Document:

EXHIBIT 10.20

                                    SUBLEASE

                                     between

                            PG&E GENERATING COMPANY

                                       and

                                 INFORMAX, INC.

<PAGE>

                                Table of Contents
                                -----------------

<TABLE>
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<S>      <C>      <C>                                                                                        <C>
  1.     Subleased Premises and Term .........................................................................1
         (a)      Term .......................................................................................1
         (b)      Inability to Deliver Possession ............................................................1
         (c)      Measurement of Subleased Premises ..........................................................2
  2.     Construction of Subleased Premises ..................................................................2
         (a)      Delivery and Acceptance ....................................................................2
         (b)      Initial Leasehold Improvements .............................................................2
         (c)      Architectural Services .....................................................................2
         (d)      Design and Construction Schedule ...........................................................3
         (e)      Construction ...............................................................................3
         (f)      Permits ....................................................................................3
         (g)      Leasehold Improvement Allowance ............................................................3
  3.     Rent.................................................................................................4
         (a)      Base Rental ................................................................................4
         (b)      Additional Base Rental .....................................................................4
         (c)      Payment of Rent ............................................................................5
         (d)      Late Payment ...............................................................................5
  4.     Permitted Use .......................................................................................5
  5.     Incorporation of Lease ..............................................................................5
  6.     Transmittal of Notices and Demands ..................................................................6
  7.     Landlord's Consent to Certain Acts ..................................................................7
  8.     Sublandlord's Right to Cure Subtenant's Default .....................................................7
  9.     Utilities ...........................................................................................7
         (a)      Overtime Heating and Air Conditioning ......................................................7
         (b)      Excessive Electrical Use ...................................................................7
 10.     Assignment of Sublease ..............................................................................7
 11.     Alterations to Subleased Premises ...................................................................8
 12.     Signage .............................................................................................9
         (a)      Directory and Suite Entrance Signs .........................................................9
         (b)      Consent Required ...........................................................................9
 13.     Indemnity ...........................................................................................9
 14.     Subtenant's Insurance ..............................................................................10
 15.     Eminent Domain, Loss by Casualty ...................................................................10
 16.     Default ............................................................................................10
         (a)      Events of Default .........................................................................10
         (b)      Remedies ..................................................................................11
 17.     Notice and Demands .................................................................................11
 18.     Surrender of Subleased Premises ....................................................................11
 19.     Parking ............................................................................................12
 20.     Brokerage Fees .....................................................................................12
 21.     Authority to Execute Lease .........................................................................12
 22.     Security Deposit ...................................................................................12
 23.     Subtenant's Roof Use ...............................................................................14
 24.     Right of First Opportunity .........................................................................15
         (a)      Option and Exercise .......................................................................15
         (b)      Base Rental ...............................................................................16
 25.     Consent of Landlord ................................................................................17
 26.     Subordination of Sublandlord's Lien ................................................................18

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                                Table of Contents
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<S>      <C>      <C>                                                                                        <C>
 27.     Non-Disturbance Agreement ..........................................................................18
 28.     Quiet Enjoyment ....................................................................................18
 29.     Miscellaneous ......................................................................................18
         (a)      No Offer ..................................................................................18
         (b)      No Partnership ............................................................................18
         (c)      Time of the Essence .......................................................................18
         (d)      Separability ..............................................................................18
         (e)      Counterparts ..............................................................................18
         (f)      Merger ....................................................................................18
</TABLE>

Exhibits

         Exhibit A - Lease
         Exhibit B - Floor Plan of Subleased Premises
         Exhibit C - Commencement Letter
         Exhibit D - Base Building Improvements
         Exhibit E - Subtenant's Space Plan
         Exhibit F - Construction Schedule
         Exhibit G - Sublandlord Supplied Materials

<PAGE>

                                    SUBLEASE

         This Sublease  ("Sublease")  made as of the 21 day of September,  2000,
between   PG&E   GENERATING    COMPANY,   a   California   general   partnership
("Sublandlord"),  and  INFORMAX,  INC., a Delaware  corporation  qualified to do
business in the State of Maryland ("Subtenant").

                                   WITNESSETH

         WHEREAS,  Sublandlord,  as  successor  in interest  to U.S.  Generating
Company,  a California  general  partnership,  is the  "Tenant"  under a certain
Office Lease  Agreement  dated June 25, 1998 (the  "Lease"),  a true and correct
copy of which is attached hereto as Exhibit A and hereby made a part hereof,  by
which  it has  leased  the  first  (1st)  through  the  eleventh  (11th)  floors
("Premises")  of the  building  located  at  7600  Wisconsin  Avenue,  Bethesda,
Maryland  20814,  commonly  known  as  Bethesda  Place  II (the  "Building")from
Bethesda  Place  II  Limited   Partnership,   a  Maryland  limited   partnership
("Landlord"); and

         WHEREAS,   Subtenant   desires  to  sublease  from   Sublandlord,   and
Sublandlord desires to sublease to Subtenant,  the approximately 36,190 rentable
square  feet of space on the tenth  (10th)  and  eleventh  (11th)  floors of the
Building (the "Subleased Premises") shown as the cross-hatched area on the floor
plans  attached  hereto as Exhibit B and hereby made a part hereof in accordance
with the terms and conditions hereinafter provided;

         NOW, THEREFORE, in consideration of the rents, covenants and agreements
herein contained, IT IS HEREBY AGREED AS FOLLOWS:

         1.       SUBLEASED PREMISES AND TERM.

                  (A) TERM.  Sublandlord hereby subleases the Subleased Premises
to  Subtenant  and  Subtenant  hereby  subleases  the  Subleased  Premises  from
Sublandlord  upon and subject to the terms,  covenants,  rentals and  conditions
herein set forth,  for a term (the "Term")  consisting a Preliminary  Term and a
Main Term. The Preliminary Term shall commence on the date Sublandlord  delivers
possession of the Subleased Premises to Subtenant (the "Preliminary Commencement
Date") and shall  expire  ninety  (90) days after the  Preliminary  Commencement
Date. The Main Term shall commence on the ninety-first (91st)  day following the
Preliminary  Commencement  Date (the "Rent  Commencement  Date") and expiring on
October 31, 2012 (the "Termination Date");  provided,  however that if the Lease
shall be  terminated  for any reason prior to the  Termination  Date,  then this
Sublease shall expire on the termination date of the Lease.

         For purposes of this Sublease, the term "Sublease Year" shall mean each
twelve (12) month period during the Term beginning on the first day of the month
coincident with or next following the Rent Commencement Date and each subsequent
anniversary thereof; provided, that the last Sublease Year of the Term shall end
on the Termination Date and if the Rent  Commencement  Date is not the first day
of a calendar month, the period between the Rent Commencement Date and the first
day of the next calendar month shall be included in the first Sublease Year.

                  (B) INABILITY TO DELIVER POSSESSION.  Sublandlord  anticipates
delivering  possession  of the  Subleased  Premises to Subtenant on September 1,
2000 (the "Anticipated  Preliminary  Commencement Date") If Sublandlord shall be
unable to deliver  possession  of the  Subleased  Premises to  Subtenant  on the
Anticipated Preliminary Commencement Date for any reason,  Sublandlord shall not
be subject to any liability  for the failure to tender  possession on said date.
In such event,  the rent covenanted to be paid herein shall not commence and the
Rent Commencement  Date shall not occur until the ninety-first  (91st) day after
possession of the Subleased  Premises is tendered to Subtenant.  No such failure
to give possession on the

<PAGE>

Anticipated Preliminary  Commencement Date shall in any other respect affect the
validity of this Sublease or the obligations of Subtenant  hereunder,  nor shall
the same be  construed to extend the Term,  which shall in all events  expire on
the Termination Date. Within fifteen (15) days after the Rent Commencement Date,
Sublandlord  and Subtenant  shall execute a  Commencement  Letter in the form of
Exhibit  C.  Notwithstanding  any other  provision  hereof to the  contrary,  if
Sublandlord has not delivered  possession of the Subleased Premises to Subtenant
by  December  1,  2000,  for any  reason,  Subtenant,  at its sole  option,  may
terminate this Sublease by written  notice to Sublandlord on or before  December
31, 2000, unless  Sublandlord  shall have delivered  possession of the Subleased
Premises to Subtenant before such notice. In the event Subtenant terminates this
Sublease pursuant to this paragraph, Sublandlord shall refund any advance Rental
payment and return any  security  deposit to  Subtenant,  and the parties  shall
thereupon be relieved of any and all liability hereunder.

                  (c) MEASUREMENT OF SUBLEASED PREMISES.  Before the Preliminary
Commencement  Date,  Landlord's  architect  shall  determine the exact number of
rentable  square  feet  in  the  Subleased   Premises  in  accordance  with  the
Washington,  D.C. Association of Realtors method (hereinafter  defined), and the
Base  Rental  and  Subtenant's  Share  (each   hereinafter   defined)  shall  be
proportionately adjusted.  Subtenant's architect shall have the right to confirm
Landlord's architect's measurements. The parties agree that the Rentable Area of
the Subleased Premises,  determined  pursuant to this section,  and the adjusted
Base Rental and Subtenant's Share shall be set forth in the Commencement Letter,
attached  hereto as Exhibit C, to be executed by the parties within fifteen (15)
days after the Rent  Commencement  Date of the Lease Term.  As used herein,  the
"Washington,  D.C.  Association of Realtors  Method" shall mean the  Washington,
D.C. Association of Realtors Standard Method of Measurement dated January 1989.

         2.       CONSTRUCTION OF SUBLEASED PREMISES.

                  (A) DELIVERY AND ACCEPTANCE.  Sublandlord  shall deliver,  and
Subtenant agrees to accept,  possession of the Subleased  Premises with only the
"Base Building Improvements" listed on the attached Exhibit D completed.

                  (B) INITIAL  LEASEHOLD  IMPROVEMENTS.  During the  Preliminary
Term, Subtenant,  at Subtenant's sole cost and expense (subject to reimbursement
by  Sublandlord  pursuant to Paragraph  2(g)),  shall  construct  the  Subleased
Premises,  including the elevator lobby,  for Subtenant's use and occupancy (the
"Initial  Leasehold  Improvements")  in accordance  with a space plan reasonably
approved by  Sublandlord  and Landlord and the Leasehold  Improvement  Plans and
Specifications  (hereinafter  defined), and in accordance with the provisions of
this Paragraph 2.

                  (C) ARCHITECTURAL SERVICES. An architect selected by Subtenant
and  approved  by  Sublandlord  and  Landlord,   which  approval  shall  not  be
unreasonably withheld,  conditioned or delayed (herein "Subtenant's  Architect")
shall,  at  Subtenant's  expense,  perform  all  of the  architectural  services
required  in  connection  with  the   construction  of  the  Initial   Leasehold
Improvements,  including,  but not  limited  to,  preparation  of  space  plans,
standard  furniture and equipment  layout plans,  dimensional  partition  plans,
dimensional electrical, telephone and computer outlets, reflected ceiling plans,
door  and  hardware  selections,  and  room  finish  schedules,  including  wall
coverings,  carpet  and tile  floor  covers  and  other  necessary  construction
details.  The plans and  specifications  for the Initial Leasehold  Improvements
shall be approved in writing by Landlord and  Sublandlord,  which approval shall
not be unreasonably  withheld,  conditioned or delayed. The approved final plans
and specifications for the Leasehold  Improvements are herein referred to as the
"Leasehold  Improvement  Plans and  Specifications".  The  approved  space  plan
("Subtenant's  Space Plan")  shall be attached  hereto and made a part hereof as
Exhibit E.

                                                     PG&E Generating Company and
                                                                  InforMax, Inc.
                                                     Sublease Agreement - Page 2

<PAGE>

                  (D)  DESIGN  AND  CONSTRUCTION  SCHEDULE.  In order to  insure
timely  completion  of  construction  of  the  Initial  Leasehold  Improvements,
Subtenant shall prepare and Sublandlord  shall approve a timetable  whereby each
party shall be obligated to meet  certain  dates in the design and  construction
process (the "Construction Schedule").  The approved Construction Schedule shall
be attached  hereto as Exhibit F.  Subtenant's  failure to meet any deadlines in
the Construction Schedule shall not constitute a default hereunder.

                  (E)  CONSTRUCTION.  The construction of the Initial  Leasehold
Improvements  shall be performed in accordance with the following  provisions of
this Paragraph 2(e):

                           (i)   Subtenant   shall   contract   with  a  general
contractor  approved by  Sublandlord  and Landlord,  which approval shall not be
unreasonably withheld ("Subtenant's  Contractor") for performance of the Initial
Leasehold Improvements.

                           (ii) All  contractors  performing  such  construction
must be  licensed  to  perform  such  work in the  State of  Maryland,  and such
contractors,  or Subtenant, must maintain all insurance required by Section 16.B
of the Lease.

                           (iii)  Such   construction   shall  be  performed  in
accordance  with the  Leasehold  Improvement  Plans and  Specifications,  and in
compliance with all legal  requirements  and all matters of record affecting the
Building.  All  materials  and  equipment  to be  incorporated  into the Initial
Leasehold  Improvements  shall be new and of good quality and in good  operating
condition,  and  construction  shall be free from any known  faults and defects.
Construction   not  conforming  to  these   requirements   shall  be  corrected.
Sublandlord and Landlord,  at their sole cost and expense,  shall be entitled to
oversee all construction by Subtenant hereunder in order to assure compliance by
Subtenant of the approved plans and specifications.

                           (iv)  Subtenant  shall   indemnify   Sublandlord  and
Landlord  against (A) any damage sustained in connection with the work performed
by any  contractors  retained  by  Subtenant,  unless  such  damage is caused by
negligence or willful  misconduct of Landlord,  Sublandlord or their  respective
agents, employees or contractors,  and (B) any mechanics' or materialmen's liens
against the  Premises or the  Building  arising  from the work  performed by any
contractors retained by Subtenant.

                  (F) PERMITS.  Subtenant shall be responsible for obtaining the
construction  and  occupancy  permits for the  Subleased  Premises and any other
permits  or  licenses  necessary  for  its  lawful  occupancy  of the  Subleased
Premises. This requirement shall not relieve Subtenant of its liability for Base
Rental (as defined in Paragraph  3(a)) and Additional Base Rental (as defined in
Paragraph  3(b)) from the Rent  Commencement  Date in the event all said permits
have not been acquired prior thereto.

                  (G) LEASEHOLD IMPROVEMENT ALLOWANCE. Sublandlord shall provide
Subtenant with  materials,  on site,  costing  approximately  Sixty Thousand Six
Hundred Ninety-seven and 46/100 Dollars ($60,697.46), for incorporation into the
Initial  Leasehold  Improvements.  Those  materials (the  "Sublandlord  Supplied
Materials")  and the cost of the same are  listed  on the  attached  Exhibit  G.
Sublandlord  shall also provide  Subtenant  with an  improvement  allowance (the
"Leasehold  Improvement  Allowance")  not  to  exceed  One  Million  Eighty-five
Thousand Seven Hundred and No/100 Dollars  ($1,085,700.00) [i.e., Thirty Dollars
($30.00)  per square foot of rentable  area in the  Subleased  Premises],  to be
applied  to the  cost  of the  Initial  Leasehold  Improvements.  The  Leasehold
Improvement Allowance shall be paid by Sublandlord to Subtenant in not more than
three (3) installments, payable jointly to Subtenant and Subtenant's Contractor,
as  the  Initial  Leasehold  Improvements  are  completed.  The  first  two  (2)
installments (which shall not exceed, in the aggregate,  two thirds (2/3) of the
total amount of the Leasehold Improvement

                                                     PG&E Generating Company and
                                                                  InforMax, Inc.
                                                     Sublease Agreement - Page 3

<PAGE>

Allowance)  shall be paid  (provided that Subtenant is not in default under this
Sublease)  within  thirty (30) days after  Subtenant's  submission  of a written
payment request identifying the items for which payment is sought and the amount
of such payment,  which payment  request is  accompanied by (i) a certificate of
Subtenant's  architect to Sublandlord and any other party reasonably  designated
by  Sublandlord,  specifying  that the  work  for  which  Subtenant  is  seeking
reimbursement  has been performed in accordance  with the Leasehold  Improvement
Plans and  Specifications,  (ii)  invoices  for the work for which  Subtenant is
seeking  reimbursement,  and (iii)  interim (or if final  payment for an item is
sought,  final) releases of lien, in form and substance reasonably  satisfactory
to  Sublandlord,  from all  contractors  and  materialmen  who supplied labor or
materials for the work for which Subtenant is seeking  reimbursement.  The final
installment of the Leasehold  Improvement Allowance shall be paid (provided that
Subtenant is not in default under this  Sublease)  within thirty (30) days after
the last to occur of the following:  (i) final  completion of all of the Initial
Leasehold  Improvements  in  accordance  with the terms of this  Sublease,  (ii)
evidence of the  satisfaction of the  requirements  of governmental  authorities
with respect thereto, (iii) receipt of releases of lien from all contractors and
materialmen   who  supplied  labor  or  materials  for  the  Initial   Leasehold
Improvements,  (iv)  Sublandlord's  receipt of from  Subtenant  of invoices  for
materials and labor for the Initial Leasehold Improvements in an amount equal to
or in excess of the Leasehold  Improvement  Allowance,  and (v) Subtenant having
commenced to use the Subleased Premises for office purposes.

