.

g.      Loading Platforms/Receiving Rooms: Loading dock areas, platforms and
        receiving rooms shall be swept daily and damp mopped as required.

PART B - WEEKLY SERVICES

1.      Toilet Rooms

        Damp clean and dry polish tile walls.

2.      Room Cleaning

        a.      Vertical Surfaces:

                (1)     Wood wall paneling in Executive Offices shall be dusted
                        using a treated dust cloth.

                                      D-4
<PAGE>

          (2)   Dust vertical surfaces of cabinets, files, etc.

          (3)   All woodwork, doors, walls (including stairwells (,shall be
                spot cleaned to remove smudges/spills etc.

        b.      Other

                (1)     Air conditioning return air grills shall be cleaned
                        (vacuumed if necessary).

                (2)     Vacuum all upholstered furniture and clean any leather
                        furniture with a treated cloth.

3.      Other Cleanable Areas

        Stairways and Landings: All stairways and landings shall be damp mopped
weekly. Dust light fixtures and exposed pipes in stairwells.

PART C - MONTHLY SERVICES

1.      Toilet Rooms

        Dust all high areas and vacuum exhaust grills.

2.      Rooms Cleaning

        a.      Vertical surfaces and under surfaces (knee wells, chair rungs,
                table legs, etc.,) shall be thoroughly dusted and all glass in
                doors, partitions, pictures, and bookcases shall be damp-wiped.
                Dust walls and horizontal surfaces over six feet high.

        b.      Venetian Blinds: Venetian blinds will be dusted in place with a
                treated dust cloth or venetian blind tool.

3.      Other Cleanable Areas

        Elevators: Carpet shall be lifted where appropriate, and flooring swept
and damp mopped.

                                      D-5

<PAGE>

                              EXHIBIT "E" TO LEASE

                             DATED August 12, 1993

                                    BETWEEN

                        HYATT PLAZA LIMITED PARTNERSHIP
                                   (Landlord)

                                      and

                      AMERICAN MANAGEMENT SYSTEMS, INC.
                                    (Tenant)

                              HVAC SPECIFICATIONS

      The Building HVAC system consists of floor-by-floor variable air volume
air handling units.  The typical floor unit provides nominal cooling capacity
of approximately 78 tons.  The air handling units are served by two cooling
towers with a total nominal tonnage of 1,120.  There is a spare capacity in
the condenser water system of approximately 300 tons to more than handle any
supplemental cooling that may be required within the building for special
areas, such as computer rooms or training labs.

      The air is distributed throughout each floor through VAV boxes with
maximum perimeter zones of 1,600 CFM and maximum interior zones of 1,800 CFM.
Heat is provided through electric reheat coils in the VAV boxes, which is
supplemented in certain areas by baseboard heat as well.

      The Building is controlled by the EMS which is designed to turn
equipment off and on in the most energy and cost efficient manner.  The system
also provides for after hours usage by each tenant through an access code that
can be implemented via a touch tone phone.

      Subject to any limitations imposed by governmental authorities having
jurisdiction thereover, the HVAC equipment shall maintain an indoor temperature
of 76 degrees FDB in the summer, so long as the Washington National Airport
outdoor temperature is below 93 degrees FDB and 76 degrees FWB, and of 70
degrees FDB in the winter, so long as the Washington National Airport outdoor
temperature is above 14 degrees FDB.

      The Building system also contains toilet exhaust, general exhaust, smoke
exhaust and elevator and stairwell pressurization systems to meet local fire
codes.

                                      E-1

<PAGE>

                              EXHIBIT "F" TO LEASE

                             DATED August 12, 1993

                                    BETWEEN

                        HYATT PLAZA LIMITED PARTNERSHIP
                                   (Landlord)

                                      and

                      AMERICAN MANAGEMENT SYSTEMS, INC.
                                    (Tenant)

                            BARRIER REMOVAL PROGRAM

<TABLE>
<CAPTION>
- -------------------------------------------------------------------------------
                                                              PLANNED
  ELEMENT               BARRIER              LOCATION       CORRECTIONS
- -------------------------------------------------------------------------------
<S>         <C>                           <C>           <C>
    2.0      Insufficient amount and/or    Parking Lot  At next planned lot
             style of accessible parking                resurfacing/restriping
             spaces
- -------------------------------------------------------------------------------

    3.0      Curb ramp needs detectable    East         Footnote 1
             warnings                      Entrance
- -------------------------------------------------------------------------------

    4.0      Inaccessible entrance needs   West         Footnote 1
             directional signage           Entrance
- -------------------------------------------------------------------------------

    8.0      Floor buttons need braille    All Cabs     Footnote 1
             designations
- -------------------------------------------------------------------------------

    10.0     Door closers do not meet ADA  Rest Rooms,  In process during
             requirements for maximum      Corridor     1993
             opening force                 Doors
- -------------------------------------------------------------------------------

    12.3     Urinals mounted above         All Rest     Footnote 1
             maximum height (24" vs. 17")  Rooms
- -------------------------------------------------------------------------------

    15.0     No AV devices in rest rooms   All Rest     Footnote 1
                                           Rooms
- -------------------------------------------------------------------------------
</TABLE>

                                      F-1

<PAGE>

<TABLE>
<CAPTION>
- ----------------------------------------------------------------------------
                                                              PLANNED
  ELEMENT               BARRIER              LOCATION       CORRECTIONS
- ----------------------------------------------------------------------------
<S>         <C>                           <C>           <C>
    17.0     Public telephone needs        First Floor  At next scheduled
             volume controls and signage   Corridor     replacement of
             per ADA standard                           wall finishes in
                                                        this area
            ----------------------------------------------------------------
             Public telephone mounted      First Floor  At next scheduled
             above maximum allowable       Corridor     replacement of
             height                                     wall finishes in
                                                        this area
- ----------------------------------------------------------------------------
</TABLE>

Footnote 1: All items with this footnote are being remedied gradually, taking
            into consideration priority of barrier as well operational and
            budget considerations.  It is the intent to have all these
            barriers eliminated by not later than 1995.

                                      F-2

<PAGE>

                              EXHIBIT "G" TO LEASE

                             DATED August 12, 1993

                                    BETWEEN

                        HYATT PLAZA LIMITED PARTNERSHIP
                                   (Landlord)

                                      and

                      AMERICAN MANAGEMENT SYSTEMS, INC.
                                    (Tenant)

                             RULES AND REGULATIONS

      This Exhibit "G" is attached to and made a part of that Office Lease
Agreement dated August 12, 1993 (the "Lease"), between HYATT PLAZA LIMITED
PARTNERSHIP ("Landlord"), and AMERICAN MANAGEMENT SYSTEMS, INC. ("Tenant").
Unless the context otherwise requires the terms used in this Exhibit that are
defined in the Lease shall have the same meanings as provided in the Lease.

     The following rules and regulations have been formulated for the safety
and well-being of all tenants of the Building and to ensure compliance with
governmental and other requirements.  Any continuing violation of these rules
and regulations by Tenant shall constitute a Default by Tenant under the Lease.

      Landlord may, upon request of any Tenant, waive compliance by such
Tenant with any of the following rules and regulations, provided (i) no waiver
shall be effective unless signed by Landlord; (ii) any such waiver shall not
relieve such Tenant from the obligation to comply with such rule or regulation
in the future unless otherwise agreed to by Landlord; (iii) no waiver granted
to any Tenant shall relieve any other tenant from the obligation of complying
with these rules and regulations, unless such other tenant has received a
similar written waiver from Landlord; and (iv) any such waiver by Landlord
shall not relieve Tenant from any liability to Landlord for any loss or damage
occasioned as a result of Tenant's failure to comply with any rule or
regulation.

      1.  Sidewalks, plaza areas, entrances, courts, elevators, stairways,
corridors and all other public areas of the Building shall not be obstructed or
encumbered by any tenant or used for any purpose other than ingress and egress
to and from the premises of such tenant.

      2.  No awnings or other projections shall be attached to the outside wall
or windows of the Building. No curtains, blinds, shades, or screens (other than
those furnished as part of the

                                      G-1
<PAGE>

Leasehold Improvements or approved by Landlord as part of an Alteration) shall
be attached to or hung in, or used in connection with, any window or door of the
premises of any tenant.

      3.  Except as otherwise permitted by Sections 24.01, 24.02 and 24.04 of
the Lease, no showcases or other articles shall be put in front of or affixed to
any part of the exterior of the Building, nor placed in the corridor, or other
public areas of the Building.

      4.  Plumbing fixtures and appliances shall be used only for the purposes
for which they were constructed, and no sweepings, rubbish, rags, or other
substances (including, without limitation, coffee grounds) shall be thrown
therein. The cost of repairing any stoppage or damage resulting from misuse of
such fixtures by a tenant or such tenant's servants, employees, agents,
visitors, or licensees, shall be paid by such tenant.

      5.  No tenant shall bring or keep, or permit to be brought or kept, any
inflammable, combustible, or explosive fluid, materials, chemical, or substance
in or about its premises; however, substances used in modern offices may be
brought into and stored (in reasonable quantities) in the Premises.

      6.  Except for paintings or other typical wall hangings, no tenant shall
mark, paint, drill into, or in any way deface, any part of the Building or its
premises. No boring, cutting, or stringing of wires shall be permitted unless
approved as part of an Approved Plan.

      7.  No cooking shall be done or permitted in the Building by any tenant,
except for that which is consistent with an employee kitchen within the
premises. No tenant shall cause or permit any unusual or objectionable odors to
emanate from its premises.

      8.  Neither the whole nor any part of the premises of any tenant shall be
used for manufacturing, for the storage of. merchandise, or for the sale or
exchange of merchandise, goods, or property of any kind.

      9.  Tenants shall not construct, maintain, use, or operate within their
respective premises any electrical device, wiring, or apparatus in connection
with a loud-speaker system or other sound system, except as reasonably required
as part of a communication system approved prior to the installation thereof by
Landlord. No such loud-speaker system shall be constructed, maintained, used or
operated outside of the premises.

      10. No tenant shall make, or permit to be made, any unseemly or disturbing
noises or disturb or interfere with other tenants or occupants of the Building
or neighboring buildings whether by the use of any musical instrument, radio,
television, or other audio device, whistling, singing, or in any other way.
Nothing shall be thrown out of any doors, windows, or any passageways.

      11. Except as permitted by the Lease, no additional locks or bolts of any
kind shall be placed upon any of the doors or windows by and tenant, nor shall
any changes be made in any existing locks or the locking mechanisms therein,
without landlord's approval. The doors leading to the corridors or main halls
shall be kept closed during business hours except as they may

                                      G-2
<PAGE>

be used for ingress or egress. Each tenant shall, upon the termination of its
tenancy, restore to Landlord all keys of offices and storage and toilet rooms
either furnished to, or otherwise procured by, such tenant. In the event of the
loss of any keys so furnished, such tenant shall pay to Landlord the replacement
cost thereof.

      12. The normal hours of operation of the Building shall be 7:00 a.m. to 6
p.m. Monday through Friday, and 8 a.m. to 1 p.m. on Saturdays, customary legal
holidays excluded.