         3. RENT.  Commencing on the Rent Commencement Date, Subtenant covenants
and agrees to pay to Sublandlord as rent for the Subleased Premises:

                  (A) BASE RENTAL.  A base rental of One Million  Three  Hundred
Fifty-seven Thousand One Hundred Twenty-five and No/100 Dollars  ($1,357,125.00)
per annum ("Base Rental") payable in equal monthly  installments of monthly base
rent in the amount of One  Hundred  Thirteen  Thousand  Ninety-three  and 75/100
Dollars  ($113,093.75)  ("Monthly Base Rental").  Subtenant  shall pay the first
monthly  installment of Base Rental upon  execution of this Sublease.  Subtenant
shall pay the remaining  monthly  installments of Base Rental in advance without
prior demand,  and without  deduction,  abatement,  recoupment or set-off of any
kind, upon the first day of each and every calendar month throughout the Term.

                           On the first day of the second  Sublease Year, and on
the first day of each Sublease Year thereafter  during the Term, the Base Rental
(then in effect) shall be increased by two and one-half percent (2.5%).

                  (B)  ADDITIONAL  BASE RENTAL.  Additional  Base  Rental,  upon
demand therefor by Sublessor, consisting of:

                           (i) Eighteen and twenty-four ,one hundredths  percent
(18.24%)  ("Subtenant's  Share", the ratio of the rentable area of the Subleased
Premises to the rentable  area of the  Building,  subject to  adjustment  if the
rentable area of the Subleased  Premises  changes in accordance  with  Paragraph
1(c) hereof) of any increases in "Expenses" (as defined in Sections  1.B(11) and
4.E of the Lease, excluding the charges for heating and air conditioning paid by
Subtenant  pursuant to Paragraph  3(b)(v)  below) during each calendar year over
the  Expenses  for  calendar  year 2001,  adjusted  (as to each  calendar  year,
including  calendar  year 2001),  if the  Building  is not at least  ninety-five
percent  (95%)  occupied  for the full  calendar  year,  to reflect  ninety-five
percent  (95%)  occupancy  for the full calendar year (the "Expense Base Year"),
which Expense  increases shall be billed by Sublandlord and payable by Subtenant
in the same manner as set forth in Section 4.D of the Lease;

                           (ii)  Subtenant's  Share of any  increases in "Taxes"
(as defined in Section  4.E(7) of the Lease) during each tax year over the Taxes
for the tax year ending June 30, 2002,

                                                     PG&E Generating Company and
                                                                  InforMax, Inc.
                                                     Sublease Agreement - Page 4

<PAGE>

or if later,  the first  twelve  (12)  months  in which  the  Building  is fully
assessed as a completed  building  (the "Tax Base  Year"),  which Tax  increases
shall be billed by  Sublandlord  and payable by  Subtenant in the same manner as
set forth in Section 4.D of the Lease;

                           (iii)  Subtenant's  Share  of  any  increases  in the
charges for  electricity  supplied  to the  Building  (exclusive  of charges for
electricity  consumption  which is separately  metered or submetered and payable
directly by subtenants  pursuant to their  subleases)  during each calendar year
over the charges for electricity  supplied to the Building (exclusive of charges
for  electricity  consumption  which is  separately  metered or  submetered  and
payable  directly by subtenants  pursuant to their  subleases) for calendar year
2001, which electric charge increases shall be billed by Sublandlord and payable
by Subtenant in the same manner as set forth in Section 4.D of the Lease;

                           (iv)  Subtenant's  Share of all taxes (if any) passed
through by Landlord to the  tenants of the  Building  pursuant to Section 4.G of
the Lease;

                           (v) The actual cost to Sublandlord of heating and air
conditioning  supplied to the Subleased Premises after normal Building operating
hours at Subtenant's request, pursuant to Paragraph 9(a) of this Sublease, which
amounts shall be payable by Subtenant to Sublandlord  within ten (10) days after
delivery to Subtenant of a bill therefor; and

                           (vi) Any  other  payment  (other  than  Base  Rental)
required  to be paid  by  Subtenant  to  Sublandlord  under  the  terms  of this
Sublease.

In the event of a default in the payment of Additional Base Rental,  Sublandlord
shall have the same remedies as for a default in payment of Base Rental.

                  (C)  PAYMENT OF RENT.  Payment of Base  Rental and  Additional
Base Rental  (collectively  "Rent")  shall be paid in lawful money of the United
States  io  Sublandlord  "Attention:   David  N.  Bassett,  Vice  President  and
Treasurer"  at the address  designated  in Paragraph 17 hereof,  or as otherwise
designated  from time to time by written  notice from  Sublandlord to Subtenant.
The  obligation  to pay Rent  hereunder is  independent  of each and every other
covenant and agreement  contained in this Sublease  except as  specifically  set
forth herein.

                  (D)  LATE  PAYMENT.  All Rent not  paid  when due  shall  bear
interest  from the date due until paid at the rate of fifteen  percent (15%) per
annum or the highest  legal rate,  whichever  is lower (the  "Maximum  Rate" for
purposes of this Sublease and the Lease). In addition, if Subtenant fails to pay
any  installment of Rent within five (5) days from the date when due and payable
hereunder (or the date of notice thereof, in the case of non-regularly scheduled
payments of  Additional  Base Rental),  a late payment  penalty in the amount of
five  percent  (5%)  of  the  overdue  installment  shall  be  due  and  payable
immediately   by  Subtenant  to   Sublandlord,   as   Additional   Base  Rental.
Notwithstanding  the foregoing,  Sublandlord agrees to waive the first such late
payment penalty in each calendar year,  provided that  Sublandlord  receives the
overdue payment within five (5) days after written notice to Subtenant that such
payment is overdue.

         4. PERMITTED USE. Subtenant shall use and occupy the Subleased Premises
for general  office  purposes,  including a  computer/data  center and telephone
switch facility, and for no other use or purpose.

         5.  INCORPORATION  OF  LEASE.  Except  as  herein  otherwise  expressly
provided,  all of the  terms  of the  Lease  as they  pertain  to the  Subleased
Premises  are hereby  incorporated  into and made a part of this  Sublease as if
stated at length  herein,  and Subtenant  accepts this Sublease  subject to, and
hereby, during the Term of this Sublease, assumes all of the terms, covenants,

                                                     PG&E Generating Company and
                                                                  InforMax, Inc.
                                                     Sublease Agreement - Page 5

<PAGE>

conditions and  agreements  contained in the Lease with respect to the Subleased
Premises,  to be performed by Sublandlord  thereunder.  The parties hereto agree
that subject to the provisions of this Sublease,  wherever the words  "Premises"
or words of similar import appear in the Lease, the same shall be deemed to mean
the Subleased  Premises and wherever the words "Landlord" and "Tenant" appear in
the  Lease,  the words  shall be deemed to refer to  Sublandlord  and  Subtenant
respectively,  so that,  subject to the  provisions  of this  Sublease  and with
respect only to the Subleased  Premises,  Sublandlord  shall have the rights and
powers of the Landlord under the Lease, and Subtenant shall have and does hereby
agree to be bound by and accept all the rights,  powers,  duties and obligations
of the Tenant  under the Lease;  provided,  however,  that  notwithstanding  the
foregoing, Sublandlord shall have no obligation to perform or furnish any of the
work, services,  repairs or maintenance  undertaken to be made by Landlord under
the Lease, or any other term,  covenant or condition required to be performed by
Landlord  under the  Lease.  Subtenant  covenants  and  agrees  that it shall do
nothing  which  shall have the effect of  creating a breach of any of the terms,
covenants and conditions of the Lease.  In the event that Landlord shall fail or
refuse to comply with any of the respective provisions of the Lease, Sublandlord
shall have no liability on account of any such failure or refusal. Subtenant may
communicate  directly  with Landlord  and/or  Landlord's  management  agent with
respect to day-to-day  matters within the scope of services provided by Landlord
to, and for use and occupancy of, the Premises by Sublandlord under the terms of
the Lease.  Sublandlord  hereby  agrees to cooperate  with and  execute,  all at
Subtenant's expense, all instruments and supply information  reasonably required
by Subtenant in order to enforce such  compliance.  Subtenant  hereby  agrees to
indemnify  and  hold  Sublandlord  harmless  of and  from  any and all  damages,
liabilities,   obligations,   costs,  claims,  losses,  demands,  and  expenses,
including reasonable attorneys' fees, which may be incurred by Sublandlord in or
as a result of such  cooperation and execution,  unless caused by  Sublandlord's
negligence or willful misconduct.  In amplification and not in limitation of the
foregoing  and  without  any  allowance  to  Subtenant  or  other  reduction  or
adjustment  of  Rent,  Sublandlord  shall  not  be  responsible  for  furnishing
electrical,  elevator,  heating, air conditioning,  cleaning, window washing, or
other  services,  nor for any  maintenance  or  repairs  in or to the  Subleased
Premises or the  Building of which it is a part or to any of the  facilities  or
equipment therein;  provided,  however,  for any period during which Sublandlord
receives an abatement of Rent under Section 7.B of the Lease due to a failure of
Landlord to provide  services,  Subtenant shall receive an abatement of the Rent
due under this Sublease.

         The  following  sections of the Lease shall not be  applicable  to this
Sublease: 1A(1), 1A(2), 1A(4), 1A(5), 1A(6), 1A(7), 1A(8), 1B(1), 1(B(2), 1B(4),
1B(6), 1B(12), 1B(14) 1B(15),  1B(17),  1B(20),  1B(21), 1B(25), 1B(26), 1B(32),
1B(34),  1B(35),  1B(37) and 1B(38) (Basic Lease  Information;  Definitions);  3
(Term);  4A,  4B,  4C, 4F,  4H,  4I, 4J and 4K  (Rent);  6  (Storage  Space);  9
(Graphics);  the last three  sentences of 10A, the last  sentence of 10B and the
first sentence of 10C (Repairs and Alterations); 11A and the first two sentences
of 11 B (Electrical Services); 13A (Assignment and Subletting);  15 (Indemnity);
16A and  16D  (Tenant's  Insurance);  the  last  sentence  of  18A,  18B and 18C
(Landlord's Insurance); 28 (Construction of the Premises); the second, third and
fourth  paragraphs  of 30  (Subordination);  34  (Access to Roof);  37  (Parking
Garage); the last sentence of 38 (Access);  39 (Option to Extend); 40 (Expansion
Space); 41F, 41I,41O and 41P (Miscellaneous); 42 (Right of First Offer); Exhibit
D  (Commencement  Letter);  Exhibit E (Outline and  Location of Storage  Space);
Exhibit G (Schedule of Base Building Plans and Specifications);  Exhibit H (Form
of Guaranty);  Exhibit I (Title  Insurance  Policy and  Commitment on Property);
Exhibit J (Construction Schedule);  Exhibit K (Schedule of Base Rental); Exhibit
L (Schedule of Insurance Deductibles); and Exhibit M (Work Letter).

         6.  TRANSMITTAL  OF NOTICES AND  DEMANDS.  Sublandlord  shall  promptly
transmit to Landlord  any notice or demand  received  from  Subtenant  and shall
promptly  transmit to Subtenant  any notice or demand  received  from  Landlord.
Subtenant  shall promptly  transmit to Sublandlord any notice or demand received
from Landlord or any other party relating to the Subleased Premises.

                                                     PG&E Generating Company and
                                                                  InforMax, Inc.
                                                     Sublease Agreement - Page 6

<PAGE>

         7.  LANDLORD'S  CONSENT TO CERTAIN ACTS.  Subtenant  agrees that in any
case where the  provisions of the Lease or this Sublease  require the consent or
approval of Landlord prior to the taking of any action,  it shall be a condition
precedent  to the taking of such  action  that the prior  consent or approval of
Landlord shall have been obtained.  Subtenant agrees that Sublandlord  shall not
have any duty or  responsibility  with  respect  to  obtaining  the  consent  or
approval  of Landlord  when the same is  required  under the terms of the Lease,
other than the  transmission  by Sublandlord to Landlord of Subtenant's  request
for such consent or approval.

         8. SUBLANDLORD'S RIGHT TO CURE SUBTENANT'S DEFAULT. Subtenant shall not
do or suffer or permit  anything  to be done which  would  cause the Lease to be
terminated  or forfeited by virtue of any rights of  termination  or  forfeiture
reserved  or vested in  Landlord  or by law or in  equity.  If  Subtenant  shall
default beyond the expiration of any applicable  cure period in the  performance
of any of its obligations  under this Sublease or under the Lease,  Sublandlord,
without  being under any  obligation to do so and without  thereby  waiving such
default, may remedy such default for the account and at the expense of Subtenant
upon  prior  notice.  If  Sublandlord  makes  any  expenditures  or  incurs  any
obligation for the payment of money in connection  therewith,  such sums paid or
obligations  incurred shall be deemed to be Additional  Rent hereunder and shall
be paid to Sublandlord by Subtenant on demand.

         9.       UTILITIES.

                  (A) OVERTIME  HEATING AND AIR  CONDITIONING.  Should Subtenant
require  heating or cooling  services  beyond the Normal  Business Hours for the
Building  stipulated in Section  1B(23) of the Lease,  Sublandlord  will furnish
such additional  service at the  then-prevailing  hourly rate, as established by
Sublandlord from time to time, provided that Subtenant gives Sublandlord no less
than forty-eight (48) hours advance written notice of the need therefor.

                  (B) EXCESSIVE ELECTRICAL USE. If Sublandlord believes (i) that
the Subleased  Premises,  and portion  thereof,  or any electrical  equipment or
machinery  therein,  is consuming or will consume  electricity  in excess of 1.5
watts per square foot for lighting  (exclusive of the electric  power needed for
the  Building  MEP  systems)  and/or 5 watts  per  square  foot for  receptacles
(exclusive of the electric  power needed for the Building MEP systems),  or (ii)
that the Subleased Premises, and portion thereof, or any electrical equipment or
machinery  therein,  is consuming or will consume  electricity for significantly
more hours per week than is standard for normal office use, then Sublandlord may
require that the Subleased Premises or such portion thereof or such equipment or
machinery   therein  be  separately   metered  or  submetered  for   electricity
consumption.  The cost of any such meters and of  installation,  maintenance and
repair thereof shall be paid by Subtenant.  Subtenant  agrees to pay Sublandlord
or  Landlord  (or the  utility  company,  if direct  service is  provided by the
utility  company),  promptly  upon  demand  therefor,  for all such  electricity
consumption  as shown by said meters,  at the rates  charged for such service by
the local public utility company.

         10.      ASSIGNMENT OF SUBLEASE.

                  (A)  Subtenant  shall not assign,  mortgage  or encumber  this
Sublease,  nor sublet,  nor suffer or permit the Subleased  Premises or any part
thereof  to be used by others  (any of which  events is  hereinafter  and in the
Lease  referred to as a  "Transfer"),  except with the prior written  consent of
Sublandlord and Landlord, which consent may be granted or withheld in their sole
discretion,  except as otherwise set forth in Paragraphs 10(b), 10(c) and 10(d).
Any attempted Transfer in violation of this provision shall be void. In no event
shall any Transfer,  including  without  limitation a Transfer  permitted  under
Paragraph 10(b) below,  relieve Subtenant of its liability and responsibility to
Sublandlord under this Sublease or to Landlord under the Lease in the absence of
any express written agreement with Sublandlord or Landlord,  as the case may be,
to that effect.

                                                     PG&E Generating Company and
                                                                  InforMax, Inc.
                                                     Sublease Agreement - Page 7

<PAGE>

                  (B) Provided  that  Subtenant  is not then in default,  and is
then (and after the commencement of the proposed  sublease will be) occupying at
least seventy-five percent (75%) of the Subleased Premises, Subtenant shall have
the right to sublet up to  twenty-five  percent (25%) of the Subleased  Premises
with the prior written consent of Sublandlord and Landlord,  WHICH consent shall
not be unreasonably withheld, conditioned or delayed, provided that the proposed
subtenant is  comparable  to other  tenants of first class  office  buildings in
Bethesda, Maryland.

                  (C) In the event  Subtenant  desires to sublet any part of the
Subleased  Premises,  and the  part of the  Subleased  Premises  proposed  to be
sublet,  together with the parts of the Subleased Premises  previously sublet by
Subtenant,  constitutes  more than  twenty-five  percent  (25%) of the Subleased
Premises,  Subtenant  shall give  Sublandlord  and  Landlord  written  notice of
Subtenant's  desire to do so.  Within sixty (60) days of receipt of said notice,
Sublandlord  shall have the right to terminate this Sublease with respect to the
portion  of  the  Subleased  Premises  that  Subtenant  desires  to  sublet.  If
Sublandlord  fails to  exercise  such right,  Subtenant  shall have the right to
sublet such portion of the Subleased  Premises with the prior written consent of
Sublandlord  and Landlord,  which consent  shall not be  unreasonably  withheld,
provided that  Subtenant is not then in default and that the proposed  subtenant
is  comparable  to other  tenants of first class  office  buildings in Bethesda,
Maryland;  provided,  however,  that Subtenant shall pay to Sublandlord  monthly
fifty  percent  (50%) of the "Net  Profits"  (as  defined  herein)  received  by
Subtenant in  connection  with such  sublease.  "Net  Profits" is defined as the
excess of the rent  and/or all other sums  collected  by  Subtenant  under or in
connection  with such  sublease  over and above the Rent payable by Subtenant to
Sublandlord  under this Sublease for the space  covered by such sublease  (which
shall be the pro rata  portion  of the total  Rent  payable  hereunder)  and the
direct,  out of pocket costs incurred by Subtenant in performing  alterations or
leasehold improvements for the assignee or subtenant and the leasing commissions
paid,  and rental  abatement  granted,  by  Subtenant  in  connection  with such
assignment or sublease.

                  (D) Notwithstanding anything to the contrary herein, Subtenant
may assign this Sublease or sublet all or part of the Subleased  Premises either
to a wholly owned  corporation  or entity or controlled  subsidiary or parent of
the   Subtenant  or  to  any   successor  to  Subtenant  by  purchase,   merger,
consolidation  or  reorganization   (hereinafter  collectively  referred  to  as
"Corporate Transfer") without the consent of Sublandlord or Landlord and without
being subject to Sublandlord's  rights under Paragraph 10(c),  provided that (i)
Subtenant  is  not in  default  under  this  Sublease;  (ii)  if  such  proposed
Transferee  is a successor to Subtenant by purchase,  said  proposed  Transferee
shall  acquire all or  substantially  all of the stock or assets of  Subtenant's
business or, if such proposed  Transferee is a successor to Subtenant by merger,
consolidation or reorganization,  the continuing or surviving  corporation shall
own all or  substantially  all of the assets of Subtenant;  (lii) such Corporate
Transfer shall be subject to the terms of this Sublease;  (iv) in the case of an
assignment, such proposed Transferee shall have a net worth which is equal to or
greater than Subtenant's net worth at the date of this Sublease;  and (v) in the
case of an assignment, such proposed Transferee shall assume all the obligations
of Subtenant  hereunder.  Subtenant shall give  Sublandlord and Landlord written
notice  at  least  thirty  (30)  days  prior to the  effective  date of any such
Corporate Transfer. As used herein, the term "controlled  subsidiary" shall mean
a corporate entity wholly owned by Subtenant or at least fifty-one percent (51%)
of whose voting stock is owned by Subtenant.

         11. ALTERATIONS TO SUBLEASED PREMISES. Subtenant covenants at all times
during  the Term not to make  any  alterations  or  additions  to the  Subleased
Premises  of  any  nature  whatsoever  without  the  prior  written  consent  of
Sublandlord  and Landlord,  which consent  shall not be  unreasonably  withheld,
conditioned or delayed for  nonstructural,  interior  alterations.  In the event
Subtenant  obtains  Sublandlord's  and  Landlord's  consent  and  all  necessary
governmental approvals and permits,  Subtenant shall have the right to make such
alterations at Subtenant's  sole expense.  All alterations and additions made by
Subtenant to the Subleased Premises shall remain upon the

                                                     PG&E Generating Company and
                                                                  InforMax, Inc.
                                                     Sublease Agreement - Page 8

<PAGE>

Subleased  Premises  and be  surrendered  with  the  Subleased  Premises  at the
expiration  of the Term  without  disturbance,  molestation  or  injury,  unless
otherwise  specified by Sublandlord or Landlord.  Should Sublandlord or Landlord
elect,  at the time of consenting to any  alterations or additions to be made by
Subtenant  upon the  Subleased  Premises,  that such  alteration or additions be
removed upon the expiration of the Term,  Subtenant  agrees that  Sublandlord or
Landlord  shall have the right to cause same to be removed at  Subtenant's  sole
cost and expense.  Subtenant agrees to reimburse Sublandlord or Landlord for the
cost of such removal and repairing any damage resulting therefrom.

          12.     SIGNAGE.

                  (A) DIRECTORY AND SUITE ENTRANCE SIGNS.  Sublandlord agrees to
display,  at  Subtenant's  expense,  Subtenant's  name and  other  listings  for
Subtenant on the  Building  directory  or  directories  in the size and style or
lettering  used by  Sublandlord.  The number of  individual  names listed on the
Building  directory or  directories  for Subtenant  shall,  after  deducting the
portion of the directory used by  Sublandlord,  be proportional to percentage of
portion of the  Building  not  occupied by  Sublandlord,  which is  subleased by
Subtenant.  Subtenant  may display its name on the corridor wall adjacent to the
Subleased Premises, as directed by Sublandlord, in Building standard color, size
and style of lettering, to be furnished by Sublandlord at Subtenant's expense.

                  (B) CONSENT REQUIRED.  No sign,  advertisement or notice shall
be  inscribed,  painted,  affixed or displayed on any part of the outside or the
inside of the  Building,  or inside of the  Subleased  Premises  where it may be
visible from outside or from the public areas of the  Building,  except with the
prior  written  consent of  Sublandlord  and  Landlord,  which may be granted or
withheld in their sole discretion, and then only in such location, number, size,
color and style as is authorized by Sublandlord and Landlord.  If any such sign,
advertisement or notice is exhibited  without first obtaining  Sublandlord's and
Landlord's written consent, Sublandlord shall have the right to remove same, and
Subtenant  shall be liable for any and all expenses  incurred by  Sublandlord in
connection with said removal.

         13. INDEMNITY. Except for the negligent or willful acts or omissions of
Landlord, its members, principals, beneficiaries, partners, officers, directors,
employees, Mortgagee(s) and agents, and the respective principals and members of
any such agents (collectively, the "Landlord Related Parties"), Sublandlord, and
its members, principals, beneficiaries, partners, officers, directors, employees
and  agents,  and the  respective  principals  and  members  of any such  agents
(collectively,  the "Sublandlord  Related Parties"),  Subtenant shall indemnify,
defend and hold Landlord,  the Landlord  Related  Parties,  Sublandlord  and the
Sublandlord   Related  Parties   harmless  against  and  from  all  liabilities,
obligations,   damages,   penalties,   claims,   costs,   charges  and  expenses
(collectively,  "Claims"), including, without limitation,  reasonable attorneys'
fees and other  professional fees (if and to the extent permitted by law), which
may be imposed  upon,  incurred  by, or asserted  against  Landlord,  any of the
Landlord Related Parties,  Sublandlord or any of the Sublandlord Related Parties
that (1) arise from or in connection with the possession, occupancy, management,
repair,  maintenance  or  control  of the  Subleased  Premises,  or any  portion
thereof,  by Subtenant or any party claiming by, through or under Subtenant,  or
(2) arise from or in  connection  with any act or omission by  Subtenant  or any
party claiming by, through or under Subtenant in the Limited Common Areas of the
Building (defined, for purposes of this Sublease and the Lease,  notwithstanding
anything to the contrary in the Lease,  as those areas of the Building  provided
for the common use or benefit of Sublandlord, Subtenant, the other subtenants of
the Building and Landlord, such as corridors,  elevator foyers, restrooms, lobby
areas,  loading docks and other  similar  facilities)  including,  to the extent
applicable under this  subparagraph  (2), all such Claims resulting by reason of
any injury or death to persons  or damage to  property,  or (3) arise from or in
connection  with any willful or negligent act or omission of Subtenant or any of
its transferees, agents, servants, contractors,  employees, customers, licensees
or invitees, or (4)

                                                     PG&E Generating Company and
                                                                  InforMax, Inc.
                                                     Sublease Agreement - Page 9

<PAGE>

result from any failure on the part of  Subtenant  to perform or comply with any
of the covenants, agreements, terms or conditions contained in the Lease or this
Sublease with which  Subtenant must comply or perform,  or (5) arise from injury
or death to persons or damage to property sustained in the Subleased Premises or
any other  space  leased to  Subtenant  in the  Building.  In case any action or
proceeding is brought against  Landlord,  any of the Landlord  Related  Parties,
Sublandlord or any of the  Sublandlord  Related  Parties by reason of any of the
foregoing,  Subtenant  shall, at Subtenant's  sole cost and expense,  resist and
defend  such  action  or  proceeding  with  counsel  approved  by  Landlord  and
Sublandlord,  or at Landlord's and Sublandlord's option,  reimburse Landlord and
Sublandlord  for the cost of any  counsel  directly  retained  by  Landlord  and
Sublandlord to defend and resist such action or proceeding.

         14.  SUBTENANT'S  INSURANCE.  At all times  commencing  on or after the
earlier  of the  Preliminary  Commencement  Date or the  date  Subtenant  or its
agents,  employees or contractors enters the Subleased Premises for any purpose,
Subtenant shall carry and maintain, at its sole cost and expense:

                  (1) Commercial General Liability  Insurance  applicable to the
Subleased Premises, providing, on an occurrence basis, a minimum combined single
limit of Two  Million  Dollars  ($2,000,000.00),  with a  contractual  liability
endorsement covering Subtenant's  indemnity  obligations under this Sublease and
the Lease.

                  (2) All Risk of Physical Loss Insurance written at replacement
cost value and with a replacement cost  endorsement  covering all of Subtenant's
Property in the Subleased Premises.

                  (3) Workers'  Compensation  Insurance as required by the state
in which the Subleased  Premises is located and in amounts as may be required by
applicable  statute,  and Employers'  Liability  Coverage of One Million Dollars
($1,000,000.00) per occurrence.

                  (4) Whenever  Landlord  requires  Tenant to obtain  additional
insurance  coverage  or  different  types of  insurance  pursuant  to the Lease,
Subtenant shall, upon request,  obtain such insurance at Subtenant's expense and
provide Sublandlord with evidence thereof.

The  requirements of Section 16C of the Lease shall apply to all insurance which
Subtenant is required to maintain pursuant to the terms of this Sublease.

         15.  EMINENT  DOMAIN,  LOSS BY CASUALTY.  In the event of any taking by
eminent  domain or damage by fire or other  casualty to the  Subleased  Premises
thereby  rendering  the  Subleased  Premises  wholly  or in  part  untenantable,
Subtenant  shall  acquiesce  in and be bound by any action taken by or agreement
entered into between Landlord and Sublandlord with respect thereto.

         16.      DEFAULT.

                  (A) EVENTS OF  DEFAULT.  In  addition to the events of default
set forth in Section 22 of the Lease,  the following event shall be deemed to be
events of default under this Sublease:

                           (i) A Transfer in violation of Paragraph 10; or

                           (ii)   Subtenant's   abandonment   of  the  Subleased
Premises for more than thirty (30) consecutive days.

Notwithstanding  anything  to the  contrary  in  subsection  22A  of the  Lease,
Sublandlord  shall  not be  required  to give  Subtenant  more than two (2) such
notices in any twelve (12) month period.

                                                     PG&E Generating Company and
                                                                  InforMax, Inc.
                                                    Sublease Agreement - Page 10

<PAGE>

                  (B)  REMEDIES.  If  this  Sublease  or  Sublessee's  right  to
possession  of the  Subleased  Premises  is  terminated  because  of an event of
default,  Sublandlord  shall have all of the remedies set forth in Section 23 of
the Lease.

         17.  NOTICE AND  DEMANDS.  All notices or demands  under this  Sublease
shall be in writing  and shall be sent by  overnight  courier  service  (such as
Federal Express), or registered or certified mail, return receipt requested,  or
hand  delivered,  to the following  addresses or such other address as either of
the parties may designate by written notice:

         If To Sublandlord:               PG&E Generating Company
                                          7500 Old Georgetown Road
                                          13th Floor
                                          Bethesda, Maryland 20814
                                          Attn: P. Chrisman Iribe,
                                                PCI President

         with a copy to:                  PG&E Generating Company
                                          7500 Old Georgetown Road
                                          13th Floor
                                          Bethesda, Maryland 20814
                                          Attn: Stephen Herman, Esquire,
                                                   General Counsel

         If To Subtenant:                 Before occupancy of Subleased
                                            Premises:

                                          InforMax, Inc.
                                          6010 Executive Boulevard
                                          Rockville, Maryland 20852

                                          After occupancy of Subleased Premises:

                                          InforMax, Inc.
                                          7600 Wisconsin Avenue
                                          10th Floor
                                          Bethesda, Maryland 20814

  With a copy (in either case) to:        Hogan & Hartson L.L.P.
                                          8300 Greensboro Drive
                                          Suite 1100
                                          McLean, Virginia 22102
                                          Attn:  Dennis K. Moyer, Esquire

All  notices  hereunder  shall be  effective  when  delivered  in  person  or by
overnight courier service, as indicated on the receipt obtained by the messenger
or overnight delivery service,  or three (3) business days after mailing, as the
case may be.

         18.  SURRENDER  OF SUBLEASED  PREMISES.  Upon the  expiration  or other
termination  of  the  Term,   Subtenant  covenants  to  quit  and  surrender  to
Sublandlord  or  Landlord,  as the case may be, the  Subleased  Premises,  broom
clean,  in good order and  condition,  ordinary  wear and tear damage by fire or
other casualty  excepted,  and at Subtenant's  expense to remove all property of
Subtenant. Any property not so removed shall be deemed to have been abandoned by
Subtenant

                                                     PG&E Generating Company and
                                                                  InforMax, Inc.
                                                    Sublease Agreement - Page 11

<PAGE>

and may be  retained or disposed of at  Subtenant's  expense by  Sublandlord  or
Landlord, as either may desire.

         19.  PARKING.  Subtenant  shall  have  the  right  to use up to two (2)
parking spaces in the Building  parking garage per one thousand (1,000) rentable
square feet of floor space in the Subleased Premises; provided, however, that if
Subtenant  does  not  commence  using  all  such  parking  spaces  on  the  Rent
Commencement  Date,  or  ceases  using  all  such  parking  spaces  at any  time
thereafter,  Subtenant  shall  thereafter  have the  right to use the  remaining
parking  spaces  allocated to Subtenant only to the extent there are then unused
parking spaces in the Building  parking garage.  For each month during the Term,
Subtenant  shall  pay to  Sublandlord,  as  Additional  Rent for the use of such
parking spaces, an amount equal to the product obtained by multiplying:  (i) the
number of parking spaces  utilized by Subtenant in this  paragraph,  by (ii) the
market rent for each such space,  as  determined  from time to time by Landlord,
Sublandlord  and/or the garage operator.  On the Rent Commencement Date the rent
for each such space shall be One Hundred and No/100 Dollars ($100.00) per month.
No specific  parking spaces shall be designated for use by Subtenant;  provided,
however,  that if  Sublandlord  or  Landlord  institutes  reserved  parking  for
subtenants of the Building,  then at Subtenant's  option,  up to four (4) of the
parking spaces  allocated to Subtenant above shall be designated as reserved for
Subtenant and the rent for each such reserved space shall be the market rent for
a reserved  space,  as  determined  from time to time by  Landlord,  Sublandlord
and/or the garage operator.  Subtenant  acknowledges that Landlord has the right
to institute either a valet or self-parking system.

         20.  BROKERAGE  FEES. The parties hereto  represent and warrant to each
other that they have not dealt with any broker other than Jones Lang LaSalle USA
and  The  Bank  Companies.  Sublandlord  shall  pay  said  brokers  a  brokerage
commission pursuant to a separate agreement between Sublandlord and said brokers
in connection with this Sublease. Each party hereto agrees to indemnify,  defend
and  hold the  other  party  harmless  against  any  claim  or  liability  for a
commission  by any  broker,  arising  by reason of a breach by the  indemnifying
party of the aforesaid representation and warranty.