      13. No tenant shall use or occupy or permit any portion of its premises to
be used or occupied as an employment bureau or for the storage, manufacture, or
sale of liquor, narcotics, or drugs. Tenants may, however, have small quantities
of liquor or beer used for entertaining purposes. No tenant shall engage or pay
any employees in the Building, except those actually working for such tenant in
the Building, nor advertise for laborers giving an address at the Building.

      14. Landlord reserves the right to exclude from the Building at all times
any person who is not known or does not properly identify himself to the
Building management or watchman on duty, Landlord may at its option, require all
persons admitted to or leaving the Building between the hours of 6 p.m. and 7:00
a.m., Monday through Friday, and at any hour on Saturdays, Sundays, and legal
holidays, to register. Each Tenant shall be responsible for all persons for whom
it authorizes entry into the Building, and shall be liable to Landlord for all
acts or omissions of such persons.

      15. Each tenant, before closing and leaving its premises at any time,
shall lock all entrance doors and turn off all lights and electrical appliances.

      16. No premises shall be used, or permitted to be used, for lodging or
sleeping or for any immoral or illegal purpose.

      17. Landlord's employees shall not perform, and shall not be requested by
any tenant to perform, any work outside of their regular duties, unless under
specific instructions from the office of Landlord. The requirements of tenants
will be attended to only upon application to Landlord, and any such special
requirements shall be billed to tenants (and paid when the next installment of
rent is due) in accordance with the schedule of charges maintained by Landlord
from time to time or at such charge as is agreed upon in advance by Landlord and
such tenant.

      18. Canvassing, soliciting, and peddling in the Building are prohibited,
and each tenant shall cooperate in seeking their prevention.

      19. Except for trained animals assisting persons with disabilities, no
animals of any kind shall be brought into or kept about the Building by any
tenant.

      20. No vending machines for commercial or public use shall be permitted to
be placed or installed in any part of the Building by any Tenant. Tenant may
have vending machines in kitchen or other non-public areas of the Premises
and/or employee kitchen areas so long as (i) such machines are not available for
use by the general public; (ii) Landlord has approved such

                                      G-3
<PAGE>

machines and (iii) the machines are not visible to the exterior of the Premises
or the Building. Landlord reserves the right to place or install vending
machines in any of the public areas of the Building.

      21. No plumbing or electrical fixtures shall be installed by any Tenant
without the written consent of Landlord.

      22. Bicycles, motorcycles, or any other type of vehicle shall not be
brought into the lobby or elevators of the Building or into the premises of any
tenant.

      23. Landlord has the right to evacuate the Building in event of emergency
or catastrophe.

      24. Landlord reserves the right to rescind any of these Rules and
Regulations and make such other and further rules and regulations as in the
judgment of Landlord shall from time to time be needed for the safety,
protection, care, and cleanliness of the Building, the operation thereof, the
preservation of good order therein, and the protection and comfort of its
tenants, their agents, employees, and invitees, which Rules and Regulation when
made and notice thereof given to a Tenant shall be binding upon him in like
manner as if originally herein prescribed.

                                      G-4
<PAGE>

                              EXHIBIT "H" TO LEASE

                             DATED August 12, 1993

                                    BETWEEN

                        HYATT PLAZA LIMITED PARTNERSHIP
                                   (Landlord)

                                      and

                      AMERICAN MANAGEMENT SYSTEMS, INC.
                                    (Tenant)

                         SUBORDINATION, NON-DISTURBANCE
                            AND ATTORNMENT AGREEMENT

        THIS AGREEMENT is dated the _____ day of _____________, 19__, and is
made between THE AETNA CASUALTY AND SURETY COMPANY or one or more of its
affiliates or designees ("Mortgagee"), and _________________________________
________ ("Tenant").

                                   RECITALS:

        (a)     Tenant has entered into a certain lease ("Lease") dated
_________________ with _______________________________________ as lessor
("Landlord"), covering certain premises known as ____________________________
_____________ and located in ________________________________________________
___ (the "Demised Premises"); and

        (b)     Mortgagee has agreed to make a mortgage loan in the amount of
___________________________________ Dollars ($________) (the "Mortgage") to the
Landlord, secured by the Demised Premises, and the parties desire to set forth
their agreement herein.

        NOW, THEREFORE, in consideration of the Demised Premises and of the sum
of ONE DOLLAR ($1.00) by each party in hand paid to the other, the receipt of
which is hereby acknowledged, the parties hereby agree as follows:

        1.      Said Lease is and shall be subject and subordinate to the
Mortgage insofar as it affects the real property of which the Demised Premises
for a part, and to all renewals, modifications, consolidations, replacements and
extensions thereof, to the full extent of amounts secured thereby and interest
thereon.

        2.      Tenant agrees that it will attorn to and recognize any purchaser
at a foreclosure sale under the Mortgage, any transferee who acquires the
Demised Premises by deed in lieu of foreclosure, and the successors and assigns
of such purchaser(s), as its landlord for the unexpired

                                      H-1
<PAGE>

balance (and any extensions, if exercised) of the term of said Lease upon the
same terms and conditions set forth in said Lease.

        3.      If it becomes necessary to foreclose the Mortgage, Mortgagee
will not terminate said lease nor join Tenant in summary or foreclosure
proceedings so long as Tenant is not in default under any of the terms,
covenants, or conditions of said Lease.

        4.      If Mortgagee succeeds to the interest of Landlord under the
Lease, Mortgagee shall not be:

                a.     liable for any act or omission of any prior landlord
(including Landlord); or

                b.     liable for the return of any security deposit; or

                c.     subject to any offsets or defenses which Tenant might
have against any prior landlord (including Landlord); or

                d.      bound by any rent or additional rent which Tenant might
have paid for more than the current month to any prior landlord (including
Landlord); or

                e.      bound by any amendment or modification of the Lease made
without its consent.

        5.      This Agreement shall be binding upon and shall inure to the
benefit of the parties hereto and their successors and assigns.

        6.      Tenant agrees to give Mortgagee, by registered mail, a copy of
any notice of default served upon the Landlord, provided that prior to such
notice Tenant has been notified in writing (by way of Notice of Assignment of
Rents and Leases, or otherwise), of the address of such Mortgagee. Tenant
further agrees that if Landlord shall have failed to cure such default within
the time provided for in this Lease, then the Mortgagee shall have an additional
sixty (60) days within which to cure such default or if such default cannot be
cured within that time, then such additional time as may be necessary to cure
such default shall be granted if within such sixty (60) days Mortgagee has
commenced and is diligently pursuing the remedies necessary to cure such default
(including, but not limited to, commencement of foreclosure proceedings, if
necessary to effect such cure), in which event the Lease shall not be terminated
while such remedies are being so diligently pursued.

                                      H-2

<PAGE>

        IN WITNESS WHEREOF, the parties hereto have executed these presents as
of the day and year first above written.

                                    Mortgagee:
- ---------------------------------              -----------------------------
Date
                                    By:
                                        ------------------------------------
                                        Its:

                                    Address:   c/o AEtna Realty Investors, Inc.
                                               242 Trumbull
                                               Hartford, CT  06156

                                    Tenant:
- ---------------------------------              -----------------------------
Date
                                    By:
                                        ------------------------------------
                                        Its:

                                      H-3

<PAGE>
                   FIRST AMENDMENT TO OFFICE LEASE AGREEMENT

         THIS FIRST AMENDMENT TO OFFICE LEASE AGREEMENT (the "First Amendment")
is made and entered into this day ___ of _________, 1994 (the "Effective
Date"), by and between HYATT PLAZA LIMITED PARTNERSHIP, a Virginia limited
partnership ("Landlord"), and AMERICAN MANAGEMENT SYSTEMS, INC., a Delaware
corporation ("Tenant"), with reference to the following:

                                   RECITALS:

         A.      Pursuant to an Office Lease Agreement dated August 12, 1993,
by and between Landlord and Tenant (the "Lease"), Landlord has leased to Tenant
certain premises located at 12701 Fair Lakes Circle, Fairfax, Virginia, as more
particularly described therein.  All capitalized terms used herein, unless
specifically defined, shall have the same meaning and definition as used in the
Lease.

         B.      Landlord and Tenant have agreed to amend the certain terms and
provisions of the Lease as hereinafter set forth.

                 NOW, THEREFORE, for good and valuable consideration, the
receipt and sufficiency of which is hereby acknowledged, Landlord and Tenant
agree as follows:

                 1. Under Tenant's Right of First Refusal option, Landlord and
Tenant have agreed to expand the Premises to include an additional 7,926 square
feet of Rentable Area located on the ninth (9th) floor of the Building (the
"Additional Space"), as more particularly shown on Exhibit "A" attached hereto
and made a part hereof by this reference.  Base Rent for the Additional Space
("Additional Space Base Rent") shall be at the rate of $16.50 per square foot
of Rentable Area, or the sum of $130,779.00 per year ($10,898.25 per month),
adjusted as hereinafter set forth.  Tenant shall lease the Additional Space in
its "as is" and "where as" condition, and Landlord shall have no obligation to
make any improvements as a condition of Tenant's acceptance thereof.  Tenant's
lease of the Additional Space shall commence on May 1, 1995 (the "Additional
Space Commencement Date") and shall terminate on April 30, 2000 (the
"Additional Space Expiration
<PAGE>
Date").  Provided, however, that Tenant shall have the right to commence
renovation of the Additional Space prior to the Additional Space Commencement
Date with Landlord's prior written approval.  Any entry upon the Additional
Space prior to the Additional Space Commencement Date shall be subject to all
of the terms and conditions of the Lease, as amended; however, Tenant's
obligations to pay Additional Space Rent hereunder shall commence on the
Additional Space Commencement Date.  Tenant's renovation of the Additional
Space shall be at Tenant's sole expense, and in accordance with the terms and
provisions of Exhibit "B" to the Lease.  On or before the Additional Space
Expiration Date, Tenant  shall surrender possession of the Premises to Landlord
in accordance with the terms of the Lease.

         2.  Commencing on January 1, 1996 and thereafter throughout the
Additional SpaceTerm (as hereinafter defined) Tenant shall pay on a monthly
basis, without demand, as Additional Rent for the Additional Space, Tenant's
Proportionate Share of the amount by which Operating Expenses exceed the Base
Operating Expenses.  The Base Year with respect to the Additional Space shall
be 1995.

         3.      (a) As used in the following paragraphs, the following terms
shall be deemed to refer to, and shall have the following meanings:

                          (1)     Consumer Price Index or CPI: The Consumer
Price Index for All Urban Consumers (CPI-U) for Washington,D.C.-Md.-Va.
All Items(1982-84=100),published by the Bureau of Labor Statistics, United
States Department of Labor.

                          (2)     Base CPI: The most recently published
Consumer Price Index as of the last day of the month immediately preceding the
Additional Space Commencement Date.

                          (3)     CPI Adjustment Factor: Thirty percent (30%).