         21.  AUTHORITY  TO EXECUTE  LEASE.  Each of Subtenant  and  Sublandlord
represents  and warrants that this Sublease has been duly  authorized,  executed
and  delivered  by and on behalf of such  party  and  constitutes  the valid and
binding agreement of such party in accordance with the terms hereof.

         22.     SECURITY DEPOSIT.

                  (A)  Subtenant  has  deposited  with  Sublandlord   before  or
simultaneously with the execution of Sublease,  a cash deposit or an irrevocable
and  unconditional  letter  of  credit,  in form and  substance  and with a bank
satisfactory  to  Landlord,  in the amount of Four  Hundred  Sixty  Thousand Two
Hundred  and  No/100  Dollars  ($460,200.00)  as a deposit  to secure the prompt
performance  of  Subtenant's  obligations  hereunder.  On or before the Delivery
Date,  Subtenant shall deposit with Sublandlord a cash deposit or an irrevocable
and  unconditional  letter  of  credit,  in form and  substance  and with a bank
satisfactory  to Landlord,  in the amount of Nine Hundred  Twenty  Thousand Four
Hundred and No/100 Dollars  ($920,400.00) as an additional deposit to secure the
prompt  performance  of  Subtenant's  obligations  hereunder.  In the event that
Subtenant  fails to provide  Landlord with such  additional  Nine Hundred Twenty
Thousand Four Hundred and No/100 Dollar  ($920,400.00)  deposit on or before the
Delivery Date, then this Sublease shall automatically  terminate on the Delivery
Date,  Sublandlord  shall retain the Four Hundred Sixty Thousand Two Hundred and
No/100 Dollar ($460,200.00)  deposit as full and complete liquidated damages for
Subtenant's failure to deliver such additional deposit, Sublandlord shall return
any advance  Rent  payment to  Subtenant,  and the parties  shall  thereupon  be
relieved of any and all further liability under this Sublease.

                                                     PG&E Generating Company and
                                                                  InforMax, Inc.
                                                    Sublease Agreement - Page 12

<PAGE>

                  (B) If Subtenant provides cash deposits,  such deposits may be
commingled with  Sublandlord's  general funds, if permitted by law.  Sublandlord
shall have the right, but shall not be obligated, to apply all or any portion of
such deposits to cure any default,  in which event  Subtenant shall be obligated
to deposit with  Sublandlord  the amount  necessary to restore such  deposits to
their   original   amount  within  five  (5)  days  after  written  notice  from
Sublandlord.  To the extent not forfeited or otherwise used as provided  herein,
and provided the Subleased Premises are vacated in good condition, ordinary wear
and  tear and  damage  by fire or  other  casualty  excepted,  as  described  in
Paragraph 18, the deposits  shall be returned,  without  interest,  to Subtenant
within  thirty  (30) days  after the  expiration  or other  termination  of this
Sublease.

                  (C) If Subtenant  provides letters of credit,  said letters of
credit shall be issued by a commercial bank satisfactory to Sublandlord,  having
banking  offices  at which  said  letters  of  credit  may be drawn  upon in the
Washington, D.C. metropolitan area, and a net worth of not less that One Billion
Dollars.  Said letters of credit shall be subject to the  International  Standby
Practices 1998, International Chamber of Commerce Publication No. 590, and shall
be  transferable  one or more  times  by  Sublandlord  without  the  consent  of
Subtenant.  Any  transfer  fees in  connection  therewith  shall be  payable  by
Subtenant.  Sublandlord  hereby  approves  PNC Bank as the issuing bank for said
letters of credit. Sublandlord shall have the right, but shall not be obligated,
to draw down all or any  portion of said  letters of credit to cure any event of
default which continues beyond the expiration of any applicable cure period. The
letter of credit  shall  provide that it may be drawn down by  Sublandlord  upon
presentation  of  Sublandlord's  draft drawn on the issuing bank. If, during the
Preliminary Term or during any Sublease Year,  Sublandlord  draws down more than
twenty-five  percent  (25%) of the original  aggregate  amount of the letters of
credit,  then  Subtenant,  within  fifteen (15) days after  written  notice from
Sublandlord,  shall provide Landlord with an additional  letter of credit in the
amount of the difference between the original aggregate amount of the letters of
credit and the  then-current  balance  thereof.  Not less than  thirty (30) days
prior  to the  expiration  date of any  letter  of  credit  provided  hereunder,
Subtenant shall provide  Sublandlord with a replacement  letter of credit in the
same amount (or such lesser amount as may be required under  subparagraph  22(d)
(except that if Subtenant does not exercise its renewal option with Landlord, no
such replacement  letter of credit shall be required after the expiration of the
twelfth (12th)  Sublease Year, and if Subtenant does exercise its renewal option
with Landlord,  the  replacement  letter of credit required at the expiration of
the twelfth  (12th)  Sublease  Year shall be deposited  with  Landlord and shall
provide that it may be drawn down by Landlord  upon  presentation  of Landlord's
draft  drawn on the issuing  bank).  Each  letter of credit  provided  hereunder
(except,  if Subtenant does not exercise its renewal option with Landlord,  that
provided  during the twelfth  (12th)  Sublease  Year) shall  provide that in the
event it is not  supplemented by a replacement  letter of credit or cash deposit
on or before thirty (30) days prior to its expiration, then Sublandlord may draw
down the full  amount of such  letter of credit.  Sublandlord  agrees that if it
draws down a letter of credit due solely to a failure of Subtenant to so provide
a replacement  letter of credit,  Sublandlord shall hold the proceeds of same in
an interest-bearing  account with a financial institution that is insured by the
FDIC or any  federal  successor  thereto,  until  the  sooner  to  occur  of (i)
Subtenant's provision of such a replacement letter of credit, at which time such
proceeds shall be paid to Subtenant, or (ii) an event of default by Subtenant of
one or more of its obligations  under this Sublease which  continues  beyond the
expiration  of any  applicable  cure  period,  at which time  Sublandlord  shall
withdraw  proceeds  in  an  amount  equal  to  the  economic  loss  suffered  by
Sublandlord as a result of such event of default, and the remaining proceeds (if
any) shall  continue to be held in such  account  pursuant to the terms  hereof.
Notwithstanding  the foregoing,  if Subtenant  exercises its renewal option with
Landlord, and Sublandlord draws down on the letter of credit provided during the
twelfth  (12th)  Sublease Year due solely to a failure of Subtenant to provide a
replacement  letter of credit,  then Sublandlord  shall pay the proceeds of such
letter of credit to Landlord,  to be held in  accordance  with the terms of this
paragraph.   Subtenant  hereby  agrees  to  cooperate,   at  its  expense,  with
Sublandlord  to  promptly  execute  and  deliver  to  Sublandlord  any  and  all
modifications,   amendments  and  replacements  to  the  letters  of  credit  as
Sublandlord may reasonably request to carry out the terms and conditions of this
Paragraph 22(c).

                                                     PG&E Generating Company and
                                                                  InforMax, Inc.
                                                    Sublease Agreement - Page 13

<PAGE>

                  (D) Notwithstanding anything to the contrary herein, Subtenant
may reduce the amount of the cash or letter of credit security  deposit provided
hereunder  to Six Hundred  Ninety  Thousand  Three  Hundred  and No/100  Dollars
($690,300.00)  [i.e.,  six (6) times the initial monthly Base Rental],  provided
that Subtenant  gives  Sublandlord not less than thirty (30) days written notice
of its intent to so reduce the security deposit,  which notice is accompanied by
Subtenant's most recent annual audited financial  statement,  and a year-to-date
financial statement certified as correct by Subtenant's Chief Financial Officer,
both of which financial  statements  show cash and cash  equivalents of at least
Five Million  Dollars  ($5,000,000.00)  and  earnings  before  interest,  taxes,
depreciation and amortization of at least One Million Dollars ($1,000,000.00).

                  (E) Sublandlord,  in its sole discretion, may permit Subtenant
to  replace  all or part of the cash or letter of credit  deposits  with a bond,
provided that the bond issuer's  creditworthiness and experience as a surety and
the form of the bond are acceptable to Sublandlord, in its sole discretion.

                  (F) Sublandlord may deliver the cash, letter of credit or bond
deposits to any assignee of Sublandlord's  interest in this Sublease,  whereupon
Sublandlord  shall be discharged from any further liability with respect to such
deposits.  This provision shall apply also to any and all subsequent transferors
of the Sublandlord's interest in this Sublease.

         23.     SUBTENANT'S ROOF USE.

                  (A)  Throughout  the Term,  Subtenant  shall have the right to
install and maintain,  subject to applicable laws and  governmental  regulations
and the  provisions  of this  Paragraph  23,  one or more  satellite  or antenna
dishes,  solely for Subtenant's use in the operation of its primary business, on
an area or areas in locations mutually and reasonably  acceptable to Sublandlord
and  Subtenant   and  approved  by  Landlord,   on  the  roof  of  the  Building
("Subtenant's Roof Use").  Subtenant shall screen such installations in a manner
mutually  acceptable to Landlord,  Sublandlord  and Subtenant.  Subtenant  shall
remove any such satellite or antenna  dishes and any related  equipment from the
Building at the  expiration or other  termination  of the Term of this Sublease,
and Subtenant shall, at its sole cost and expense, make all necessary repairs or
restoration  occasioned  by such removal and restore any portion of the Building
affected by the  installation  of the  satellite  or antenna  dishes and related
equipment to its original  condition.  Subtenant shall pay all costs  associated
with the installation,  maintenance,  repair, use, insurance and removal of such
satellite or antenna dishes and any related  equipment.  Subtenant may use up to
fifty (50) square feet of space on the roof of the Building for Subtenant's Roof
Use  without  the  payment of rent  therefor  to  Sublandlord  or  Landlord.  If
Subtenant  requires more than fifty (50) square feet of space on the roof of the
Building for Subtenant's Roof Use, Sublandlord and Landlord reserve the right to
charge  Subtenant  rent for the roof space in excess of fifty (50)  square  feet
used for Subtenant's  Roof Use.  Subtenant shall not assign or sublet any of its
rights under this Paragraph 23 to any other party.

                  (B) Subtenant shall give Landlord reasonable telephonic notice
before any entry onto the roof of the Building by Subtenant's agents,  employees
or  contractors,  and shall permit  Landlord's  agents or employees to accompany
Subtenant's  agents,  employees or  contractors on any such entry onto the roof.
Landlord and Sublandlord  shall not be liable for any claims,  losses,  actions,
damages, liabilities or expenses arising from any satellite or antenna dishes or
related  equipment  installed by Subtenant on the roof of the  Building,  or the
installation,  maintenance,  repair,  use or removal of such  dishes and related
equipment.

                  (C)  Subtenant  shall  obtain   Sublandlord's  and  Landlord's
written  consent prior to  installation  of any  satellite or antenna  dishes or
other  roof-top  equipment,   with  respect  to  the  type,  weight,  method  of
installation and appearance of all such items. Sublandlord and Landlord shall be
entitled to condition its consent to the  installation  of such load supports as
Sublandlord or

                                                     PG&E Generating Company and
                                                                  InforMax, Inc.
                                                     Sublease Agreement- Page 14

<PAGE>

Landlord may  reasonably  determine  necessary to support the proposed  roof-top
equipment.  Subtenant  shall  provide  Sublandlord  and Landlord  with plans and
specifications  sufficient  for such  purposes.  Subtenant  will obtain prior to
installation,  any and all governmental  licenses,  approvals  necessary for the
installation,  maintenance and use of any equipment  installed  pursuant to this
Paragraph  23.  Subtenant's  Roof Use  shall  not in any way  conflict  with any
applicable laws or governmental regulations.  Subtenant shall indemnify and hold
Sublandlord  and  Landlord  harmless  from and  against  any and all loss,  cost
(including  reasonable  attorney's  fees incurred in defending  Sublandlord  and
Landlord),  damage or liability arising out of any violation by Subtenant's Roof
Use of any applicable  laws.  The provisions  contained in Sections 10 and 16 of
the Lease shall fully govern all roof-top installations by Subtenant hereunder.

                  (D)  Subtenant's  Roof  Use  shall be  exercised:  (i) in such
manner as will not create any  hazardous  condition or interfere  with or impair
the  operation  of  the  heating,   ventilation,  air  conditioning,   plumbing,
electrical, fire protection,  life, safety, public utilities or other systems or
facilities  in the  Building;  (ii) in such a manner  as will  not  unreasonably
interfere  with  Landlord's  operation  or  maintenance  of the  Building or the
operations of other tenants of the Project; (iii) at Subtenant's cost, including
the cost of repairing any damage to the Building and any personal  injury and/or
property damage caused by the installation, inspection, adjustment, maintenance,
removal or replacement of any of Subtenant's  equipment on the roof; and (iv) in
a manner which will not void or invalidate any roof warranty then in effect with
respect to the roof of the Building. Subtenant, at its expense, shall use a roof
contractor  approved  by  Landlord  to seal any roof  penetration  caused by the
installation,  maintenance  or removal of  Subtenant's  equipment  and Subtenant
shall be  responsible  for all roof repairs  necessitated  by the  installation,
maintenance, use or removal of such equipment,  including any roof repairs which
would  have  been  covered  by a  warranty  lost by  reason  of any of the same.
Subtenant  shall  eliminate,   to  the  extent  possible,   any  electromagnetic
interference with the equipment of Landlord, Sublandlord and other subtenants of
the  Building  caused by  Subtenant's  satellite  or antenna  dishes and related
equipment.

                  (E) To the extent  that  Subtenant  shall  cause any wiring or
cabling (including, without limitation, any and all supporting structures) to be
installed,  pulled or operated in the  Subleased  Premises  (including,  without
limitation, any telecommunications  equipment installed by reason of Subtenant's
Roof Use) such wiring or cabling, and supporting structures at Landlord's option
shall be removed (provided  Landlord advised Subtenant in writing at the time of
its consent to the  installation  of such wiring and cabling that such items are
to be removed) and the Building  restored by  Subtenant at  Subtenant's  expense
upon  expiration or earlier  termination  of this Sublease.  The  obligations of
Subtenant under this Paragraph  23 shall expressly  survive such  termination or
expiration of this Lease.

         24.     RIGHT OF FIRST OPPORTUNITY.

                  (A) OPTION AND  EXERCISE.  If the second  (2nd) or third (3rd)
floor of the Building  (each, an "Expansion  Floor") shall become  available for
subletting at any time during the Term,  then provided that  Subtenant is not in
default and is occupying at least  seventy-five  percent  (75%) of the Subleased
Premises,  Subtenant  shall have a right of first  opportunity  to sublease  the
entire such Expansion Floor (but not less than the entire such Expansion  Floor)
for the then-remaining Term of this Sublease, upon the same terms, covenants and
conditions as set forth in this Sublease with respect to the Subleased Premises,
except that (i) the Rent  Commencement Date for the Expansion Floor shall be the
date on which  Sublandlord  delivers  possession  of the  Subleased  Premises to
Subtenant  in its "as is"  condition,  and (ii)  there  shall be no  Improvement
Allowance with respect to the Expansion Floor, and (iii) the Base Rental payable
for the Expansion Floor shall be determined in accordance with Paragraph  24(b).
Sublandlord shall give Subtenant not less than twelve (12) months written notice
of the date on which  Sublandlord  anticipates  that the Expansion Floor will be
available  for  occupancy by a subtenant  (the  "Anticipated  Occupancy  Date").
Subtenant may then  exercise its right of first  opportunity  by giving  written
notice of the

                                                     PG&E Generating Company and
                                                                  InforMax, Inc.
                                                    Sublease Agreement - Page 15

<PAGE>

exercise to  Sublandlord  within  thirty (30) days after the date of  Landlord's
notice.  A failure by  Subtenant  to respond  within said thirty (30) day period
shall totally extinguish  Subtenant's right of first opportunity to sublease the
Expansion  Floor.  The  right of first  opportunity  granted  hereby  may not be
assigned or transferred by Subtenant.

                  (B) BASE  RENTAL.  If Subtenant  exercises  its right of first
opportunity to sublease the Expansion  Floor,  the Base Rental for the Expansion
Floor shall be computed as an amount equal to the fair market rental rate of the
Expansion  Floor as then  improved,  as if  vacant,  based on its use as general
office  space and taking into  account all  relevant  provisions  of this Lease.
Sublandlord  and Subtenant  shall employ the  procedure and timetable  described
below for the purpose of computing  the fair market rental rate of the Expansion
Floor and the Base Rental properly payable during the first Sublease Year of the
extension term:

                  (i)      Not later than the three hundred fortieth (340th) day
                           prior to the Anticipated Occupancy Date,  Sublandlord
                           shall  deliver to  Subtenant  notice of its  proposed
                           Base Rental for the Expansion Floor.