                 (b)      During the Additional Space Term, the Additional
Space Base Rent shall be adjusted, pursuant to the terms of this Paragraph 2,
on the first day of January of each calendar year after the Additional Space
Commencement Date and on the first day of January annually thereafter during
the term of this First Amendment.  The dates described in this Paragraph 2 for
computing the adjustment of Additional Space Base Rent are hereinafter
sometimes referred to
<PAGE>
collectively as "Rental Adjustment Dates" and singularly as a "Rental
Adjustment Date".  All adjustments to Additional Space Base Rent required by
this Paragraph 2 shall be made as follows:

                          (1)The Base CPI shall be subtracted from the CPI
for the month immediately preceding a Rental Adjustment Date to determine the
changes in the CPI for such period.

                          (2)The number computed in (1) above shall be
divided by the Base CPI to yield a percentage of increase in the CPI.

                          (3)The percentage of increase computed in (2) above
shall be multiplied by the CPI Adjustment Factor.

                          (4)The Additional Space Base Rent (which amount
shall remain constant for purposes of this calculation) shall be multiplied by
the percentage computed in (3) above.

                          (5)The number computed in (4) above shall be
added to the Additional Space Base Rent set forth in (4) immediately above and
the resulting sum will be adjusted rent (hereinafter the "Additional Space
Adjusted Rent") to be paid by the Tenant to Landlord, in advance, without
demand, in equal monthly installments, on the first day of each calendar month
until the next Rental Adjustment Date.

                 (c)      In no event shall any adjustment made pursuant to
this Paragraph 2 ever result in an increase in the Adjusted Rent by more than
three percent (3%) of the Adjusted Rent in effect immediately prior to the
applicable Rental Adjustment Date, nor shall any adjustment made pursuant to
this Paragraph 2 ever result in a decrease in the Additional Space Adjusted
Rent below  the Additional Space Rent payable and in effect for the preceding
calendar year.  In the event of an adjustment which would otherwise cause a
decrease in the Additional Space Adjusted Rent, the Rent payable hereunder in
effect for the preceding year shall continue in effect until the next Rental
Adjustment Date.  Adjustments to Rent shall be effective on the first day of
January each year.

                 (d)      If (i) a significant change is made in the number or
nature (or both) of items used in determining the CPI, or (ii) the CPI shall be
discontinued for any reason, the Bureau of Labor Statistics shall be requested
to furnish a new index comparable to the CPI, together with
<PAGE>
information which will make possible the conversion to the new index in
computing the adjustment to Base Rent hereunder.  If for any reason the Bureau
of Labor Statistics does not furnish such an index and such information,
Landlord and Tenant shall instead accept and use such other index or comparable
statistics on the cost of living in the Washington, D.C. -Md. -Va.
metropolitan area, that is computed and published by an agency of the United
States or a responsible financial periodical of recognized authority.

         (e) Landlord shall provide Tenant with written notice of each
adjustment pursuant to this Paragraph 2, which notice shall provide the basis
upon which such adjustment has been calculated; provided, however, that if for
any reason Landlord does not notify Tenant of the amount of such adjustment
until after any Rental Adjustment Date, Tenant shall continue to pay the
Additional Space Base Rent or Adjusted Rent, as the case may be, payable prior
to the Rental Adjustment Date, and Tenant, within five (5) days following
Landlord's delivery of written notice of such adjustment, shall pay to Landlord
in a lump sum the amount of any increase in the Additional Space Base Rent
resulting from such adjustment for all months in the existing calendar year
prior to and including the month in which such notice of adjustment is received
and during the remainder of such year Tenant shall pay to Landlord the
Additional Space Adjusted Rent as set forth in such notice.

         4.      Tenant shall have the right to renew and extend the Additional
Space Term (the "Additional Space Term") with respect to the Additional Space
for one (1) Renewal Term (herein so called) upon and subject to the following
terms and conditions:

                 (a)Tenant may extend the Additional Space Term for one (1)
Renewal Term of four (4) years (such Renewal Term commencing on May 1, 2000 and
expiring concurrent with the Lease Term on February 29, 2004) by Tenant's
giving written notice thereof to Landlord no later than twelve (12) months
prior to the expiration of the original Additional Space Term.  If Tenant does
not exercise its rights to a Renewal Term in a timely manner, Tenant's failure
shall conclusively be deemed a waiver of its rights to a Renewal Term.
<PAGE>
                 (b)      The exercise by Tenant of its rights to a Renewal
Term must be made, if at all, by written notice executed by Tenant and
delivered to Landlord on or before the date set forth above.  Once Tenant shall
exercise its rights to a Renewal Tenn, Tenant may not thereafter revoke such
exercise.  Tenant  shall not have the right to exercise a Renewal Tenn if
Tenant is in Default under the Lease, as amended, either at the time Tenant
gives notice of its election or immediately prior to the commencement of the
Renewal Term.

                 (c)      Tenant shall take the Additional Space "as is" for
the Renewal Term and Landlord shall have no obligation to make any improvements
or alterations to the Additional Space.

                 (d)      Base Rent per square foot of Rentable Area of the
Additional Space for the first year of the Renewal Term shall be the current
Base Rent, as adjusted, in effect on May 1, 2000.  In no event shall the
Additional Space Base Rent for the first year of the Additional Space Renewal
Tenn be less than the Additional Space Base Rent in effect immediately prior to
the expiration of the original Additional Space Term.

                 (e)      Subject to subparagraph (e) above, the leasing of the
Additional Space for the Renewal Term shall be upon the same terms and
conditions as are applicable for the original Additional Space Term, and shall
be upon and subject to all of the provisions of the Lease, including, without
limitations the obligation of Tenant to pay Tenant's Additional Rent under the
Lease.

         5.      From and after the Additional Space Commencement Date until
the Additional Space Expiration Date, the following terms used in the Lease
shall have the following ascribed meanings:

                 (a)  Premises: Refers to the Rentable Area demised to Tenant
by the Lease (set forth therein) and to the Additional Space demised to Tenant
by this First Amendment, as more fully described and shown on the floor plan(s)
attached as Exhibit "A" hereto.

                 (b)  Additional space:  7,926 square feet of Rentable Area
located on the ninth (9th) floor of the Building, subject to adjustment
pursuant to Paragraph 2 of this Amendment.
<PAGE>
                 (c)  Additional Space Base Rent: $130,779.00 per year
($10,898.25 per month), based on $16.50 per square foot of Rentable Area of the
Premises, as adjusted.

                 (d)  Additional Space Base Year. 1995.

                 (e)  Tenant's Proportionate Share as to Additional Space:
3.14% subject to adjustment pursuant to Paragraph 2 of this First Amendment.

         6.      Except as expressly modified by this First Amendment, the
Lease remains unchanged and in full force and effect.

                        {Signatures appear on next page}

IN WITNESS WHEREOF, Landlord and Tenant have executed this First Amendment as
of the day and year first above written.

                                   LANDLORD:
                                   ---------

                                   HYATT PLAZA LIMITED PARTNERSHIP,
                                   a Virginia limited partnership

                                   By: Fair Lakes Hyatt Limited Partnership,
                                   a Virginia general partnership, its
                                   general partner

                                   By: Fair Lakes of Virginia, Inc.,
                                   a Virginia corporation

                                   By:
                                      --------------------------------
                                      Name:
                                           ---------------------------
                                      Its:
                                          ----------------------------

                                   TENANT:
                                   -------

                                   AMERICAN MANAGEMENT
                                   SYSTEMS, INC., a Delaware corporation

                                   By:
                                      --------------------------------
                                      Name:
                                           ---------------------------
                                      Its:
                                          ----------------------------
<PAGE>
[THE FOLLOWING PAGE INCLUDES AS EXHIBIT A A FLOOR PLAN OF THE ADDITIONAL SPACE]
<PAGE>
                   SECOND AMENDMENT TO OFFICE LEASE AGREEMENT

         THIS SECOND AMENDMENT TO OFFICE LEASE AGREEMENT (the "Second
Amendment") is made and entered into this 1st day of November, 1994 (the
"Effective Date"), by and between HYATT PLAZA LIMITED PARTNERSHIP, a Virginia
limited partnership ("Landlord"), and AMERICAN MANAGEMENT SYSTEMS, INC., a
Delaware corporation ("Tenant"), with reference to the following:

                                   RECITALS:

         A.      Pursuant to an Office Lease Agreement dated August 12, 1993,
by and between Landlord and Tenant, as amended by that certain First Amendment
to Office Lease Agreement dated August 31, 1994 (collectively, the "Lease"),
Landlord has leased to Tenant certain premises located at 12701 Fair Lakes
Circle, Fairfax, Virginia, as more particularly described therein.  All
capitalized terms used herein, unless specifically defined, shall have the same
meaning and definition as used in the Lease.

         B.      Landlord and Tenant have agreed to amend the certain terms and
provisions of the Lease as hereinafter set forth.

                 NOW, THEREFORE, for good and valuable consideration, the
receipt and sufficiency of which is hereby acknowledged, Landlord and Tenant
agree as follows:

         1.      Under Tenant's Right of First Refusal option, Landlord and
Tenant have agreed to expand the Premises to include an additional 5,175 square
feet of Rentable Area located on the tenth (10th) floor of the Building (the
"Additional Space"), as more particularly shown on Exhibit "A" attached hereto
and made a part hereof by this reference.  Base Rent for the Additional Space
("Additional Space Base Rent") shall be at the rate of $16.50 per square foot
of Rentable Area, or the sum of $85,387.50 per year ($7,115.63 per month),
adjusted as hereinafter set forth.  Tenant shall lease the Additional Space in
its "as is" and "where as" condition, and Landlord shall have no obligation to
make any improvements as a condition of Tenant's acceptance thereof.  Tenant's
lease of the Additional Space shall commence on April 1, 1995 (the "Additional
Space

<PAGE>
Commencement Date") and shall terminate on March 30, 2000 (the "Additional
Space Expiration Date").  Provided, however, that Tenant shall have the right
to commence renovation of the Additional Space prior to the Additional Space
Commencement Date with Landlord's prior written approval.  Any entry upon the
Additional Space prior to the Additional Space Commencement Date shall be
subject to all of the terms and conditions of the Lease, as amended; however,
Tenant's obligations to pay Additional Space Rent hereunder shall commence on
the Additional Space Commencement Date.  Tenant's renovation of the Additional
Space shall be at Tenant's sole expense, and in accordance with the terms and
provisions of Exhibit "B" to the Lease.  On or before the Additional Space
Expiration Date, Tenant shall surrender possession of the Premises to Landlord
in accordance with the terms of the Lease.

         2.      Commencing on January 1, 1996 and thereafter throughout  the
Additional Space Term (as hereinafter defined) Tenant shall pay on a monthly
basis, without demand, as Additional Rent for the Additional Space, Tenant's
Proportionate Share of the amount by which Operating Expenses exceed the Base
Operating Expenses.  The Base Year with respect to the Additional Space shall
be 1995.

         3.      (a) As used in the following paragraphs, the following terms
shall be deemed to refer to, and shall have the following meanings:

                          (1)     Consumer Price Index or CPI: The Consumer
Price Index for All Urban Consumers(CPI-U)for Washington,D.C.-Md.-Va.  All
Items(1982-84=100), published by the Bureau of Labor Statistics, United States
Department of Labor.