                  (ii)     Not later than the three hundred thirty-fifth (335th)
                           day  prior  to  the   Anticipated   Occupancy   Date,
                           Subtenant  shall  send to  Sublandlord  notice of its
                           proposed Base Rental for the Expansion Floor.

                  (iii)    In the event  the  parties  negotiate  and agree to a
                           Base  Rental and have  executed  a written  agreement
                           establishing  same on or  before  the  three  hundred
                           twenty-fifth  (325th)  day  prior to the  Anticipated
                           Occupancy  Date,  then  said  Base  Rental  shall  be
                           binding upon the parties.

                  (iv)     In the event the parties have failed to, execute such
                           an  agreement  by said  date,  then  Subtenant  shall
                           engage an appraiser,  who is a member of the American
                           Institute   of  Real   Estate   Appraisers   (a  "MAI
                           Appraiser"),  on or before  the three  hundred  fifth
                           (305th) day prior to the Anticipated  Occupancy Date,
                           and shall  notify  the  Sublandlord  thereof.  In the
                           event  Subtenant  does not engage a MAI  Appraiser as
                           required above, then the Base Rental last proposed by
                           the  Sublandlord  shall be deemed the Base Rental for
                           the Expansion Floor.

                  (v)      Not later than the two hundred  eighty-fifth  (285th)
                           day  prior  to  the   Anticipated   Occupancy   Date,
                           Subtenant  shall deliver to Sublandlord a copy of its
                           appraiser's  determination  of the fair market rental
                           as aforesaid. In the event Subtenant does not deliver
                           a copy  as  aforesaid,  then  the  Base  Rental  last
                           proposed  by  Sublandlord  shall be  deemed  the Base
                           Rental for the Expansion Floor.

                  (vi)     In the event  the  parties  negotiate  and agree to a
                           Base Rental,  and have  executed a written  agreement
                           establishing  same  on  or  before  the  two  hundred
                           seventieth  (370th)  day  prior  to  the  Anticipated
                           Occupancy  Date,  then  said  Base  Rental  shall  be
                           binding upon the parties.

                  (vii)    In the event the parties  have failed to execute such
                           an agreement  by said date,  then  Sublandlord  shall
                           engage a MAI Appraiser,  on or before the two hundred
                           sixty-fifth  (265th)  day  prior  to the  Anticipated
                           Occupancy   Date,  and  shall  notify  the  Subtenant
                           thereof.  In the event  Sublandlord does not engage a
                           MAI appraiser as required above, then the Base Rental
                           proposed by Subtenant's appraiser shall be deemed the
                           Base Rental for the Expansion Floor.

                                                     PG&E Generating Company and
                                                                  InforMax, Inc.
                                                    Sublease Agreement - Page 16

<PAGE>

                  (viii)   No later than the two hundred forty-fifth (245th) day
                           prior to the Anticipated Occupancy Date,  Sublandlord
                           shall deliver to Subtenant a copy of its  appraiser's
                           determination of the fair market rental as aforesaid.
                           In the event  Sublandlord  does not deliver a copy as
                           aforesaid,  then the Base  Rental  last  proposed  by
                           Subtenant's appraiser shall be deemed the Base Rental
                           for the Expansion Floor.

                  (ix)     In the event  the  parties  negotiate  and agree to a
                           Base Rental,  and have  executed a written  agreement
                           establishing  same  on  or  before  the  two  hundred
                           fortieth   (240th)  day  prior  to  the   Anticipated
                           Occupancy  Date,  then  said  Base  Rental  shall  be
                           binding upon the parties.

                  (x)      In the event the parties  have failed to execute such
                           an  agreement  by  said  date,  then  the two (2) MAI
                           Appraisers  shall  choose a third MAI  Appraiser  and
                           notify  Sublandlord and Subtenant of such choice. The
                           parties shall share equally the cost of the three (3)
                           appointed MAI Appraisers.  In the event that said two
                           (2) MAI  Appraisers  cannot  agree on the choice of a
                           third MAI Appraiser and notify the parties thereof by
                           the two hundred thirty-fifth (235th) day prior to the
                           Anticipated Occupancy Date, then the President of the
                           Montgomery  County  Board of Realtors  shall choose a
                           third  MAI  Appraiser  on or before  the two  hundred
                           twenty-fifth  (225th)  day  prior to the  Anticipated
                           Occupancy Date.

                  (xi)     Not later than the two hundred  fifteenth (215th) day
                           prior to the  Anticipated  Occupancy  Date, the third
                           appraiser shall determine the fair market rental rate
                           of the Expansion  Floor,  as then improved,  based on
                           its use as general office space, by selecting as such
                           fair  market  rental  rate either (i) the fair market
                           rental rate proposed by Subtenant's  MAI Appraiser or
                           (ii)  the  fair  market   rental  rate   proposed  by
                           Sublandlord's   MAI  Appraiser  and  submitting  such
                           determination to each party in writing. Based on said
                           third MAI Appraiser's determination,  Sublandlord and
                           Subtenant shall promptly thereafter execute a written
                           agreement  establishing  the  aforesaid  Base Rental,
                           which rent shall be binding upon the parties.

                  (xii)    In no event shall the  newly-established  Base Rental
                           for   the   Expansion   Floor   be  less   than   the
                           per-square-foot  Base Rental  then paid by  Subtenant
                           for the Subleased Premises.

                  The Base Rental for the Expansion  Floor shall be increased at
the same times and by the same  percentage  as the Base Rental for the Subleased
Premises.

         25.  CONSENT OF  LANDLORD.  The  written  consent of  Landlord  to this
Sublease is required  under the terms of the Lease,  and  neither  party  hereto
shall be bound hereby until said consent is fully  executed and delivered  among
the parties.  This Sublease is contingent,  in its entirety,  upon Sublandlord's
obtaining Landlord's consent to this Sublease.  If the aforesaid consent has not
been  obtained  within  thirty  (30) days after  execution  of this  Sublease by
Sublandlord and Subtenant, then either party may terminate this Lease by written
notice to the other given before such consent is obtained.  In the event of such
termination,  Sublandlord  shall return any Security  Deposit and advance rental
payment  theretofore  paid by  Subtenant,  and the parties  shall  thereupon  be
relieved  of any  and  all  liability  hereunder.  Upon  the  execution  hereof,
Sublandlord  will  promptly  submit this  Sublease to Landlord  for its consent.
Sublandlord  shall use reasonable  efforts to obtain such consent within fifteen
(15) days after the execution of this Sublease by both parties.

                                                     PG&E Generating Company and
                                                                  InforMax, Inc.
                                                    Sublease Agreement - Page 17

<PAGE>

         26.   SUBORDINATION  OF  SUBLANDLORD'S  LIEN.   Sublandlord  agrees  to
subordinate  any  lien it may  have on  Subtenant's  property  in the  Subleased
Premises to the lien of any bona fide lender providing financing for Subtenant's
business in the Subleased Premises.

         27. NON-DISTURBANCE AGREEMENT. Sublandlord shall use reasonable efforts
to obtain for Subtenant a  non-disturbance  agreement from  Landlord,  providing
that so long as Subtenant is not in default in the payment of Base Annual Rental
or  Additional  Rental or any  other  material  covenant  or  condition  of this
Sublease,  (i) its  rights  as  Subtenant  hereunder  shall not be  affected  or
terminated,  (ii)  its  possession  of  the  Subleased  Premises  shall  not  be
disturbed,  (iii) no action or proceeding  shall be commenced to remove or evict
Subtenant,  and (iv) this Sublease shall at all times continue in full force and
effect  notwithstanding  the termination of the Lease prior to the expiration or
termination of this Sublease.

         28. QUIET ENJOYMENT. So long as Subtenant shall observe and perform all
of the covenants and agreements binding on it hereunder,  (i) Subtenant shall at
all  times  during  the Term  hereof  peacefully  and  quietly  have  and  enjoy
possession of the Subleased  Premises  without  hindrance by  Sublandlord,  (ii)
Sublandlord  shall not  default  under the Lease,  and (iii)  Sublandlord  shall
maintain the Lease in full force and effect throughout the Term hereof, unless a
termination is caused by factors beyond Sublandlord's control.

         29.     MISCELLANEOUS.

                  (A) NO OFFER.  Submission of this  instrument for  examination
shall not constitute a reservation of or option for the Subleased Premises or in
any manner bind  Sublandlord and no Sublease or obligation on Sublandlord  shall
arise  until  this  instrument  is  signed  and  delivered  by  Sublandlord  and
Subtenant;  provided,  however,  the execution and delivery by Subtenant of this
Sublease to Sublandlord  shall  constitute an irrevocable  offer by Subtenant to
sublease the Subleased  Premises on the terms and conditions  herein  contained,
which offer may not be revoked for thirty (30) days after such delivery.

                  (B) NO PARTNERSHIP.  Nothing  contained in this Sublease shall
be deemed or construed by the parties hereto or by any third party to create the
relationship  of  principal  and  agent,  partnership,  joint  venturer  or  any
association between Sublandlord and Subtenant, it being expressly understood and
agreed  that  neither  the method of  computation  of Base  Rental nor any other
provisions contained in this Sublease nor any act of the parties hereto shall be
deemed to create any relationship  between  Sublandlord and Subtenant other than
the relationship of landlord and tenant.

                  (C)  TIME  OF THE  ESSENCE.  Time  is of the  essence  of this
Sublease and of each and all provisions hereof.

                  (D)  SEPARABILITY.  The legal  invalidity  of any provision of
this  Sublease   shall  not  impair  or  affect  in  any  manner  the  validity,
enforceability or effect of the rests of this Sublease.

                  (E)  COUNTERPARTS.  This  Sublease  may be executed in several
counterparts, all of which shall constitute one and the same document.

                  (F)  MERGER.  All  understandings  and  agreements,   oral  or
written, heretofore made between the parties hereto are merged in this Sublease,
which alone fully and completely expresses the agreement between Sublandlord and
Subtenant.

                                                     PG&E Generating Company and
                                                                  InforMax, Inc.
                                                    Sublease Agreement - Page 18

<PAGE>

         IN WITNESS WHEREOF, the parties hereto have duly executed this Sublease
the day and year first above written.

WITNESS:                              SUBLANDLORD:
                                      PG&E GENERATING COMPANY

/s/ Sherry Blackmon                   By: /s/ P. Chrisman Iribe      (SEAL)
------------------------------           ----------------------------------
                                                  President
                                             -------------------

WITNESS:                              SUBTENANT:
                                      INFORMAX, INC.

/s/ ILLEGIBLE                         By: /s/ Joseph E. Lehnen       (SEAL)
------------------------------           ----------------------------------
                                              8/22/00    CFO
                                             -------------------

                                                     PG&E Generating Company and
                                                                  InforMax, Inc.
                                                    Sublease Agreement - Page 19

<PAGE>

                                   EXHIBIT A

                                     LEASE

                                  [WHEREAS #I]

<PAGE>

                             OFFICE LEASE AGREEMENT

                                     between

                      Bethesda Place II Limited Partnership

                                   (Landlord)

                                       and

                             U.S. Generating Company

                                    (Tenant)

Dated: ________________, 1998

<PAGE>

                                TABLE OF CONTENTS

<TABLE>
<S>                                                                                                            <C>
 1.      BASIC LEASE INFORMATION; DEFINITIONS ...............................................................   1

 2.      LEASE GRANT ........................................................................................   7

 3.      COMMENCEMENT DATE/MEASUREMENT ......................................................................   7

 4.      RENT ...............................................................................................   8

 5.      USE ................................................................................................  14

 6.      STORAGE SPACE ......................................................................................  14

 7.      SERVICES TO BE FURNISHED BY LANDLORD ...............................................................  15

 8.      LEASEHOLD IMPROVEMENTS .............................................................................  16

 9.      GRAPHICS ...........................................................................................  16

10.      REPAIRS AND ALTERATIONS ............................................................................  16

11.      ELECTRICAL SERVICES ................................................................................  17

12.      ENTRY BY LANDLORD ..................................................................................  18

13.      ASSIGNMENT AND SUBLETTING ..........................................................................  18

14.      LIENS ..............................................................................................  19

15.      INDEMNITY ..........................................................................................  19

16.      TENANT'S INSURANCE .................................................................................  20

17.      SUBROGATION ........................................................................................  21

18.      LANDLORD'S INSURANCE ...............................................................................  22

19.      CASUALTY DAMAGE ....................................................................................  23

20.      INTENTIONALLY OMITTED ..............................................................................  24

21.      CONDEMNATION .......................................................................................  24

22.      EVENTS OF DEFAULT ..................................................................................  24

23.      REMEDIES ...........................................................................................  25

24.      LIMITATION OF LIABILITY ............................................................................  26

25.      NO WAIVER ..........................................................................................  27

26.      EVENT OF BANKRUPTCY ................................................................................  27

27.      WAIVER OF JURY TRIAL ...............................................................................  28

28.      CONSTRUCTION OF THE PREMISES .......................................................................  28

<PAGE>

29.      HOLDING OVER .......................................................................................  31

30.      SUBORDINATION TO MORTGAGES .........................................................................  31

31.      ATTORNEYS' FEES ....................................................................................  33

32.      NOTICE .............................................................................................  33

33.      ESTOPPEL CERTIFICATES ..............................................................................  33

34.      ACCESS TO ROOF .....................................................................................  34

35.      EXCEPTED RIGHTS ....................................................................................  35

36.      SURRENDER OF PREMISES ..............................................................................  35

37.      PARKING GARAGE .....................................................................................  35

38.      ACCESS .............................................................................................  36

39.      OPTION TO EXTEND ...................................................................................  37

40.      EXPANSION SPACE ....................................................................................  39

41.      MISCELLANEOUS ......................................................................................  42

42.      RIGHT OF FIRST OFFER ...............................................................................  42

43.      ENTIRE AGREEMENT ...................................................................................  46
</TABLE>

EXHIBITS

         EXHIBIT A        Site Plan of Property [Section 1.B (29)]

         EXHIBIT B        Outline of Premises [Section I.A (6)]

         EXHIBIT C        Rules and Regulations [Article 5]

         EXHIBIT D        Commencement Letter [Section 3.A]

         EXHIBIT E        Outline and Location of Storage Space [Section 6.A]

         EXHIBIT F-1      Building HVAC and Electricity Capacity Specifications
                          [Section 7.A.2]

         EXHIBIT F-2      Janitorial Service Specifications [Section 7.A.4]

         EXHIBIT G        Schedule of Base Building Plans and Specifications
                          [Section 28.A]

         EXHIBIT H

         EXHIBIT I        Title Insurance Policy and Commitment on Property
                          [Section 41.P]

         EXHIBIT J        Construction Schedule [Section 28.C]

         EXHIBIT K        Schedule of Base Rental [Section 4.B]

         EXHIBIT L        Schedule of Insurance Deductibles [Section. 18.B]

         EXHIBIT M        Work Letter [Section 28.A]

<PAGE>

                             OFFICE LEASE AGREEMENT

         This Office Lease  Agreement  (the "Lease") is made and entered into as
of the _____ Day of  ________________,  1998 by and  between  Bethesda  Place II
Limited  Partnership,  a  Maryland  Limited  Partnership  ("Landlord")  and U.S.
Generating Company, a California general partnership ("Tenant").

1.       BASIC LEASE INFORMATION; DEFINITIONS.

         A. The  following are some of the basic lease  information  and defined
terms used in this Lease.

                  (1)  "Additional  Base Rental"  shall mean Excess Basic Costs,
Storage Space Rental,  Parking Garage Rental,  Improvement  Loan Rental (if any)
payable  pursuant to Section 28B, and any other sums  (exclusive of Base Rental)
that are  required  to be paid by Tenant to Landlord  hereunder,  which sums are
deemed to be additional  rent under this Lease.  Additional Base Rental and Base
Rental are sometimes collectively referred to herein as "Rent."

                  (2) "Base Rental" shall mean the minimum base rent that Tenant
is required to pay to Landlord.

                  (3) "Building"  shall mean the office building located at 7600
Wisconsin Avenue Bethesda, Maryland 20814, commonly known as Bethesda Place II.

                  (4) The "Lease Term" shall  consist of a  Preliminary  Term, a
Main Term and, if exercised,  Extension Terms. The "Preliminary Term" shall mean
the period commencing on the Preliminary Commencement Date and ending on the day
before the  Commencement  Date.  Before and during  the  Preliminary  Term,  the
Initial Leasehold  Improvements  will be constructed on a floor-by-floor  basis.
The "Main  Term"  shall mean a period of one  hundred  forty-four  (144)  months
commencing on the Commencement Date.

                           If  Landlord's   Contractor  constructs  the  Initial
Leasehold Improvements:

                           (a) the "Preliminary  Commencement Date" shall be the
earlier of (i) five (5) days after  Landlord  first  obtains a use and occupancy
permit for an entire  floor of the  Premises,  or (ii) the date on which  Tenant
first conducts its business operations on an entire floor of the Premises;

                           (b) the  "Commencement  Date"  shall  be the  date on
which a use and occupancy permit is issued for the Base Building and all Initial
Leasehold Improvements for which the Landlord is responsible; and

                           (c) during the Preliminary  Term, the Lease Term will
commence for each successive individual entire floor of the Premises on the date
on which Tenant first conducts its business operations on such entire floor.

                           If  Tenant's   Contractor   constructs   the  Initial
Leasehold Improvements,

                           (a) the "Preliminary  Commencement Date" shall be the
date on which Tenant first  conducts its business  operations on an entire floor
of the Premises;

<PAGE>

                           (b) the  "Commencement  Date" shall be the earlier of
(i) sixty (60) days after the last floor of the  Premises is delivered to Tenant
with all Base Building items and any Initial  Leasehold  Improvements  for which
Landlord is responsible  substantially  complete with the understanding  that no
more than three (3) floors will be delivered  at any one time and that  delivery
of all such  floors  will occur over a period of no less than  either  eight (8)
weeks (if Tenant's Contractor is the same contractor used by Landlord to perform
the Base  Building  or twelve  (12)  weeks (if  Tenant's  Contractor  is not the
contractor used by Landlord to perform the Base Building), or (ii) the first day
on which Tenant conducts its business operations in the entire Premises; and

                           (c) during the Preliminary  Term, the Lease Term will
commence for each successive individual entire floor of the Premises on the date
on which Tenant first conducts its business operations on such entire floor.

The "Termination Date" shall,  unless sooner terminated as provided herein, mean
the  last  day  of  the  Lease  Term.  Notwithstanding  the  foregoing,  if  the
Termination  Date,  as  determined  herein,  does not occur on the last day of a
calendar month, the Lease Term shall be extended by the number of days necessary
to cause  the  Termination  Date to  occur on the last day of the last  calendar
month of the Lease Term. The  "Extension  Terms",  if exercised,  shall mean the
periods  after the Main Term by which Tenant may extend the Lease Term  pursuant
to Article 39. The term "Lease Year" shall refer to each consecutive twelve (12)
month period  commencing with the Commencement Date (if such date is the 1st day
of a calendar  month) or on the first day of the calendar  month  following  the
month in which such Commencement Date shall occur (if such date is other than on
the 1st day of a  calendar  month)  and  each  successive  anniversary  thereof;
provided,   however  that  the  first  Lease  Year  shall  commence  as  of  the
Commencement Date.

                  (5) "Parking Garage Rental" shall mean the rent that Tenant is
required to pay to Landlord for the Parking Garage.

                  (6) "Premises"  shall mean the area located on the first (1st)
through the eleventh  (11th)  floors of the Building,  containing  approximately
197,017  rentable  square feet of floor space, as outlined on Exhibit B attached
hereto.  The "Rentable Area of the Premises" shall mean the rentable square foot
area determined by measurement of the Premises in accordance with Section 3.B.

                  (7)  "Permitted  Use"  shall mean  general  office use and any
lawful  associated  use for the portions of the  Premises  located on the second
(2nd) through the eleventh (11th) floors of the Building,  and shall mean retail
use and/or general  office use and any lawful  associated use for the portion of
the Premises located on the first (1st) floor of the Building.

                  (8) "Storage  Space Rental" shall mean the rent that Tenant is
required to pay to Landlord for the Storage Space.

                  (9) "Notice Addresses" shall mean the following  addresses for
Tenant and Landlord, respectively:

                           Landlord:

                           c/o Polinger Shannon & Luchs Company
                           5530 Wisconsin Avenue
                           Suite 1000
                           Chevy Chase, Maryland 20815
                           Attention: Mr. Arnold L. Polinger

                                       2
<PAGE>

                    With a copy to:

                    Mr. Gary M. Abramson
                    c/o Tower Construction Company
                    11501 Huff Court
                    North Bethesda, MD 20895

                    and an additional copy to:

                    Richard F. Levin, Esquire
                    Grossberg, Yochelson, Fox & Beyda
                    2100 Pennsylvania Avenue, N.W.
                    Suite 770
                    Washington, D.C. 20037

                    Tenant:

                    Before the Commencement Date:

                    7500 Old Georgetown Road
                    Suite 1300
                    Bethesda, Maryland 20814
                    Attention: P. Chrisman Iribe

                    With a copy to:

                    Stephen A. Herman, Esquire
                    General Counsel
                    U.S. Generating Company
                    7500 Old Georgetown Road
                    Suite 1300
                    Bethesda, Maryland 20814

                    And a copy to:

                    Lawrence A. Shulman, Esquire
                    Shulman, Rogers, Gandal, Pordy & Ecker, P.A.
                    11921 Rockville Pike
                    Third Floor
                    Rockville, Maryland 20852

                    After the Commencement Date:

                    7600 Wisconsin Avenue
                    Bethesda, Maryland 20814
                    Attention: P. Chrisman Iribe

                    With a copy to:

                    Stephen A. Herman, Esquire
                    General Counsel
                    U.S. Generating Company
                    7600 Wisconsin Avenue
                    Bethesda, Maryland 20814

                                       3
<PAGE>

                    And a copy to:

                    Lawrence A. Shulman, Esquire
                    Shulman, Rogers, Gandal, Pordy & Ecker, P.A.
                    11921 Rockville Pike
                    Third Floor
                    Rockville, Maryland 20852

                    Payments of Rent only shall be made payable to the order of:

                    Bethesda Place II Limited  Partnership c/o Polinger Shannon
                    & Luchs Company, Agent or to such other party that Landlord
                    may designate from time to time by written notice to Tenant

         B. The  following  are  additional  definitions  of some of the defined
terms used in the Lease.

                  (1)  "Base  Building"  shall  have the  meaning  set  forth in
Section 28.A.  "Base  Building Plans and  Specifications"  and designated on the
schedule described in Exhibit G attached hereto and made a part hereof.

                  (2)      "Base Year" shall refer to the following:

                           (a)      "Expense  Base Year" shall mean the calendar
                                    year 2001, adjusted,  if the Building is not
                                    at least ninety-five  percent (95%) occupied
                                    for  the  full  calendar  year,  to  reflect
                                    ninety-five  percent (95%) occupancy for the
                                    full calendar year.

                           (b)      "Tax  Base  Year"  shall  mean  the tax year
                                    commencing  July 1,  2001  through  June 30,
                                    2002,  or if later,  the first  twelve  (12)
                                    months  in  which  the   Building  is  fully
                                    assessed as a completed building.

                  (3) "Basic  Costs" shall mean all costs and  expenses  paid or
incurred in connection with operating,  maintaining,  repairing and managing the
Building and the Property, as further described in Section 4.E hereof.

                  (4)  "Broker"  shall means Jones Lang Wootton USA and Polinger
Shannon & Luchs Company.

                  (5)  "Business  Day(s)"  shall mean  Mondays  through  Fridays
exclusive of any business holidays ("Holidays")  designated by Tenant in writing
to Landlord from time to time during the Lease Term.

                  (6)  "Commencement  Date"  shall have the meaning set forth in
Section 1.A(4).

                  (7) "Common  Areas" shall mean the Limited  Common Areas,  the
General Common Areas and the Project Common Areas.

                  (8) "Excess" or "Excess Basic Costs" shall mean the sum of the
Excess Expenses and the Excess Taxes.

                                       4
<PAGE>

                  (9) "Excess  Expenses"  shall mean the amount of the  Expenses
for any for any  calendar  year in excess of the amount of the  Expenses for the
Expense Base Year.

                  (10) "Excess Taxes" shall mean the amount of the Taxes for any
tax  year in  excess  of the  Taxes  for the Tax Base  Year,  as  determined  in
accordance with Section 4.J of this Lease.

                  (11) "Expenses" shall mean Basic Costs exclusive of Taxes.

                  (12)  "Extension  Term"  shall have the  meaning  set forth in
Section 1.A(4).

                  (13) "General  Common Areas" shall mean those outdoor areas on
the  Property  provided for the common use or benefit of Tenant,  Landlord,  the
other  tenants of the  Project,  and  members  of the  general  public,  such as
sidewalks, roadways, plazas, landscaped areas and other similar facilities.

                  (14) "Landlord's Contractor" shall mean the general contractor
designated  by Landlord to bid on the Initial  Leasehold  Improvements,  if such
contractor is engaged by Landlord (as opposed to Tenant) following its selection
by Tenant to perform the Initial Leasehold Improvements. "Landlord's Contractor"
shall also mean the  general  contractor  designated  by Landlord to perform the
Base  Building   construction.   Consequently,   there  may  be  two  Landlord's
Contractors.

                  (15) "Landlord's  Work" shall mean any work to be performed by
Landlord's Contractor pursuant to Article 28.

                  (16) "Laws" shall have the meaning set forth in Article 5.

                  (17) "Lease  Year" shall have the meaning set forth in Section
1.A(4).

                  (18)   "Leasehold   Improvements"   and   "Initial   Leasehold
Improvements" shall have the meanings set forth in Article 8.

                  (19)  "Limited  Common  Areas"  shall mean those  areas in the
Building provided for the common use or benefit of Tenant and Landlord,  such as
corridors,  elevator foyers, restrooms,  lobby areas (whether at ground level or
otherwise), loading docks and other similar facilities.

                  (20) "Main  Term"  shall have the meaning set forth in Section
1.A(4).

                  (21)

                  (22)  "Mortgage"  and  "Mortgagee"  shall have the meaning set
forth in Article 30.

                  (23)  "Normal  Business  Hours"  for the  Building  shall mean
7:00 A.M. to 7:00 P.M. Mondays through Fridays,  exclusive of Holidays,  or such
other hours as may be  designated  by Tenant in writing to Landlord from time to
time during the Lease Term.

                  (24)  "Parking  Garage"  shall have the  meaning  set forth in
Section 37.A.

                                       5
<PAGE>

                  (25)  "Preliminary  Commencement  Date" shall have the meaning
set forth in Section 1.A(4).

                  (26)  "Preliminary  Term"  shall have the meaning set forth in
Section 1.A(4).

                  (27)  "Project"  shall the office and retail  project known as
Bethesda  Place,  which  includes the  Property,  the office  building  known as
Bethesda Place I, with an address of 7700 Wisconsin Avenue, Bethesda,  Maryland,
and the parcel of land on which it is located,  and the apartment building known
as the  Bethesda  Place  Apartments,  with an address of 7701  Woodmont  Avenue,
Bethesda, Maryland, and the parcel of land on which it is located.

                  (28) "Project Common Areas" shall mean those outdoor areas, on
parts of the Project  other than the  Property,  provided  for the common use or
benefit of  Tenant,  Landlord  and the other  tenants  of the  Project,  such as
sidewalks, roadways, plazas, landscaped areas and other similar facilities.

                  (29) "Property" shall mean the Building (including the Parking
Garage) and the parcel of land on which it is located.  The Property is shown on
the site plan attached hereto as Exhibit A.

                  (30) "Required Removables" shall have the meaning set forth in
Section 8

                  (31)  "Storage  Space"  shall  have the  meaning  set forth in
Section 6.A.

                  (32) "Substantial  Completion" of the Landlord's Work shall be
the date  determined  by the  Building  architect  (unless  otherwise  expressly
provided  in this  subsection  32  below)  that  the  Landlord's  Work  has been
performed, other than any details of construction,  mechanical adjustment or any
other matter, the non-completion of which does not materially interfere with the
ability of Tenant's  Contractor to construct the Initial Leasehold  Improvements
(if Tenant's  Contractor  constructs the Initial Leasehold  Improvements) or the
ability of Tenant to commence  beneficial  use and occupancy of the Premises (if
Landlord's Contractor constructs the Initial Leasehold  Improvements;  provided,
however,  that if  Landlord's  Contractor  shall  be  delayed  in  substantially
completing the Landlord's  Work as a result of the occurrence of a Tenant Caused
Delay  (below  defined),  then for purposes of  determining  the date this Lease
commences  with respect to any floor of the  Premises,  the date of  substantial
completion  shall be deemed to be the day that said  Landlord's  Work would have
been   substantially   completed   absent  any  such  Tenant  Caused   Delay(s).
Notwithstanding  the  foregoing,  in the event the Landlord's  Contractor  shall
perform the Initial Leasehold  Improvements,  then Substantial Completion of the
Initial  Leasehold  Improvements  shall be determined  by Tenant's  Architect as
opposed to the Building architect.

                  (33)  "Taxes"  shall  have the  meaning  set forth in  Section
4.E(7).

                  (34) "Tenant  Caused Delay" shall mean any delay  resulting by
reason of any one or more of the following:

                           (a)  Tenant's  failure to furnish  information  or to
respond to any request by Landlord  for any approval or  information  within any
time period prescribed; or

                           (b) Tenant's  insistence  on  materials,  finishes or
installations  that have long lead times  after  having  first been  informed by
Landlord that such materials, finishes or installations will cause a delay; or

                                       6
<PAGE>

                           (c) Changes in any plans and specifications requested
by Tenant after final approval thereof; or

                           (d) Any  request by Tenant  that  Landlord  delay the
completion of any of the Landlord Work; or

                           (e)  Any   breach  or   default   by  Tenant  in  the
performance of Tenant's obligations with respect to construction of the Premises
under this Lease.

                           (f) The delay  resulting  by reason of the failure of
Tenant  to abide the  reasonable  requirements  of  Landlord's  Contractor  with
respect to the  performance  of any  installations  within the Premises by or on
behalf of Tenant by reason of the access rights under Section 28.F(5) below.

                           (g) Any  failure of Tenant or Tenant's  Guarantor  to
timely satisfy the "investment  grade" rating  requirement  described in Section
41.1 of this Lease, if and only if as a consequence  thereof  Landlord elects to
delay the commencement of excavation (as defined in Section 3.D below), or

                           (h) The delay  resulting by reason of the performance
by Landlord of any Base Building  Upgrade (as defined in Section 28.A) requested
by  Tenant  recognizing  that  there  shall be no such  delay in the case of any
particular  Base Building  Upgrade  requested  within the time period  permitted
under the  Construction  Schedule  (as  defined in Section  28.C) to obtain such
particular Base Building Upgrade.

                  (35) "Tenant's  Contractor" shall mean the contractor selected
by Tenant to perform the Initial Leasehold  Improvements,  if such contractor is
engaged by Tenant  following its selection by both Tenant to perform the Initial
Leasehold Improvements.

                  (36) "Tenant's  Property"  shall have the meaning set forth in
Article 8.

                  (37)  "Tenant's  Work" shall mean any work to be  performed by
Tenant or Tenant's Contractor pursuant to Article 28.

                  (38)  "Termination  Date"  shall have the meaning set forth in
Section 1.A(4).

2.       LEASE GRANT.

         Subject  to and upon the terms  herein set  forth,  Landlord  leases to
Tenant and Tenant leases from Landlord the Premises, together with the right, in
common only with  Landlord,  to use the Limited  Common Areas and the right,  in
common with Landlord,  other tenants of the Project,  and members of the general
public, to use the General Common Areas and the Project Common Areas.

3.       COMMENCEMENT DATE/MEASUREMENT.

         A.  The  Lease  Term,   Preliminary   Term,   Main  Term,   Preliminary
Commencement  Date,  Commencement Date and Termination Date are to be determined
in accordance with Section I.A(4).  above.  Promptly after the  determination of
the Commencement  Date,  Landlord and Tenant shall enter into a letter agreement
(the  "Commencement  Letter") on the form  attached  hereto as Exhibit D setting
forth the  Commencement  Date, the Termination Date and any other dates that are
affected by the Commencement Date. Tenant, within seven (7) days

                                       7
<PAGE>

after receipt thereof from Landlord,  shall execute the Commencement  Letter and
return the same to Landlord.

         B. Upon substantial  completion of construction of the Leased Premises,
Landlord's architect shall determine the exact number of rentable square feet in
the Premises in accordance  with the  Washington,  D.C.  Association of Realtors
method  (hereinafter  defined),  and the Base  Rental  shall be  proportionately
adjusted.  The parties agree that the Rentable Area of the Premises,  determined
pursuant to this section, and the adjusted Base Rental shall be set forth in the
Commencement Letter, attached hereto as Exhibit D, to be executed by the parties
within fifteen (15) days after the Commencement  Date of the Lease Term. As used
herein,  the  "Washington,  D.C.  Association of Realtors Method" shall mean the
Washington,  D.C.  Association of Realtors  Standard Method of Measurement dated
January 1989.