                          (2)     Base CPI:  The most recently published
Consumer Price Index as of the last day of the month immediately preceding the
Additional Space Commencement Date.

                          (3)     CPI Adjustment Factor:  Thirty percent (30%).

                 (b)      During the Additional Space Term, the Additional
Space Base Rent shall be adjusted, pursuant to the terms of this Paragraph 2,
on the first day of January of each calendar year after the Additional Space
Commencement Date and on the first day of January annually

<PAGE>
thereafter during the term of this Second Amendment.  The dates described in
this Paragraph 2 for computing the adjustment of Additional Space Base Rent are
hereinafter sometimes referred to collectively as "Rental Adjustment Dates" and
singularly as a "Rental Adjustment Date".  All adjustments to Additional Space
Base Rent required by this Paragraph 2 shall be made as follows:

                          (1)     The Base CPI shall be subtracted from the CPI
for the month immediately preceding a Rental Adjustment Date to determine the
changes in the CPI for such period.

                          (2)     The number computed in (1) above shall be
divided by the Base CPI to yield a percentage of increase in the CPI.

                          (3)     The percentage of increase computed in (2)
above shall be multiplied by the CPI Adjustment Factor.

                          (4)     The Additional Space Base Rent (which amount
shall remain constant for purposes of this calculation) shall be multiplied by
the percentage computed in (3) above.

                          (5)     The number computed in (4) above shall be
added to the Additional Space Base Rent set forth in (4) immediately above and
the resulting sum will be the adjusted rent (hereinafter the "Additional Space
Adjusted Rent") to be paid by the Tenant to Landlord, in advance, without
demand, in equal monthly installments, on the first day of each calendar month
until the next Rental Adjustment Date.

                 (c)      In no event shall any adjustment made pursuant to
this Paragraph 2 ever result in an increase in the Adjusted Rent by more than
three percent (3%) of the Adjusted Rent in effect immediately prior to the
applicable Rental Adjustment Date, nor shall any adjustment made pursuant to
this Paragraph 2 ever result in a decrease in the Additional Space Adjusted
Rent below the Additional Space Rent payable and in effect for the preceding
calendar year.  In the event of an adjustment which would otherwise cause a
decrease in the Additional Space Adjusted Rent, the Rent payable hereunder in
effect for the preceding year shall continue in effect until the next

3
<PAGE>
Rental Adjustment Date.  Adjustments to Rent shall be effective on the first
day of January each year.

                 (d)      If (i) a significant change is made in the number or
nature (or both) of items used in determining the CPI, or (ii) the CPI shall be
discontinued for any reason, the Bureau of Labor Statistics shall be requested
to furnish a new index comparable to the CPI, together with information which
will make possible the conversion to the new index in computing the adjustment
to Base Rent hereunder.  If for any reason the Bureau of Labor Statistics does
not furnish such an index and such information, Landlord and Tenant shall
instead accept and use such other index or comparable statistics on the cost of
living in the Washington, D.C.-Md.-Va. metropolitan area, that is computed and
published by an agency of the United States or a responsible financial
periodical of recognized authority.

                 (e)      Landlord shall provide Tenant with written notice of
each adjustment pursuant to this Paragraph 2, which notice shall provide the
basis upon which such adjustment has been calculated; provided, however, that
if for any reason Landlord does not notify Tenant of the amount of such
adjustment until after any Rental Adjustment Date, Tenant shall continue to pay
the Additional Space Base Rent or Adjusted Rent, as the case may be, payable
prior to the Rental Adjustment Date, and Tenant, within five (5) days following
Landlord's delivery of written notice of such adjustment, shall pay to Landlord
in a lump sum the amount of any increase in the Additional Space Base Rent
resulting from such adjustment for all months in the existing calendar year
prior to and including the month in which such notice of adjustment is received
and during the remainder of such year Tenant shall pay to Landlord the
Additional Space Adjusted Rent as set forth in such notice.

         4.      Tenant shall have the right to renew and extend the Additional
Space Term (the "Additional Space Term") with respect to the Additional Space
for one (1) Renewal Term (herein so called) upon and subject to the following
terms and conditions:

                 (a)      Tenant may extend the Additional Space Term for one
(1) Renewal Term of four (4) years (such Renewal Term commencing on April 1,
2000 and expiring concurrent with the

<PAGE>
Lease Term on February 29, 2004) by Tenant's giving written notice thereof to
Landlord no later than twelve (12) months prior to the expiration of the
original Additional Space Term.  If Tenant does not exercise its rights to a
Renewal Term in a timely manner, Tenant's failure shall conclusively be deemed
a waiver of its rights to a Renewal Term.

                 (b)      The exercise by Tenant of its rights to a Renewal
Term must be made, if at all, by written notice executed by Tenant and
delivered to Landlord on or before the date set forth above.  Once Tenant shall
exercise its rights to a Renewal Term, Tenant may not thereafter revoke such
exercise.  Tenant shall not have the right to exercise a Renewal Term if Tenant
is in Default under the Lease, as amended, either at the time Tenant gives
notice of its election or immediately prior to the  commencement of the Renewal
Term.

                 (c)      Tenant shall take the Additional Space "as is" for
the Renewal Term and Landlord shall have no obligation to make any improvements
or alterations to the Additional Space.

                 (d)      Base Rent per square foot of Rentable Area of the
Additional Space for the first year of the Renewal Term shall be the current
Base Rent, as adjusted, in effect on April 1, 2000.  In no event shall the
Additional Space Base Rent for the first year of the Additional Space Renewal
Term be less than the Additional Space Base Rent in effect immediately prior to
the expiration of the original Additional Space Term.

                 (e)      Subject to subparagraph (e) above, the leasing of the
Additional Space for the Renewal Term shall be upon the same terms and
conditions as are applicable for the original Additional Space Term, and shall
be upon and subject to all of the provisions of the Lease, including, without
limitation, the obligation of Tenant to pay Tenant's Additional Rent under the
Lease.

         5.      From and after the Additional Space Commencement Date until
the Additional Space Expiration Date, the following terms used in the Lease
shall have the following ascribed meanings:

5
<PAGE>
                 (a)      Premises: Refers to the Rentable Area demised to
Tenant by the Lease (set forth therein) and to the Additional Space demised to
Tenant by the First Amendment and the Additional Space demised to Tenant by
this Second Amendment, as more fully described and shown on the floor plan(s)
attached as Exhibit "A" hereto.

                 (b)      Additional Space: 5,175 square, feet of Rentable Area
located on the tenth (10th) floor of the Building, subject to adjustment
pursuant to Paragraph 2 of this Amendment.

                 (c)      Additional Space Base Rent: $85,387.50 per year
($7,115.65 per month), based on $16.50 per square foot of Rentable Area of the
Additional Space as adjusted.

                 (d)      Additional Space Base Year. 1995.

                 (e)      Tenant's Proportionate Share as to Additional Space:
2.05% subject to adjustment pursuant to Paragraph 2 of this Second Amendment.

         6.      Except as expressly modified by this Second Amendment, the
Lease remains unchanged and in full force and effect.

<PAGE>
IN WITNESS WHEREOF, Landlord and Tenant have executed this Second Amendment as
of the day and year first above written.

                           LANDLORD:
                           ---------

                           HYATT PLAZA LIMITED PARTNERSHIP,
                           a Virginia limited partnership

                           By:     Fair Lakes Hyatt Limited Partnership, a
                           Virginia general partnership, its general partner

                           By:     Fair Lakes of Virginia, Inc., a Virginia
                           corporation

                           By:          [SIG]
                             --------------------------------
                           Name:
                                -----------------------------
                           Its:
                               ------------------------------

                           TENANT:
                           -------

                           AMERICAN MANAGEMENT SYSTEMS, INC.,
                           a Delaware corporation

                           By:  /s/ Frank A. Nicolai
                             --------------------------------
                           Name:   Frank A. Nicolai
                                -----------------------------
                           Its:    Executive Vice President,
                               ------------------------------
                                   Secretary and Treasurer
                               ------------------------------

7
<PAGE>
                   THIRD AMENDMENT TO OFFICE LEASE AGREEMENT

THIS THIRD AMENDMENT TO OFFICE LEASE AGREEMENT (this "Third Amendment") is made
and entered into this 2nd day of October 1995 (the "Effective Date"), by and
between HYATT PLAZA LIMITED PARTNERSHIP, a Virginia limited partnership
("Landlord"), and AMERICAN MANAGEMENT SYSTEMS, INC., a Delaware corporation
("Tenant"), with reference to the following:

                                   RECITALS:

         A.      Pursuant to an Office Lease Agreement dated August 12, 1993,
by and between Landlord and Tenant, as amended by that certain (i) First
Amendment to Office Lease Agreement dated August 31, 1994 and (ii) Second
Amendment Office Lease Agreement dated November 1, 1994 (collectively, the
"Lease"), Landlord has leased to Tenant certain premises located at 12701 Fair
Lakes Circle, Fairfax, Virginia, as more particularly described therein.  All
capitalized terms used herein, unless specifically defined, shall have the same
meaning and definition as used in the Lease.

         B.      Landlord and Tenant have agreed to amend the certain terms and
provisions of the Lease as hereinafter set forth.

         NOW, THEREFORE, for good and valuable consideration, the receipt and
sufficiency of which is hereby acknowledged, Landlord and Tenant agree as
follows:

1.       Under Tenant's Right of First Refusal option, Landlord and Tenant have
agreed to expand the Premises to include an additional 5,327 square feet of
Rentable Area located on the third (3rd) floor of the Building (the "Third
Amendment Space"), commonly known as Suite 320, as

<PAGE>
more particularly shown on Exhibit "A" attached hereto and made a part hereof
by this reference.  Base Rent for the Third Amendment Space ("Third Amendment
Space Base Rent") shall be at the rate of $17.00 per square foot of Rentable
Area, or the sum of $90,559.00 per year ($7,546.58 per month), adjusted as
hereinafter set forth.  Tenant shall lease the Third Amendment Space in its "as
is" and "where as" condition, and Landlord shall have no obligation to make any
improvements as a condition of Tenant's acceptance thereof.  Notwithstanding,
Landlord agrees to provide Tenant with a Renovation Allowance of up to $5.00
per rentable square foot in the Third Amendment Space.  Landlord shall
reimburse Tenant for approved improvements to the Third Amendment Space within
thirty (30) days after receipt of invoices from Tenant.  Tenant's lease of
Third Amendment Space shall commence January 1, 1996 (the "Third Amendment
Space Commencement Date") and shall terminate on December 31, 2000 (the "Third
Amendment Space Expiration Date") (the "Third Amendment Space Initial Term").
Provided, however, that Tenant shall have the right to commence renovation of
the Third Amendment Space prior to the Third Amendment Space Commencement Date
and after October 1, 1995 with Landlord's prior written approval.  Any entry
upon the Third Amendment Space prior to the Third Amendment Space Commencement
Date shall be subject to all of the terms and conditions of the Lease, as
amended; however, Tenant's obligations to pay Third Amendment Space Base Rent
and Third Amendment Space Additional  Rent (as hereinafter defined) shall
commence on the Third Amendment Space Commencement Date.  Tenant's renovation
of the Third Amendment Space shall be at Tenant's sole expense, and in
accordance with the terms and provisions of Exhibit "B" to the Lease.  On or
before the Third Amendment Space Expiration Date, Tenant shall surrender
possession of the Premises to Landlord in accordance with the terms of the
Lease.