         C. Subject to the  provisions  contained  in Section 3.D below,  Tenant
expressly agrees that the adjustment of the Commencement Date and,  accordingly,
the  postponement  of Tenant's  obligation  to pay Rent,  shall be Tenant's sole
remedy and shall  constitute  full  settlement  of all claims that Tenant  might
otherwise  have  against  Landlord  by reason of any  delay by  Landlord  in the
substantial completion of the Landlord's Work.

         D.

4.    RENT.

         A. During each calendar  year, or portion  thereof,  falling within the
Lease Term, Tenant shall pay to Landlord the Base Rental.  The Base Rental shall
be payable in equal monthly installments during the Lease Term, commencing as of
the Preliminary  Commencement  Date. In the event the  Preliminary  Commencement
Date  shall  occur on other  than the first day of a  calendar  month,  the Base
Rental and the Parking  Garage  Rental,  and if  applicable,  the Storage  Space
Rental shall be pro-rated for such month based upon a thirty (30) day month.

         B.

         C.

         D.  Tenant  shall also pay during the Lease Term as Excess  Basic Costs
hereunder the sum of (1) the Excess Taxes for the  applicable  tax year plus (2)
the Excess  Expenses for the applicable  calendar year. The Excess Taxes and the
Excess Expenses shall be computed separate and independent of each other.  Prior
to the first anniversary of the Commencement Date and prior to January 1 of each
subsequent  calendar  year  during  the Lease  Term,  or as soon  thereafter  as
practical,  Landlord shall provide to Tenant the estimated  amount of the Excess
Expenses and the Excess Taxes for the applicable calendar year. On or before the
first day of each month during such calendar year, Tenant shall pay to Landlord,
as Excess Basic Costs, a monthly  installment equal to one-twelfth of Landlord's
estimate.  Landlord  shall  have the right  from time to time,  but no more than
twice, during any such calendar year to revise the reasonable estimate of Excess
Basic Costs to be paid by Tenant for such year and provide Tenant with a revised
statement therefor,  and thereafter the amount Tenant shall pay each month shall
be based upon such revised estimate. If Landlord does not provide Tenant with an
estimate of the Excess  Basic Costs by January 1 of any  calendar  year,  Tenant
shall  continue  to pay a  monthly  installment  based  on the  previous  year's
estimate  until such time as Landlord  provides  Tenant with an estimate of such
Excess Basic Costs for the current  year.  Upon  receipt of such current  year's
estimate, an adjustment shall be made for any month

                                       8
<PAGE>

during the current year with  respect to which Tenant paid monthly  installments
of Excess Basic Costs based on the previous  year's  estimate.  Tenant shall pay
Landlord any underpayment  within thirty (30) days after demand. Any overpayment
shall, at Landlord's  option, be refunded to Tenant within thirty (30) days from
the date  determined by Landlord or credited  against the  installment of Excess
Basic Costs (if any) due for the months immediately  following the furnishing of
such  estimate  provided  that in the  event  Tenant  shall  then be in  default
hereunder in the payment of any monetary sums  (excluding any sums in good faith
disputed by Tenant),  after notice and expiration of the applicable cure period,
Landlord  shall be  entitled to apply any such  overpayment  on account of those
sums then due to  Landlord.  Any amounts  paid by Tenant  based on any  estimate
shall be subject to adjustment  pursuant to the immediately  following paragraph
when actual Basic Costs are determined for such calendar year.  Tenant shall not
be  entitled to any credit or offset if Taxes  decrease  below the Taxes for the
Tax Base Year or Expenses decrease below the Expenses for the Expense Base Year.

         As soon as is practical  following the end of each calendar year during
the Lease Term, Landlord shall furnish to Tenant a detailed statement, certified
by  Landlord  to be  correct  and  including  copies  of any bills  from  taxing
authorities,  of  Landlord's  actual  Basic Costs and the actual  Excess for the
previous  calendar year. If the estimated Excess actually paid by Tenant for the
prior year is in excess of the actual Excess for such prior year,  then Landlord
shall apply such  overpayment  against  Excess  Basic Costs due or to become due
hereunder, provided if the Lease Term expires prior to the determination of such
overpayment, Landlord shall refund such overpayment to Tenant within thirty (30)
days after the date of  Landlord's  statement of the actual Basic Costs for such
year.  Likewise,  Tenant  shall pay to Landlord,  within  thirty (30) days after
demand,  any  underpayment  with  respect to the prior year,  whether or not the
Lease  has  terminated  prior to  receipt  by  Tenant  of a  statement  for such
underpayment,  it being understood that this clause shall survive the expiration
of the Lease.

         E. Basic  Costs shall mean all costs and  expenses  paid or incurred in
each calendar  year in connection  with  operating,  maintaining,  repairing and
managing  the  Building  and the  Property  (exclusive  of the Parking  Garage),
including, but not limited to, the following:

                  (1) Labor costs for all  persons,  not  exceeding  the rank of
Building  manager,  performing  services required or utilized in connection with
the operation,  repair,  replacement and maintenance of and control of access to
the Building and the Property, including but not limited to amounts incurred for
wages, salaries and other compensation for services,  payroll,  social security,
unemployment and other similar taxes, workers' compensation insurance, uniforms,
training,  disability  benefits,  pensions,  hospitalization,  retirement plans,
group insurance or any other similar or like expenses or benefits.

                  (2)  Management  fees which shall not exceed either (i) in the
event  Landlord or an affiliate of Landlord (i.e a management  company owned by,
or under  substantially  common ownership with,  Landlord)  performs same, three
percent (3%) of the Base Rental and Additional Base Rental (exclusive of Parking
Garage Rental) or (ii) in the event an  unaffiliated  third party performs same,
amounts in excess of arms-length competitive prices paid in the Washington, D.C.
metropolitan area for such services. In the event management fees are paid to an
unaffiliated  third  party,  Landlord  shall also be  entitled to include in the
determination  of  Basic  Costs  administrative  charges  for  services  such as
accounting,  secretarial, and bookkeeping incurred with respect to the Building.
Basic  Costs  shall  also  include  accounting   services  and  legal  fees  not
attributable to leasing or collection  activity or negotiations or disputes with
Tenant.

                                       9
<PAGE>

                  (3) Rental and/or purchase costs of materials, supplies, tools
and equipment used in the operation, repair, replacement and maintenance and the
control of access to the Building and the Property.

                  (4)  Amounts   charged  to  Landlord  by  contractors   and/or
suppliers for services, replacement parts, components,  materials, equipment and
supplies  furnished  in  connection  with the  operation,  repair,  maintenance,
replacement  of and  control  of  access  to any  part of the  Building,  or the
Property  generally,  including  the  heating,  air  conditioning,  ventilating,
plumbing, electrical, elevator and other systems and equipment.

                  (5) Premiums and deductibles paid by Landlord for all risks of
physical loss insurance,  earthquake and extended coverage insurance,  liability
and extended  coverage  insurance,  rental loss insurance,  elevator  insurance,
boiler  insurance and other insurance  customarily  carried from time to time by
landlords of comparable office buildings or required to be carried by Landlord's
Mortgagee.

                  (6) Charges for utilities, including but not limited to water,
gas and sewer,  but  excluding  those  electricity  charges  which  Tenant  pays
directly to the utility company or Landlord.

                  (7) "Taxes,"  which for purposes  hereof,  shall mean: (a) all
real estate taxes and  assessments  on the Property,  and taxes and  assessments
levied in substitution or supplementation in whole or in part of such taxes, (b)
all personal property taxes for the Building's personal property,  (c) all other
taxes, fees or assessments now or hereafter levied by any governmental authority
on the  Property,  the  Building  or its  contents or on the  operation  and use
thereof  (except as relate to specific  tenants),  (d) all  amounts  paid to any
business  improvement  district by Landlord,  (e) any solid waste  disposal fees
payable to any  governmental  authority  and (f) all costs and fees  incurred in
connection  with seeking  reductions in or refunds in Taxes  including,  without
limitation, any costs incurred by Landlord to challenge the tax valuation of the
Building or to sustain a proposed  assessment  by reason of a challenge  thereto
from a citizens group or other entity.  Taxes shall exclude income taxes, estate
taxes, inheritance taxes or any other tax computed based upon the net income (as
opposed  to gross  receipts  or gross  income)  of  Landlord,  franchise  taxes,
transfer taxes,  recordation taxes and permit fees. Taxes shall also exclude any
interest  or  penalties  arising by reason of the late  payment of same,  unless
caused by any default by Tenant in the payment of Base Rental or Additional Base
Rental  hereunder.  For  the  purpose  of  determining  real  estate  taxes  and
assessments  for any given tax year, the amount to be included in Taxes for such
year shall be as follows:  (1) with  respect to any special  assessment  that is
payable in  installments,  Taxes for such year shall  include  the amount of the
installment  (and any interest) due and payable  during such year;  and (2) with
respect to all other real estate  taxes,  Taxes for such year shall  include the
amount due and payable for such year.  If a reduction  in Taxes is obtained  for
any year of the Lease Term during which Tenant paid Excess Taxes, then Taxes for
such year will be retroactively  adjusted and Landlord shall provide Tenant with
a credit or refund based on such  adjustment,  after deduction  therefrom of any
expenses  incurred  in  obtaining  such  refund.  Likewise,  if a  reduction  is
subsequently  obtained  for Taxes for the Tax Base Year,  Taxes for the Tax Base
Year  shall  be  restated  and  the  Excess  Taxes  for  all  subsequent   years
re-computed. Tenant shall pay to Landlord any such increase in the Excess within
thirty (30) days after Tenant's receipt of a statement therefor from Landlord.

                  (8) Landscape  expenses and costs of  maintaining,  repairing,
resurfacing and striping of the roadways of the Property,  if any, and the costs
of maintaining and repairing the other General Common Areas.

                                       10
<PAGE>

                  (9)  Cost of all  maintenance  service  agreements,  including
those for equipment,  alarm service, trash removal, window cleaning,  drapery or
venetian blind  cleaning,  janitorial  services,  pest control,  uniform supply,
plant maintenance and landscaping.

                  (10)  Cost of all  other  repairs,  replacements  and  general
maintenance of the Property and Building  neither  specified  above nor directly
billed to Tenant.

                  (11) The amortized  cost of capital  improvements  made to the
Building or the Property  which are: (a)  primarily  for the purpose of reducing
operating  expense  costs;  or (b)  required to comply  with any laws,  rules or
regulations of any  governmental  authority first  applicable to the Property or
Building  subsequent  to the  Preliminary  Commencement  Date.  The cost of such
capital  improvements  (herein  referred to collectively  as "Permitted  Capital
Expenditures") shall be amortized over the estimated useful life of such capital
improvement and shall, at Landlord's option,  include interest at a rate that is
reasonably  equivalent to the interest  rate that Landlord  would be required to
pay to finance  the cost of the capital  improvement  in question as of the date
such capital improvement is performed,  not to exceed the rate then announced by
Bank America, N.A., or its successor, as its publicly announce "prime rate".

                  (12) Cost to furnish or maintain lobby  attendants or security
services or personnel for the Building.

                  (13) Any other  expense  or charge  of any  nature  whatsoever
which,  in  accordance  with  general  industry  practice  with  respect  to the
operation of a first-class  office building,  would be construed as an operating
expense typically passed through to tenants.

         Notwithstanding  the  foregoing,  Basic  Costs shall not  include:  any
expenses of a capital nature, including without limitation capital improvements,
capital  repairs,  capital  equipment  and capital  tools,  all as determined in
accordance with generally accepted accounting principles,  consistently applied,
except the Permitted  Capital  Expenditures;  any costs of constructing the Base
Building or the Leasehold  Improvements;  depreciation or  amortization,  except
amortization of the Permitted Capital Expenditures; lease commissions;  interest
or  principal  payments on  mortgages  or other  debts of  Landlord  (except the
interest  permitted  in  Section  4.E(11)  with  respect  to  Permitted  Capital
Expenditures);  amounts paid to any person,  firm or  corporation  related to or
otherwise  affiliated  with  Landlord or its  management  company or any general
partner or member of Landlord,  which are in excess of  arms-length  competitive
prices paid in the Washington,  D.C. metropolitan area for the services or goods
provided;  ground rent payments to any ground lessor; and the costs of any items
for which  Landlord (a) is reimbursed by insurance or  condemnation  proceeds or
parties  other  than  Tenant  pursuant  this  Article  4, or (b) would have been
covered by insurance proceeds had Landlord  maintained the insurance required to
be  maintained  by Landlord  under this Lease;  the cost of any repairs or other
work, to the extent covered by any warranty;  any 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 (a) the  violation or breach by Landlord of the terms and  conditions  of
the Lease,  or (b) any act of negligence or willful  misconduct by Landlord,  or
Landlord's  agents,  employees  and  assigns;  Landlord's  general  overhead and
general administrative expenses, except for the costs of accounting and computer
services relating to the operation of the Building and/or any on-site management
office located at the Building;  rentals and other related expenses  incurred in
leasing  air  conditioning  systems,  elevators  or other  equipment  ordinarily
considered  to be  capital  in  nature  except  (a)  equipment  which is used in
providing  janitorial or similar services which are provided to Tenant and which
is not affixed to the  Building,  (b) equipment the purchase of which would be a
Permitted Capital Expenditure,  and (c) maintenance costs (including maintenance
contract charges) for any

                                       11
<PAGE>

capital equipment in the Building;  costs of correcting defects in the design or
construction  of the Base Building or the materials used in the  construction of
the Base  Building  (except  to the  extent  Tenant  specified  such  design  or
materials or such costs are Permitted Capital Expenditures);  costs and expenses
associated  with the  operation  of the  business of the person or entity  which
constitutes  Landlord,  such as Landlord's general partnership  overhead, as the
same are  distinguished  from the costs of operation of the Building,  including
accounting  and legal  matters  and costs of  selling  or  financing  Landlord's
interest  in the  Property;  any  costs,  fines  or  penalties  incurred  due to
violations by Landlord of any federal, state or local law, statute or ordinance,
or any  rule,  regulation,  judgment  or decree  of any  governmental  authority
(recognizing  that Landlord  shall be entitled to be fully  reimbursed by Tenant
for all such costs,  fines or penalties  under  Section 5 below in the event any
such  costs,  fines or  penalties  resulted  by reason of any act or omission of
Tenant  or by  any  party  claiming  by,  through,  or  under  Tenant);  or  any
advertising  or  promotional  expenses for the Building  (other than expenses to
hire  prospective  building  personnel).  Any Basic  Costs  (other than costs of
maintaining  and repairing the General  Common Areas) which benefit the Property
and other  properties in the Project shall be equitably  allocated  among all of
the benefitted properties.  Tenant shall be entitled at its request to designate
the supplier of those utilities,  if any, which are available from more than one
supplier,  recognizing,  however,  that in the event  utilities  from a supplier
designated  by Tenant shall be  thereafter  suspended or  interrupted,  and such
suspension or interruption  would not have occurred had the Landlord  Designated
Supplier (defined below) provided such utilities hereunder, then notwithstanding
any provision  contained in Section 7.B below, no rent shall abate. The Landlord
Designated  Supplier  shall be  deemed  to be the  supplier  previously  used by
Landlord  hereunder,  if any,  or the  supplier  designated  by  Landlord as its
preferred supplier by written notice no less than thirty (30) days preceding the
date of the interruption or suspension..