2.       Commencing on January 1, 1997 and thereafter throughout the Third
Amendment Space Initial Term Tenant shall pay on a monthly basis, without
demand, as Additional Rent for the Third Amendment Space, 2.11% of the amount
by which Operating Expenses exceed the Adjusted Base Operating Expenses.
Adjusted Base Operating Expenses shall, for purposes of this Amendment, refer
to the Operating Expenses incurred during the 1996 calendar

                                       2
<PAGE>
year.  Such payments shall be made in accordance with Section 6.01 of the
Lease.

3.       (a)     As used in the following paragraphs, the following terms shall
be deemed to refer to, and shall have the following meanings:

                 (1)      Consumer Price Index or CPI: The Consumer Price Index
for All Urban Consumers (CPI-U) for Washington, D.C.-Md.-Va. All Items
(1982-84=100), published by the Bureau of Labor Statistics, United States
Department of Labor.

                 (2)      Base CPI: The most recently published Consumer Price
Index as of the last day of the month immediately preceding the Third Amendment
Space Commencement Date.

                 (3)      CPI Adjustment Factor: Thirty percent (30%).

         (b)     During the Third Amendment Space Initial Term, the Third
Amendment Space Base Rent shall be adjusted, pursuant to the terms of this
Paragraph 3, on the first day of January of each calendar year after the Third
Amendment Space Commencement Date and on the first day of January annually
thereafter during the term of this Third Amendment.  The dates described in
this Paragraph 3 for computing the adjustment of Third Amendment Space Base
Rent are hereinafter sometimes referred to collectively as "Rental Adjustment
Dates" and singularly as a "Rental Adjustment Date".  All adjustments to Third
Amendment Space Base Rent required by this Paragraph 3 shall be made as
follows:

                                       3
<PAGE>
                 (1)      The Base CPI shall be subtracted from the CPI for the
month immediately preceding a Rental Adjustment Date to determine the changes
in the CPI for such period.

                 (2)      The number computed in (1) above shall be divided by
the Base CPI to yield a percentage of increase in the CPI.

                 (3)      The percentage of increase computed in (2) above
shall be multiplied by the CPI Adjustment Factor.

                 (4)      The Third Amendment Space Base Rent (which amount
shall remain constant for purposes of this calculation) shall be multiplied by
the percentage computed in (3) above.

                 (5)      The number computed in (4) above shall be added to
the Third Amendment Space Base Rent set forth in (4) immediately above and the
resulting sum will be the adjusted rent (hereinafter the "Third Amendment Space
Adjusted Rent") to be paid by Tenant to Landlord, in advance, without demand,
in equal monthly installments, on the first day of each calendar month until
the next Rental Adjustment Date.

         (c)     In no event shall any adjustment made pursuant to this
Paragraph 3 ever result in an increase in the Third Amendment Space Adjusted
Rent by more than three percent (3%) of the Third Amendment Space Adjusted Rent
in effect immediately prior to the applicable Rental

                                       4
<PAGE>
Adjustment Date, nor shall any  adjustment made pursuant to this Paragraph 3
ever result in a decrease in the Third Amendment Space Adjusted Rent below the
Third Amendment Space Base Rent and Third Amendment Space Additional Rent
payable and in effect for the preceding calendar year.  In the event of an
adjustment which would otherwise cause a decrease in the Third Amendment Space
Adjusted Rent, the Rent payable hereunder in effect for the preceding year
shall continue in effect until the next Rental Adjustment Date.  Adjustments to
Rent shall be effective on the first day of January each year.

         (d)     If (i) a significant change is made in the number or nature
(or both) of items used in determining the CPI, or (ii) the CPI shall be
discontinued for any reason, the Bureau of Labor Statistics shall be requested
to furnish a new index comparable to the CPI, together with information which
will make possible the conversion to the new index in computing the adjustment
to Base Rent hereunder.  If for any reason the Bureau of Labor Statistics does
not furnish such an index and such information, Landlord and Tenant shall
instead accept and use such other index or comparable statistics on the cost of
living in the Washington, D.C. -Md. -Va. metropolitan area, that is computed
and published by an agency of the United States or a responsible financial
periodical of recognized authority.

         (e)     Landlord shall provide Tenant with written notice of each
adjustment pursuant to this Paragraph 2, which notice shall provide the basis
upon which such adjustment has been calculated; provided, however, that if for
any reason Landlord does not notify Tenant of the amount of such adjustment
until after any Rental Adjustment Date, Tenant shall continue

                                       5
<PAGE>
to pay the Third Amendment Space Base Rent or Adjusted Rent, as the case may
be, payable prior to the Rental Adjustment Date, and Tenant, within five (5)
days following Landlord's delivery of written notice of such adjustment, shall
pay to Landlord in a lump sum the amount of any increase in the Third Amendment
Space Base Rent resulting from such adjustment for all months in the existing
calendar year prior to and including the month in which such notice of
adjustment is received and during the remainder of such year Tenant shall pay
to Landlord the Third Amendment Space Adjusted Rent as set forth in such
notice.

4.       Tenant shall have the right to renew and extend the Third Amendment
Space Initial Term (the "Third Amendment Space Renewal Term") with respect to
the Third Amendment Space for one (1) Renewal Term (herein so called) upon and
subject to the following terms and conditions:

         (a)     Tenant may extend the Third Amendment Space Initial Term for
one (1) Renewal Term of five (5) years (such Renewal Term commencing on January
1, 2001 and expiring on December 31, 2005 by Tenant's giving written notice
thereof to Landlord no later, than twelve (12) months prior to the expiration
of the Third Amendment Space Initial Term.  If Tenant does not exercise its
rights to a Renewal Term in a timely manner, Tenant's failure shall
conclusively be deemed a waiver of its rights to a Renewal Term.

         (b)     The exercise by Tenant of its rights to a Renewal Term must be
made, if at all, by written notice executed by Tenant and delivered to Landlord
on or before the date set forth above.  Once Tenant shall exercise its rights
to a Renewal Term, Tenant may not thereafter

                                       6
<PAGE>
revoke such exercise.  Tenant shall not have the right to exercise a Renewal
Term if Tenant is in Default under the Lease, as amended, either at the time
Tenant gives notice of its election or  immediately prior to the commencement
of the Renewal Term.

         (c)     Tenant shall take the Third Amendment Space "as is" for the
Renewal Term and Landlord shall have no obligation to make any improvements or
alterations to the Third Amendment Space.

         (d)     Base Rent per square foot of Rentable Area of the Third
Amendment Space for the first year of the Renewal Term shall be the current
Third Amendment Space Base Rent, as adjusted, in effect on January 1, 2001.  In
no event shall the Third Amendment Space Base Rent for the first year of the
Third Amendment Space Renewal Term be less than the Third Amendment Space Base
Rent, as adjusted, in effect immediately prior to the expiration of the Third
Amendment Space Initial Term.

         (e)     Subject to subparagraph (d) above, the leasing of the Third
Amendment Space for the Renewal Term shall be upon the same terms and
conditions as are applicable for the Third Amendment Space Initial Term, and
shall be upon and subject to all of the provisions of the Lease, including,
without limitation, the obligation of Tenant to pay Tenant's Third Amendment
Space Additional Rent under the Lease.

5.       From and after the Third Amendment Space Commencement Date until the
Third

                                       7
<PAGE>
Amendment Space Expiration Date, the following terms used in the Lease shall
have the following ascribed meanings:

         (a)     Premises:  Refers to the Rentable Area demised to Tenant by
the Lease (set forth therein) and to the space demised to Tenant by the First
Amendment, Second Amendment and the Third Amendment Space demised to Tenant by
this Third Amendment, as more fully described and shown on the floor plan(s)
attached as Exhibit "A" hereto.

         (b)     Third Amendment Space: 5,327 square feet of Rentable Area
located on the third (3rd floor of the Building, subject to adjustment pursuant
to Paragraph 2 of this Third Amendment.

         (c)     Third Amendment Space Renewal Term: Refers to the Third
Amendment Space Renewal Term, if exercised by Tenant pursuant to the terms and
conditions of this Third Amendment.

6.       Except as expressly modified by this Third Amendment, the Lease
remains unchanged and in full force and effect.

         [Signatures to appear on next page.]

                                       8
<PAGE>
IN WITNESS WHEREOF, Landlord and Tenant have executed this Third Amendment as
of the day and year first above written.

                            LANDLORD:
                            ---------

                            HYATT PLAZA LIMITED PARTNERSHIP,
                            a Virginia limited partnership

                            By:      Fair Lakes Hyatt Limited Partnership, a
                                     Virginia general partnership, its general
                                     partner

                            By:      Fair Lakes of Virginia, Inc.,
                                     a Virginia corporation

                            By:   /s/  Milton V. Peterson
                                -------------------------------
                            Name:  Milton V. Peterson
                                 ------------------------------
                            Its:  President
                                 ------------------------------

                            TENANT:
                            -------

                            AMERICAN MANAGEMENT SYSTEMS,
                            INC.,
                            a Delaware corporation

                            By:      /s/  Frank A. Nicolai
                                -----------------------------------
                            Name:    Frank A. Nicolai
                                  --------------------------------
                            Its:  Executive Vice President
                                  -------------------------------
                                  Secretary & Treasurer
                                  -------------------------------

                                       9
<PAGE>

                                   EXHIBIT A

                        THIRD AMENDMENT SPACE FLOOR PLAN

                       [INCLUDES FLOOR PLAN OF PREMISES]

                                       10
<PAGE>
                   FOURTH AMENDMENT TO OFFICE LEASE AGREEMENT

         THIS FOURTH AMENDMENT TO OFFICE LEASE AGREEMENT (this "Fourth
Amendment") is made and entered into as of the 12th day of August, 1996 (the
"Effective Date"), by and between HYATT PLAZA LIMITED PARTNERSHIP, a Virginia
limited partnership ("Landlord"), and AMERICAN MANAGEMENT SYSTEMS, INC., a
Delaware corporation ("Tenant"), with reference to the following:

                                   RECITALS:

         A.      Pursuant to an Office Lease Agreement dated August 12, 1993,
by and between Landlord and Tenant, as amended by that certain (i) First
Amendment to Office Lease Agreement dated August 31, 1994, (ii) Second
Amendment to Office Lease Agreement dated November 1, 1994 and (iii) Third
Amendment to Office Lease Agreement dated October 2, 1995 (collectively, the
"Lease"), Landlord has leased to Tenant certain premises located at 12701 Fair
Lakes Circle, Fairfax, Virginia, as more particularly described therein.  All
capitalized terms used herein, unless specifically defined, shall have the same
meaning and definition as used in the Lease.

         B.      Landlord and Tenant have agreed to amend the certain terms and
provisions of the Lease as hereinafter set forth.

         NOW, THEREFORE, for good and valuable consideration, the receipt and
sufficiency of which is hereby acknowledged, Landlord and Tenant agree as
follows:

         1.      Landlord and Tenant have agreed to expand the Premises to
include an additional 851 square feet of Rentable Area located on the third
(3rd) floor of the Building (the "Fourth Amendment Space"), commonly known as
Suite 365, as more particularly shown on Exhibit "A" attached hereto and made a
part hereof by this reference.  Base Rent for the Fourth Amendment Space
("Fourth Amendment Space Base Rent") shall be as set forth below:

                 (i)      From August 12, 1996 to August 31, 1997, $18.75 per
         square foot of Rentable Area, or the sum of $15,956.25 per year
         ($1,329.69 per month), and

                 (ii)     From September 1, 1997 to August 31, 1998, $19.22 per
         square foot of Rentable Area, or the sum of $16,356.22 per year
         ($1,363.02 per month).

         2.      Tenant shall lease the Fourth Amendment Space in its "as is"
and "where is" condition, and Landlord shall have no obligation to make any
improvements as a condition of Tenant's acceptance thereof.  Tenant's lease of
Fourth Amendment Space shall commence August 12, 1996 (the "Fourth Amendment
Space Commencement Date") and shall terminate August 31, 1998 (the "Fourth
Amendment Space Expiration Date") (the "Fourth Amendment Space Initial

<PAGE>
Term").  On or before the Fourth Amendment Space Expiration Date, Tenant shall
surrender possession of the Premises to Landlord in accordance with the terms
of the Lease.

         3.      Commencing on January 1, 1997 and thereafter throughout the
Fourth Amendment Space Initial Term, Tenant shall pay on a monthly basis,
without demand, as Additional Rent for the Fourth Amendment Space, .34% of the
amount by which Operating Expenses exceed the Adjusted Base Operating Expenses.
Adjusted Base Operating Expenses shall, for purposes of this Amendment, refer
to the Operating Expenses incurred during the 1996 calendar year.  Such
payments shall be made in accordance with Section 6.01 of the Lease and
Paragraph 3 of the Third Amendment to the Lease.

         4.      Tenant shall have the right to renew and extend the Fourth
Amendment Space Initial Term (the "Fourth Amendment Space Renewal Term") with
respect to the Fourth Amendment Space for one (1) Renewal Term (herein so
called) upon and subject to the following terms and conditions:

                 (a)      Tenant may extend the Fourth Amendment Space Initial
Term for one (1) Renewal Term of three (3) years, such Renewal Term commencing
on September 1, 1998 and expiring on August 31, 2001, by Tenant's giving
written notice thereof to Landlord no later than six (6) months prior to the
expiration of the Fourth Amendment Space Initial Term.  If Tenant does not
exercise its rights to a Renewal Term in a timely manner, Tenant's failure
shall conclusively be deemed a waiver of its rights to a Renewal Term.

                 (b)      The exercise by Tenant of its rights to a Renewal
Term must be made, if at all, by written notice executed by Tenant and
delivered to Landlord on or before the date set forth above.  Once Tenant shall
exercise its rights to a Renewal Term, Tenant may not thereafter revoke such
exercise.  Tenant shall not have the right to exercise a Renewal Term if Tenant
is in Default under the Lease, as amended, either at the time Tenant gives
notice of its election or immediately prior to the commencement of the Renewal
Term.

                 (c)      Tenant shall take the Fourth Amendment Space "as is"
for the Renewal Term and Landlord shall have no obligation to make any
improvements or alterations to the Fourth Amendment Space.

                 (d)      Base Rent per square foot of Rentable Area of the
Fourth Amendment Space for the first year of the Renewal Term shall be the
market rate for Fair Lakes as reasonably determined by Landlord for comparable
size space, and for Leases with comparable terms, conditions and concessions.
Such Base Rate shall be adjusted on September 1 of each subsequent year of the
Renewal Term by multiplying the Base Rent in effect on August 31 by 2.5% and
adding the product to the Base Rent then in effect.  The Adjusted Base Rent
shall be in effect until the next adjustment date.

                 (e)      Subject to subparagraph (d) above, the leasing of the
Fourth Amendment Space for the Renewal Term shall be upon the same terms and
conditions as are applicable for the Fourth Amendment Space Initial Term, and
shall be upon and subject to all of the provisions of

                                       2
<PAGE>
the Lease, including, without limitation, the obligation of Tenant to pay
Tenant's Fourth  Amendment Space Additional Rent under the Lease.

         5.      From and after the Fourth Amendment Space Commencement Date
until the Fourth Amendment Space Expiration Date, the following terms used in
the Lease shall have the following ascribed meanings:

                 (a)      Premises: Refers to the Rentable Area demised to
Tenant by the Lease (set forth therein) and to the space demised to Tenant by
the First Amendment, Second Amendment, Third Amendment and Fourth Amendment
Space, demised to Tenant by this Fourth Amendment.

                 (b)      Fourth Amendment Space: 851 square feet of Rentable
Area located on the third (3rd floor of the Building, subject to adjustment
pursuant to Paragraph 2 of this Fourth Amendment.

                 (c)      Fourth Amendment Space Renewal Term: Refers to the
Fourth Amendment Space Renewal Term, if exercised by Tenant pursuant to the
terms and conditions of this Fourth Amendment.

                 (d)      Rentable Area of the Premises:

<TABLE>
                           <S>                                                <C>
                           Original Lease Space                                84,236 square feet
                           First Amendment Space                                7,926 square feet
                           Second Amendment Space                               5,175 square feet
                           Third Amendment Space                                5,327 square feet
                           Fourth Amendment Space                                 851 square feet
                                                                              -------

                           Total------------------------------------          103,515 square feet
</TABLE>

                 (e)      Tenant's Proportionate Share as to the Fourth
Amendment Space: .34%

         Except as expressly modified by this Fourth Amendment, the Lease
remains unchanged and in full force and effect.

                                       3
<PAGE>
         IN WITNESS WHEREOF, Landlord and Tenant have executed this Fourth
Amendment as of the day and year first above written.

                           LANDLORD:
                           ---------

                           HYATT PLAZA LIMITED PARTNERSHIP,
                           a Virginia limited partnership

                           By: Fair Lakes Hyatt Limited Partnership, a
                               Virginia general partnership, its general partner

                           By: Fair Lakes of Virginia, Inc.,
                               a Virginia corporation
                               its general partner

                           By:
                               -----------------------------------
                           Name:
                                ----------------------------------
                           Its:
                               -----------------------------------

                           TENANT:
                           -------

                           AMERICAN MANAGEMENT SYSTEMS, INC.,
                            a Delaware corporation

                           By:
                              ------------------------------------
                           Name:
                                ----------------------------------
                           Its:
                               -----------------------------------

                                       4
<PAGE>
                                   EXHIBIT A

                       FOURTH AMENDMENT SPACE FLOOR PLAN

                    [INCLUDES FLOOR PLANS OF THE PREMISES]

                                       5
<PAGE>
                   FIFTH AMENDMENT TO OFFICE LEASE AGREEMENT

         THIS FIFTH AMENDMENT TO OFFICE LEASE AGREEMENT (this "Fifth
Amendment") is made and entered into as of the 30th day of September, 1996 (the
"Effective Date"), by and between HYATT PLAZA LIMITED PARTNERSHIP, a Virginia
limited partnership ("Landlord"), and AMERICAN MANAGEMENT SYSTEMS, INC., a
Delaware corporation ("Tenant"), with reference to the following:

                                   RECITALS:

         A.      Pursuant to an Office Lease Agreement dated August 12, 1993,
by and between Landlord and Tenant, as amended by that certain (i) First
Amendment to Office Lease Agreement dated August 31, 1994, (ii) Second
Amendment to Office Lease Agreement dated November 1, 1994, (iii) Third
Amendment to Office Lease Agreement dated October 2, 1995 and (iv) Fourth
Amendment to Office Lease Agreement dated August 12, 1996 (collectively, the
"Lease"), Landlord has leased to Tenant certain premises located at 12701 Fair
Lakes Circle, Fairfax, Virginia, 22033, as more particularly described therein.
All capitalized terms used herein, unless specifically defined, shall have the
same meaning and definition as used in the Lease.

         B.      Landlord and Tenant have agreed to amend the certain terms and
provisions of the Lease as hereinafter set forth.

         NOW, THEREFORE, for good and valuable consideration, the receipt and
sufficiency of which is hereby acknowledged, Landlord and Tenant agree as
follows:

<PAGE>

         1.      As an exercise of Tenant's Right of First Refusal Option,
Landlord and Tenant have agreed to expand the Premises to include an additional
3,350 square feet of Rentable Area located on the first (1st) floor of the
Building (the "Fifth Amendment Space"), commonly known as Suite 160, as more
particularly shown on Exhibit "A" attached hereto and made a part hereof by
this reference.  Base Rent for the Fifth Amendment Space ("Fifth Amendment
Space Base Rent") shall be as set forth below:

                 (i)      From October 1, 1996 to September 30, 1997, $21.00
         per square foot of Rentable Area, or the sum of $70,350.00 per year
         ($5,862.50 per month), and

                 (ii)     From October 1, 1997 to September 30, 1998, $21.63
         per square foot of Rentable Area, or the sum of $72,460.50 per year
         ($6,038.38 per month).

         2.      Tenant shall lease the Fifth Amendment Space in its "as is"
and "where is" condition, and Landlord shall have no obligation to make any
improvements as a condition of Tenant's acceptance thereof.  Tenant's lease of
Fifth Amendment Space shall commence October 1, 1996 (the "Fifth Amendment
Space Commencement Date") and shall terminate September 30, 1998 (the "Fifth
Amendment Space Expiration Date") (the "Fifth Amendment Space Initial Term").
On or before the Fifth Amendment Space Expiration Date, Tenant shall surrender
possession of the Premises to Landlord in accordance with the terms of the
Lease.

         3.      Commencing on January 1, 1998 and thereafter throughout the
Fifth Amendment Space Initial Term, Tenant shall pay on a monthly basis,
without demand, as Additional Rent for the Fifth Amendment Space, 1.33% of the
amount by which Operating Expenses exceed the Adjusted Base Operating Expenses.
Adjusted Base Operating Expenses shall, for purposes of

                                       2
<PAGE>
this Amendment, refer to the Operating Expenses incurred during the 1997
calendar year.  Such payments shall be made in accordance with Sections 6.01
and 6.02 of the Lease.

         4.      Tenant shall have the right to renew and extend the Fifth
Amendment Space Initial Term (the "Fifth Amendment Space Renewal Term") with
respect to the Fifth Amendment Space for one (1) Renewal Term (herein so
called) upon and subject to the following terms and conditions:

                 (a)      Tenant may extend the Fifth Amendment Space Initial
Term for one (1) Renewal Term of three (3) years, such Renewal Term commenting
on October 1, 1998 and expiring on September 30, 2001, by Tenant's giving
written notice thereof to Landlord on or before April 1, 1998.  If Tenant does
not exercise its rights to a Renewal Term in a timely manner, Tenant's failure
shall conclusively be deemed a waiver of its rights to a Renewal Term.

                 (b)      The exercise by Tenant of its rights to a Renewal
Term must be made, if at all, by written notice executed by Tenant and
delivered to Landlord on or before the date set forth above.  Once Tenant shall
exercise its rights to a Renewal Term, Tenant may not thereafter revoke such
exercise.  Tenant shall not have the right to exercise a Renewal Term if Tenant
is in Default under the Lease, as amended, either at the time Tenant gives
notice of its election or immediately prior to the  commencement of the Renewal
Term.

                 (c)      Tenant shall take the Fifth Amendment Space "as is"
for the Renewal Term and Landlord shall have no obligation to make any
improvements or alterations to the Fifth Amendment Space.

                                       3
<PAGE>
                 (d)      Base Rent per square foot of Rentable Area of the
Fifth Amendment Space for the first year of the Renewal Term shall be at the
rate of $22.28 per square feet for the Fifth Amendment Space.  Such Base Rate
shall be adjusted on October 1 of each subsequent year of the Renewal Term by
multiplying the Base Rent in effect on September 30 by 3.0% and adding the
product to the Base Rent then in effect.  The Adjusted Base Rent shall be in
effect until the next adjustment date.

                 (e)      Subject to subparagraph (d) above, the leasing of the
Fifth Amendment Space for the Renewal Term shall be upon the same terms and
conditions as are applicable for the Fifth Amendment Space Initial Term, and
shall be upon and subject to all of the provisions of the Lease, including,
without limitation, the obligation of Tenant to pay Tenant's Fifth Amendment
Space Additional Rent under the Lease.

         5.      From and after the Fifth Amendment Space Commencement Date
until the Fifth Amendment Space Expiration Date, the following terms used in
the Lease shall have the following ascribed meanings:

                 (a)      Premises: Refers to the Rentable Area demised to
Tenant by the Lease (set forth therein) and to the space demised to Tenant by
the First Amendment, Second Amendment, Third Amendment, Fourth Amendment and
Fifth Amendment Space, demised to Tenant by this Fifth Amendment.

                 (b)      Fifth Amendment Space: 3,350 square feet of Rentable
Area located on the first (1st) floor of the Building.

                                       4
<PAGE>
                 (c)      Fifth Amendment Space Renewal Term: Refers to the
Fifth Amendment Space Renewal Term, if exercised by Tenant pursuant to the
terms and conditions of this Fifth Amendment.

                 (d)      Rentable Area of the Premises:

<TABLE>
                                  <S>                                          <C>
                                  Original Lease Space                          84,236 square feet
                                  First Amendment Space                          7,926 square feet
                                  Second Amendment Space                         5,175 square feet
                                  Third Amendment Space                          5,327 square feet
                                  Fourth Amendment Space                           851 square feet
                                  Fifth Amendment Space                          3,350 square feet
                                                                               -------
                                  Total ----------------------------------     106,865 square feet
</TABLE>

                 (e)      Tenant's Proportionate Share:

<TABLE>
                                  <S>                                                       <C>
                                  Original Premises                                         33.37%
                                  First Amendment Space                                      3.14%
                                  Second Amendment Space                                     2.05%
                                  Third Amendment Space                                      2.11%
                                  Fourth Amendment Space                                      .34%
                                  Fifth Amendment Space                                      1.33%
                                                                                            ------
                                  Total........................................             42.34%
</TABLE>

                 (f)      Base Year:

<TABLE>
                                  <S>                                                         <C>
                                  Original Premises                                           1994
                                  First Amendment Space                                       1995
                                  Second Amendment Space                                      1995
                                  Third Amendment Space                                       1996
                                  Fourth Amendment Space                                      1996
                                  Fifth Amendment Space                                       1997
</TABLE>

         6.      Except as expressly modified by this Fifth Amendment, the
Lease remains unchanged and in full force and effect.

                     [Signatures appear on following page]

                                       5
<PAGE>
         IN WITNESS WHEREOF, Landlord and Tenant have executed this Fifth
Amendment as of the day and year first above written.

                              LANDLORD:
                              --------

                              HYATT PLAZA LIMITED PARTNERSHIP,
                              a Virginia limited partnership

                              By:     Fair Lakes Hyatt Limited Partnership, a
                                      Virginia general partnership, its general
                                      partner

                              By:     Fair Lakes of Virginia, Inc.,
                                      a Virginia corporation
                                      its general partner

                              By:                [SIG]
                                      -----------------------------------
                              Name:
                                      -----------------------------------
                              Its:
                                      -----------------------------------

                              TENANT:
                              ------

                              AMERICAN MANAGEMENT SYSTEMS,
                              INC., a Delaware corporation

                              By:     /s/ Frank A. Nicolai
                                      -----------------------------------
                              Name:
                                      -----------------------------------
                              Its:
                                      -----------------------------------

[FOLLOWED BY FLOOR PLANS ATTACHED AS EXHIBIT A]

                                       6
<PAGE>
                   FIFTH AMENDMENT TO OFFICE LEASE AGREEMENT

         THIS FIFTH AMENDMENT TO OFFICE LEASE AGREEMENT (the "Fifth Amendment")
is made and entered into this 30th day of November, 1996, but effective for all
purposes on the Assignment Date (hereinafter defined) by and among HYATT PLAZA
LIMITED PARTNERSHIP, a Virginia limited partnership, and AMERICAN MANAGEMENT
SYSTEMS, INC., a Delaware corporation (hereinafter sometimes referred to as
"Assignee" and/or "Tenant") with reference to the following:

                                   RECITALS:

         A.      Pursuant to the terms of that certain Office Lease Agreement
dated May 21, 1990, as amended by First Amendment dated July 12, 1990, Second
Amendment dated July 27, 1990, Third Amendment dated April 18, 1991 and Fourth
Amendment dated September 22, 1994 (collectively hereinafter referred to as the
"Lease"), Landlord leased to Trident Data Systems, Inc., a California
corporation ("Original Tenant") that certain premises (the "Premises") more
particularly described therein.  All capitalized terms used in this Fifth
Amendment which are not defined herein, shall have the same meaning and
definition as used in the Lease.

         B.      Pursuant to that certain Assignment of Office Lease Agreement
dated __________, 1996 (the "Assignment") by and between Original Tenant and
Assignee, Original Tenant, with Landlord's consent, has assigned to Assignee
all of its right, title and interest in and to the Lease (as defined in the
Assignment).  The Assignment contains certain provisions which permit the
Original Tenant and the Assignee to terminate the Assignment should certain
events occur.  The date that all of the rights of Assignee and the Original
Tenant to terminate the Assignment cease and the assignment of the Lease to the
Assignee becomes effective is hereinafter referred to as the "Assignment Date."

         C.      The parties have agreed to amend certain terms and provisions
of the Lease, as of the Assignment Date.

         NOW, THEREFORE, for good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, the parties agree as follows:

         1.      From and after the Assignment Date, any and all references in
the  Lease to the term Tenant shall mean and refer to the Assignee.

         2.      As of the Assignment Date, Tenant exercises its right of
renewal set forth in Rider No. 4 of the Lease.  As a result of the foregoing
exercise, the Term of the Lease has been extended for an additional six (6)
years, two (2) months (the "Extension Term"), commencing on January 1, 1998
(the "Extension Commencement Date") and expiring on February 29, 2004 (the
"Expiration Date").  The Base Rent for the Extension Term shall be $413,462.60
per year ($34,455.22 per month), based upon $20.60 times 20,071, the number of
square feet of Rentable Area in the Premises.  The Base Rent for the Extension
Term shall be increased by 3% annually on each

<PAGE>
January 1st throughout the Extension Term, with the first increase occurring on
January 1, 1999.  During the Extension Term, the Base Operating Expenses Amount
and the Base Real Estate Taxes Amount shall be equal to Tenant's proportionate
share of the actual Operating Expenses and Base Real Estate Taxes incurred by
Landlord with respect to the Building during calendar year 1998.

         3.      Landlord and Tenant agree that Tenant shall lease the Premises
in its "as is" and "where is" condition during the Extension Term and Landlord
shall not be obligated to make any improvements whatsoever to the Premises as a
condition of Tenant's extension of the Lease, nor shall Landlord be obligated
to provide Tenant any allowances.

         4.      As of the Assignment Date, Article 12 - Alterations shall be
deleted in its entirety, and replaced with the following:

                 "After the initial Leasehold Improvements are completed,
         Tenant shall not, at any time during the Term, without Landlord's
         prior written consent, make any Alterations (hereinafter defined) to
         the Premises.  Should Tenant desire any Alterations, Tenant agrees to
         submit all plans and specifications for same to Landlord for
         Landlord's written approval, before beginning such work and Landlord's
         approval shall not be unreasonably withheld, conditioned or delayed.
         Provided Tenant has supplied Landlord with information and plans for
         the Alterations which reasonably details the nature and scope of the
         same, Landlord's failure to respond to Tenant's request for approval
         within ten (10) business days after receipt of the information, plans
         and request for approval, shall be deemed to be Landlord's approval of
         the same.  Landlord shall not be considered as unreasonably
         withholding its approval by refusing to consent to any Alterations
         which alter the exterior appearance of the Building, or the public
         lobbies, corridors, or common areas thereof, which will or are likely
         to cause any weakening of any part of the structure of the Premises or
         Building or which may cause damage or disruption to any Building
         system and such damage or disruption is not repaired as part of the
         Alterations.  Upon Tenant's receipt of Landlord's written approval,
         Tenant may proceed with the construction of the approved Alterations,
         but only so long as they are in substantial compliance with the plans
         and specifications approved by Landlord and provisions of this Article
         12.  Additionally, the construction of any alterations (regardless of
         whether or not Landlord's prior approval of the work is required by
         this Lease), the alterations themselves, or any maintenance thereof
         shall comply with all building, safety, fire, plumbing, electrical and
         other codes and governmental and insurance requirements, and shall not
         require an amount of water, electricity, gas, heat, ventilation, or
         air-conditioning which exceeds reasonable level of consumption for a
         modem business office unless prior written arrangements reasonably
         satisfactory to Landlord are made with respect thereto.  All
         alterations shall be made at Tenant's expense, either by Tenant's
         contractors which have been approved in advance by Landlord or at
         Tenant's option, by Landlord's contractors on terms reasonably
         satisfactory to Tenant.  In the event Landlord actually constructs the
         alterations or is retained by Tenant to supervise or manage  the
         construction by contractors selected by Tenant and approved by
         Landlord, then Tenant shall pay to Landlord a fee equal to ten percent
         (10%) of the actual costs of such work, such fee to cover Landlord's
         overhead related to the work, including, but not limited to,
         Landlord's review of the plans and specifications, coordination of the

                                       2
<PAGE>
         work, consultation with professionals regarding the work, and general
         administration allocable to the work.  The foregoing fee will not be
         charged in circumstances where Landlord has merely approved the
         Alterations.  All such construction shall be completed promptly and in
         a good and workmanlike manner and shall be performed in compliance
         with the lien provisions set forth in Article 13 of the Lease.

                 As used in the Lease, the term Alterations refers to work
         performed after the completion of the initial Leasehold Improvements
         which would reasonably be considered major construction, renovations
         or changes to the Premises, having a material impact on the appearance
         of the Premises or to other portions of the Building, or would
         otherwise have a material impact (structural, mechanical, operational
         or otherwise) upon the Building, and/or the total cost of the
         construction, renovations or changes is more than $75,000.00.
         Alterations do not include, by way of example, by hanging of pictures,
         the movement of furniture and flexible space walls or partitions, or
         the painting of the interior of the Premises.  Prior to commencing any
         alterations, Tenant will coordinate with Landlord so as to schedule
         the movement of men, material and equipment through the Building's
         common  areas in a manner which does not unreasonably interrupt the
         normal Building operations and the use and enjoyment of the Building
         by other tenants therein.

                 All existing Improvements and improvements to the Premises
         constructed by Tenant and paid for by Tenant from funds supplied by
         Landlord either in the form of allowances or credits shall be and
         remain the Landlord's property, and shall not be removed from the
         Premises.  Tenant shall have the right, upon expiration of the Term,
         to remove, at Tenant's expense, all alterations to the Premises (other
         than the Existing Improvements and the improvements or alterations
         paid by allowances granted by Landlord); specialized trade fixtures or
         other systems or items installed by Tenant pursuant to Article 12 of
         the Lease, and; moveable trade fixtures.  Tenant agrees to remove, at
         Tenant's expense, all of its furnishings, furniture and movable
         personal property by the Expiration Date.  Tenant will promptly
         restore any damage to the Premises or Building caused by its removal
         of its property."

                                       3
<PAGE>

         5.      From and after the Extension Commencement Date, the following
terms as defined in the Lease shall have the following meanings:

                 (a)      Term: Thirteen (13) years, five (5) months and
seventeen (17) days.

                 (b)      Expiration Date:  February 29, 2004.

                 (c)      Base Rent:$413,462.60 per year ($34,455.22 per
month), which amount is based upon $20.60 per square foot of Rentable Area in
the Premises, effective as of the Extension Commencement Date, as adjusted
pursuant to Section 5.02 of  the Lease, as modified herein.

                 (d)      Adjustment Factor:  3.0%

                 (e)      Tenant's Proportionate Share:8.05%

         6.      From and after the Assignment Date, Section 5.02 of the Lease
shall be deleted and the following inserted in lieu thereof.

                          "(a)    During the Term of this Lease, the Base Rent
         shall be adjusted on January 1, 1999 and the first day of January
         thereafter pursuant to this Section.  The dates described in this
         Section for computing the adjustment in Base Rent are hereinafter
         sometimes referred to collectively as "Rental Adjustment Dates" and
         singularly as a "Rental Adjustment Date".  All adjustment to Base Rent
         required by this Section 5.02 shall be made as hereinafter described:

                 (1)      On the first Rental Adjustment Date, the Base Rent
         shall be multiplied by the Adjustment Factor and the amount computed
         shall be added to the Base Rent as of the first Rental Adjustment Date
         and the resulting sum shall be the adjusted Base Rent (hereinafter the
         "Adjusted Rent") to be paid by the Tenant to Landlord, in advance,
         without demand, in equal monthly installments, on the first day of
         each calendar month until the next Rental Adjustment Date.

                 (2)      On the second Rental Adjustment Date and on every
         Rental Adjustment Date throughout the term of this Lease, the Adjusted
         Rent payable in the year immediately preceding the Rental Adjustment
         Date in question shall be multiplied by the Adjustment Factor and the
         amount computed shall be added to the Adjusted Rent for the year
         immediately preceding the Rental Adjustment Date and the resulting sum
         shall be the Adjusted Rent for that rental year to be paid by the
         Tenant to Landlord, in advance, without demand, in equal monthly
         installments, on the first day of each calendar month until the next
         Rental Adjustment Date.

                          (b)     Landlord shall provide Tenant with written
         notice of each adjustment pursuant to Section 3.02(b), which notice
         shall provide the basis upon which such adjustment has been
         calculated; provided, however, that if for any reason Landlord

                                       4
<PAGE>
         does not notify Tenant of the amount of such adjustment until after
         any Rental Adjustment Date, Tenant shall continue to pay the Base Rent
         or Adjusted Rent, as the case may be, payable prior to the Rental
         Adjustment Date, and Tenant, within five (5) days following Landlord's
         delivery of written notice of such adjustment shall pay to Landlord
         in a lump sum the amount of any increase in the Base Rent resulting
         from such adjustment for all months in the existing calendar year
         prior to and including the month 'in which such notice of adjustment
         is received and during the remainder of such year Tenant shall pay to
         Landlord the Adjusted Rent as set forth in such notice."

         7.      Section 1.01.6 and all references to Base Net Rent shall be
deleted.

         8.      This Fifth Amendment shall be effective only upon the
Assignment Date.  Should, for any reason, either the Original Tenant or the
Assignee terminate the Assignment, then this Fifth Amendment shall be null and
void and the Original Tenant shall continue to occupy the Premises pursuant to
the terms of the Lease, unmodified, and in full force and effect.

                                       5
<PAGE>
                 IN WITNESS WHEREOF, Landlord and Tenant have executed this
Fifth Amendment as of the day and year first above written.

                               LANDLORD:
                               ---------

                               HYATT PLAZA LIMITED PARTNERSHIP,
                               a Virginia limited partnership

                               By:  Fair Lakes Hyatt Limited Partnership, a
                                    Virginia general partnership, its
                                    general partner

                               By:  Fair Lakes of Virginia, Inc.,
                                    a Virginia corporation
                                    its general partner

                               By:   /s/ Milton V. Peterson
                                  --------------------------------
                               Name: Milton V. Peterson
                                     -----------------------------
                               Its:  President
                                     -----------------------------

                               ASSIGNEE/TENANT:
                               ----------------

                               AMERICAN MANAGEMENT SYSTEMS, INC.,
                                 a Delaware corporation, successor-in-interest
                                 to Trident Data Systems, Inc., a California
                                 corporation

                               By: /s/ Frank Nicolai
                                   --------------------------------
                               Name:
                                     ------------------------------
                               Its:
                                   --------------------------------

                                       6
<PAGE>
                              ASSIGNMENT OF LEASE

         THIS ASSIGNMENT OF LEASE (the "Assignment") is made and entered into
this 30th day of September, 1996 by and between Trident Data Systems, Inc. (the
"Assignor") and American Management Systems, Inc. (the "Assignee"), with
reference to the following:

                                   RECITALS:

         A.      Pursuant to a Lease Agreement, dated May 17, 1990 as amended
by the First Amendment dated July 12, 1990, the Second Amendment dated July 27,
1990, the Third Amendment dated April 18, 1991 and the Fourth Amendment dated
September 22, 1994 (collectively the "Lease") by and between Assignor and Hyatt
Plaza Limited Partnership (the "Landlord"), Assignor leased certain premises
totaling 20,071 rentable square feet more particularly described therein.

         B.      Assignor desires to assign unto the Assignee all of the
Assignor's rights, title and interest under the Lease.

         NOW, THEREFORE, for good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, the parties hereby agree as
follows:

         1.      Effective as of February 1, 1997 (the "Effective Date")
Assignor assigns all of its rights and obligations under the Lease and Assignee
accepts such assignment of

                                  Page 1 of 4
<PAGE>
all the Assignor's rights and obligations thereunder.  In the event the
Premises are not made available to the Assignee by the Effective Date, the
Assignor shall pay the Assignee a penalty of $1,219.87 for each day the
Premises are not available beyond the Effective Date.  In addition, if the
Premises are not made available to the Assignee by March 1, 1997, the Assignee
shall have the option to cancel the Assignment.

         2.      From and after the Effective Date, Assignee will perform all
of the provisions to be performed under the Lease by Assignor and Landlord
shall be entitled to all the rights, benefits and rentals accruing thereunder.

         3.      The Assignor shall pay the Assignee $80,000 in two equal
installments of $40,000 payable on January 1, 1997 and March 1, 1997.  In
addition, the Assignor shall pay a brokerage commission to Cushman & Wakefield
equal to $12,142.96 as the Assignee's broker representative.  The amounts due
from Assignor to Assignee under this paragraph 3 are solely the obligation of
the Assignor and shall under no circumstances have any effect upon the Lease or
this Assignment.

         4.      The Assignor represents and warrants that the monthly base
rent for the Premises will be $36,596.12 per month through December 31, 1997.
In addition, the Assignor currently pays $1,610.24 per month in estimated real
estate tax and operating expense passthroughs which is subject to adjustment
based upon actual costs pursuant to Article 6 of the Lease.

                                  Page 2 of 4
<PAGE>
         5.      This Assignment is contingent on Pacific Mutual Life Insurance
Company countersigning a lease with Trident Data Systems, Inc. for office space
at 10455 White Granite Drive, Oakton, Virginia.  In the event the Assignor has
not satisfied the contingency within ten (10) days of the date hereof, then the
Assignor shall have the option to rescind this Assignment at any time within
twenty (20) days thereafter.

         6.      Assignor, Assignee and Landlord acknowledge and agree that the
Assignee shall have no rights to the security deposit under the Lease and that
the security deposit will be returned to the Assignor by Landlord in accordance
with the terms of a separate agreement.

         WITNESS the following signatures and seals of Assignor and Assignee
made as of the date first above written.

                                  ASSIGNOR:
                                  --------

                                  TRIDENT DATA SYSTEMS, INC.

                                  By:    /s/ David A. Muckley
                                     ---------------------------------
                                  Name:  David A. Muckley
                                      --------------------------------
                                  Its:  President & CEO
                                        ------------------------------

                                  ASSIGNEE:
                                  --------

                                  AMERICAN MANAGEMENT SYSTEMS, INC.

                                  By:   /s/ Frank A. Nicolai
                                     ---------------------------------
                                  Name:
                                      --------------------------------
                                  Its:
                                     ---------------------------------

                                  Page 3 of 4
<PAGE>

         The undersigned, the Landlord of the above referenced Lease, hereby
executes this Assignment solely to evidence its consent to the assignment by
the Assignor to the Assignee.  The undersigned reserves its rights under the
Lease to consent and approve any future assignment of the Lease.  The consent
by Landlord shall not be deemed a release of the Assignor of the Tenant's
obligations under the Lease accruing prior to the Effective Date of this
Assignment.  Upon the Assignor surrendering possession by the Effective Date,
the Assignor and Landlord shall have no further obligations to each other under
the Lease except for the following provisions which expressly state that such
provisions shall survive termination of the Lease: Articles 5.04, 6.01 and
6.02.

                           LANDLORD:
                           --------

                           By:  Fair Lakes Hyatt Limited Partnership*, its g.p.
                           By:  Fair Lakes of Virginia, Inc.**, its gen. partner

                           By:    /s/ Milton V. Peterson
                              ---------------------------------
                           Name: Milton V. Peterson
                           Its: President

                           *   a Virginia limited partnership
                           **  a Virginia corporation

                           By:
                              -----------------------------
                           Name:
                                ----------------------------
                           Its:
                               -----------------------------

                           By:
                              ------------------------------
                           Name:
                                -----------------------------
                           Its:
                               ------------------------------

                                  Page 4 of 4

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