         F.  Tenant,  within one  hundred  eighty  (180)  days  after  receiving
Landlord's statement of actual Basic Costs for a particular calendar year, shall
have the right to provide  Landlord with written notice (the "Review Notice") of
its intent to review  Landlord's  books and records  relating to the Basic Costs
for such  calendar  year.  Within a  reasonable  time after  receipt of a timely
Review Notice, Landlord shall make such books and records available to Tenant or
Tenant's  agent  for  its  review  at  either  Landlord's  main  office  in  the
Washington,  D.C. area or at the office of the Building, provided that if Tenant
retains an agent to review  Landlord's  books and records for any calendar year,
such agent must execute a copy of a  confidentiality  agreement  with respect to
such audit and not be compensated on a contingency basis].  Except to the extent
expressly provided below in this Section 4.F, Tenant shall be solely responsible
for any and all costs, expenses and fees incurred by Tenant or Tenant's agent in
connection  with such review.  If Tenant elects to review  Landlord's  books and
records,  within sixty (60) days after such books and records are made available
to Tenant,  Tenant shall have the right to give Landlord  written notice stating
in reasonable detail any objection to Landlord's statement of actual Basic Costs
for such  calendar  year.  If Tenant fails to give  Landlord  written  notice of
objection  within such sixty (60) day period or fails to provide Landlord with a
Review Notice  within the one hundred  eighty (180) day period  provided  above,
Tenant shall be deemed to have approved  Landlord's  statement of Basic Costs in
all respects and shall thereafter be barred from raising any claims with respect
thereto.  Upon  Landlord's  receipt of a timely  objection  notice from  Tenant,
Landlord and Tenant shall work together in good faith to resolve the discrepancy
between  Landlord's  statement  and  Tenant's  review.  If  Landlord  and Tenant
determine  that Basic  Costs for the  calendar  year in  question  are less than
reported,  Landlord shall provide Tenant with a credit against future Additional
Base Rental in the amount of any  overpayment  by Tenant,  or shall  refund such
amount to Tenant if the Lease  Term has  terminated  or  expired.  Likewise,  if
Landlord and Tenant determine that Basic Costs for the calendar year in question
are greater than reported,  Tenant shall forthwith pay to Landlord the amount of
underpayment by Tenant. Tenant shall bear all costs of any such inspection of

                                       12
<PAGE>

Landlord's  books and records;  provided,  however,  that if any such inspection
shows that the amount  reported by  Landlord  to Tenant as Expenses  exceeded by
more than three  percent  (3%) the  actual  amount of the  Expenses  or that the
amount  reported  by  Landlord  to Tenant as Taxes  exceeded  by more than three
percent (3%) the actual amount of the Taxes,  then Landlord  shall pay to Tenant
the reasonable cost of Tenant's  inspection.  Any information obtained by Tenant
pursuant to the  provisions  of this section  shall be treated as  confidential.
Notwithstanding  anything herein to the contrary,  Tenant shall not be permitted
to examine  Landlord's  books and records or to dispute any  statement  of Basic
Costs unless  Tenant has paid to Landlord the amount due as shown on  Landlord's
statement  of actual Basic Costs,  said payment  being a condition  precedent to
Tenant's right to examine Landlord's books and records.

         G.  Tenant  covenants  and agrees to pay to  Landlord  during the Lease
Term,  without any setoff or deduction  whatsoever,  the full amount of all Base
Rental and Additional Base Rental due hereunder.  In addition,  Tenant shall pay
and be liable for, as additional rent, all rental,  sales and use taxes or other
similar taxes (exclusive of income taxes, estate taxes, inheritance taxes or any
other tax based on the net income, as opposed to gross receipts or gross income,
of Landlord,  and exclusive of any taxes  included in the definition of Taxes in
Section 4.E(7)),  if any, levied or imposed by any city, state,  county or other
governmental  body  having  authority  with  respect  to such  Base  Rental  and
Additional  Base Rental,  such payments to be in addition to all other  payments
required to be paid to Landlord by Tenant under the terms and conditions of this
Lease.  Any such payments  shall be paid  concurrently  with the payments of the
Rent on which the tax is based. The Base Rental, Tenant's Excess Basic Costs and
any recurring  monthly  charges due hereunder  (such as Parking  Garage  Rental,
Storage  Space Rental and, if any,  Improvement  Loan  Rental)  shall be due and
payable in advance on the first day of each calendar month during the Lease Term
without demand,  provided that the installment of Base Rental for the first full
calendar  month of the Lease Term shall be payable  upon the  execution  of this
Lease by Tenant.  All other  items of Rent shall be due and payable by Tenant on
or before ten (10) days after billing by Landlord.  If the Lease Term  commences
on a day other than the first day of a  calendar  month or  terminates  on a day
other than the last day of a calendar  month,  then the monthly  Base Rental and
Tenant's  Excess  Basic Costs for such month shall be prorated for the number of
days in such month  occurring  within the Lease  Term based on a  fraction,  the
numerator of which is the number of days of the Lease Term that fell within such
calendar  month and the  denominator  of which is thirty (30). All such payments
shall be by a good and  sufficient  check or by wire  transfer.  No  payment  by
Tenant or receipt or  acceptance by Landlord of a lesser amount than the correct
amount of Rent due under this  Lease  shall be deemed to be other than a payment
on account of the earliest  Rent due  hereunder,  nor shall any  endorsement  or
statement on any check or any letter accompanying any check or payment be deemed
an accord  and  satisfaction,  and  Landlord  may  accept  such check or payment
without prejudice to Landlord's right to recover the balance or pursue any other
available remedy. The acceptance by Landlord of any Rent on a date after the due
date of such payment shall not be construed to be a waiver of  Landlord's  right
to declare a default for any other late payment.  Tenant's  covenant to pay Rent
shall be independent of every other covenant set forth in this Lease.

         H.

         I.

         J.

         K.

                                       13
<PAGE>

5.       USE.

         The  Premises  shall  be used  for the  Permitted  Use and for no other
purpose.  Tenant  agrees  not to use or permit the use of the  Premises  for any
purpose  which is illegal,  dangerous  to life,  limb or  property or which,  in
Landlord's  reasonable  opinion,  creates a nuisance or which would increase the
cost of insurance  coverage with respect to the  Building.  Tenant shall conduct
its  business  and  control  its  agents,  servants,   contractors,   employees,
customers,  licensees,  and  invitees  in such a manner  as not to  unreasonably
interfere  with,  annoy or disturb  tenants of the other office  building or the
apartment  building in the Project,  or unreasonably  interfere with Landlord in
the management and operation of the Building.  Tenant will maintain the Premises
in a clean and  healthful  condition,  and  comply  with all  laws,  ordinances,
orders,  rules and regulations of any  governmental  entity,  including  without
limitation,  the Americans with  Disabilities Act  (collectively  referred to as
"Laws")  with  reference to the  operation of Tenant's  business and to the use,
condition,  configuration or occupancy of the Premises.  Landlord, at Landlord's
expense  (subject  to  reimbursement  by Tenant  pursuant  to Article 4, if such
expense is included in the definition of "Basic  Costs"),  shall comply with all
Laws relating to the roof and structural elements of the Building and the Common
Areas. Each party, within ten (10) days after receipt thereof, shall provide the
other party with copies of any notices it receives  with  respect to a violation
or  alleged  violation  of any  Laws.  Tenant  will  comply  with the  rules and
regulations  of the  Building  attached  hereto  as  Exhibit  C and  such  other
reasonable  rules and  regulations  adopted and altered by Landlord from time to
time  and  will  cause  all of its  agents,  servants,  contractors,  employees,
customers, licensees and invitees to do so.

6.       STORAGE SPACE.

         A. The  "Storage  Space" is the space in the P-5 Level of the  Building
shown on the attached  Exhibit E. Throughout the Lease Term,  Tenant shall lease
the Storage  Space,  and Tenant shall pay Landlord,  as Additional  Base Rental,
Storage  Space  Rental  for the  Storage  Space  so  leased,  in  equal  monthly
installments.

         B. The  Storage  Space  leased  by  Tenant  shall be used  only for the
storage of Tenant's Property.  Landlord, at Tenant's expense,  shall provide the
following finishes to the Storage Space leased by Tenant:  fire-rated  drywalls,
solid-core wood doors with deadbolt locks, fire and life safety systems,  to the
extent  required  by  code,  and  ceiling   lighting.   Landlord  shall  provide
electricity for lighting purposes and no other services to the Storage Space.

         C. In the event that the Storage  Space  leased by Tenant is damaged or
destroyed  by fire or other  casualty,  Tenant may  terminate  its lease of such
Storage Space by written notice to Landlord  within ten (10) days after the date
of such  casualty.  If Tenant does not so  terminate  its lease of such  Storage
Space, then Landlord, at Landlord's expense, shall promptly restore such Storage
Space to the  condition  described in Section 6.B, and the Storage  Space Rental
shall  be  abated  from the  date of the  casualty  until  such  restoration  is
substantially completed.

         D.  On the  Termination  Date,  Tenant  shall  remove  all of  Tenant's
Property  from the Storage  Space and surrender the Storage Space to Landlord in
broom clean, "as is" condition.

7.       SERVICES TO BE FURNISHED BY LANDLORD.

         A.  Landlord,  as part of Basic Costs  (except as otherwise  provided),
agrees to furnish  Tenant  within the Premises and the Limited  Common Areas the
following services:

                                       14
<PAGE>

                  (1) Hot  and  cold  water  for  use in the  lavatories  in the
Limited Common Areas and in any private lavatories and kitchens in the Premises,
and at all other  valved  outlets  at the  locations  in the  Premises  shown on
Tenant's Space Plan.

                  (2) Central heat and air conditioning in season, in accordance
with the Building Standard HVAC specifications set forth on the attached Exhibit
F-l,  during Normal  Business  Hours and such other hours as may be requested by
Tenant by written or  telephonic  notice  delivered to Landlord at the office of
the Building, during Normal Business Hours, at least two (2) hours in advance of
the beginning of the period of time for which such usage is requested.

                  (3)  Maintenance  and repair of all Common Areas in the manner
and to the  extent  standard  for first  class  office  buildings  in  Bethesda,
Maryland.

                  (4) Janitor service in accordance with the  specifications set
forth on the attached Exhibit F-2 after 6:00 p.m. on Business Days.

                  (5)  Automatically  operated  elevator service 24 hours a day,
seven days a week.

                  (6) Electricity for lighting  purposes and operation of all of
Tenant's equipment, subject to the requirements of Section 11.B below.

                  (7) Adequate  supplies for all of the toilet rooms  located in
the Limited Common Areas.

                  (8) All electric  bulbs and  fluorescent  tubes in permanently
installed light fixtures in the Premises.

                  (9) A  reasonable  number of keys to the suite  entry doors to
each portion of the Premises located on a separate floor of the Building; and

                  (10)  An  electronic  card  security  access  system  for  the
Building and the Parking Garage and a reasonable  number of access cards for use
by Tenant's employees and subtenants.

         B.  The  failure  by  Landlord  to  any  extent  to  furnish,   or  the
interruption or termination of, any services in whole or in part, resulting from
adherence to laws,  regulations and administrative  orders,  wear, use, repairs,
improvements,  alterations  or any  causes  beyond  the  reasonable  control  of
Landlord shall not render  Landlord  liable in any respect nor be construed as a
constructive  eviction of Tenant,  nor give rise to an  abatement  of Rent,  nor
relieve Tenant from the obligation to fulfill any covenant or agreement  hereof,
except as  follows.  In the event  that (i)  electricity  and/or  heating or air
conditioning  (in season) of the Premises,  or elevator service in the Building,
shall not be  furnished  by reason of matters  either (x) within the  control of
Landlord for more than three (3)  consecutive  business  days, or (y) beyond the
control of Landlord for more than five (5)  consecutive  business days, and (ii)
Tenant, in its reasonable business judgment, determines that it is unable to use
and occupy the Premises (or any part thereof) as a result thereof, then the Base
Rental  Tenant is  obligated to pay  hereunder  shall abate with respect to that
part of the  Premises  which Tenant does not use and occupy,  commencing  on the
fourth or sixth such day until the date on which such services and utilities are
restored, unless the failure to furnish such services and utilities is caused by
Tenant's  acts or  omissions or as  otherwise  provided in the last  sentence of
Section 4.E above. Landlord will use reasonable efforts to diligently remedy any
interruption  in the  furnishing  of any  services or  utilities  required to be
performed by Landlord hereunder. Should any of the equipment or

                                       15
<PAGE>

machinery  used in the  provision of such  services or  utilities  for any cause
cease to function  properly,  Landlord shall use reasonable  diligence to repair
such  equipment  or  machinery.  Landlord  shall use  reasonable  efforts not to
interrupt or reduce utility  services  during Normal Business Hours for purposes
of making  discretionary  alterations,  improvements  or repairs,  and shall, if
feasible,  give Tenant at least  twenty-four (24) hours telephonic notice of any
such interruption of utility service.

         C. Tenant expressly  acknowledges that if Landlord,  from time to time,
provides  one or more  lobby  attendants  (which  Landlord  will not do  without
Tenant's sole discretionary  approval, and will do upon Tenant's written request
provided  Tenant bears all costs thereof as Additional  Base Rental) or security
services,  Landlord  shall not be deemed to have warranted the efficiency of any
lobby  attendant,  security  personnel,  service,  procedures  or equipment  and
Landlord  shall not be liable in any manner for the failure of any such security
personnel, services, procedures or equipment to prevent or control, or apprehend
anyone suspected of personal injury, property damage or any criminal conduct in,
on  or  around  the  Property,  unless  such  failure  results  from  Landlord's
negligence or willful misconduct.

8.       LEASEHOLD IMPROVEMENTS.

         Any trade fixtures,  unattached and movable equipment or furniture,  or
other  personalty  brought into the  Premises,  the Storage Space or the Parking
Garage  by Tenant  ("Tenant's  Property")  shall be owned or  leased by  Tenant.
Tenant shall remove all such  Tenant's  Property from the Premises in accordance
with the terms of Article  36 hereof.  Any and all  alterations,  additions  and
improvements to the Premises,  including any built-in  furniture  (collectively,
"Leasehold  Improvements")  shall be owned by Landlord and shall remain upon the
Premises,  all without  compensation,  allowance or credit to Tenant;  provided,
however,  that following the Commencement  Date, in the event Tenant requests to
perform any Leasehold  Improvements  [i.e.  improvements other than the "Initial
Leasehold  Improvements"  (defined  below)],  and  Landlord's  consent  to  such
Leasehold  Improvements  shall be required  under this Lease,  Landlord shall be
entitled at the time of its consent  thereto to condition  such consent upon the
requirement  that  Tenant  remove  the  proposed  Leasehold   Improvements  upon
expiration  of the  Term at the  sole  cost  and  expense  of  Tenant.  Any such
designated  Leasehold  Improvements,  together  with any  installations  made by
Tenant upon the roof,  or any work of visual art  subject to the Visual  Artists
Right Act of 1990 (17 U.S.C.  Section 101 et.  seq.)  (commonly  referred to as"
VARA")  installed  on or about  the  Premises  by Tenant  shall be  collectively
referred to herein as the "Required Removables".  Nothing contained herein shall
be deemed to constitute the  designation by Landlord of Tenant as its agent with
respect to any works of visual art  proposed to be  installed by or on behalf of
Tenant in the Building.  Tenant expressly covenants to obtain the written waiver
of any artist of any work of visual art to the removal of same from the Building
upon termination or expiration of this Lease.  The Leasehold  Improvements to be
constructed by Landlord or Tenant prior to the Commencement  Date, in accordance
with Article 28 are sometimes  hereinafter referred to as the "Initial Leasehold
Improvements".

9.       GRAPHICS.

         A.

         B.

         C.  Landlord  shall not install,  or permit any other party to install,
any signage on the  exterior of the Building or the  Property  without  Tenant's
prior written  approval,  which  approval may be granted or withheld in Tenant's
sole discretion.

                                       16
<PAGE>

 10.     REPAIRS AND ALTERATIONS.

         A. Except to the extent such  obligations  are  imposed  upon  Landlord
hereunder,  Tenant, at its sole cost and expense,  shall perform all maintenance
and repairs to the Premises as are necessary to keep the same in good  condition
and  repair  throughout  the entire  Lease  Term,  reasonable  wear and tear and
casualty  damage not  required  to be  repaired  by Tenant  hereunder  excepted.
Tenant's repair and maintenance  obligations  with respect to the Premises shall
include,  without  limitation,  any  necessary  repairs with respect to: (1) any
carpet or other floor covering, (2) any interior partitions,  (3) any doors, (4)
the interior side of any demising walls,  (5) any telephone and computer cabling
that  serves  Tenant's  equipment  exclusively,  and  (6) any  supplemental  air
conditioning  units,  private  showers and  kitchens,  including any plumbing in
connection  therewith,  and similar facilities serving Tenant  exclusively.  All
such work shall be performed in  accordance  with Section 10.C below.  If Tenant
fails to make any  necessary  repairs  to the  Premises,  Landlord  may,  at its
option,  after fifteen (15) days written notice to Tenant (or such longer period
as may be reasonably  required to complete  such  repairs,  provided that Tenant
commences the same promptly  after receipt of Landlord's  notice and  thereafter
diligently proceeds with the same), make such repairs,  and in such event Tenant
shall pay the cost  thereof  to the  Landlord  together  with an  administrative
charge thereon of five percent (5%) of such costs,  on demand as Additional Base
Rental.  Tenant, at its option, may at any time or from time to time, by written
notice  to  Landlord,  elect  to have  Landlord  assume  responsibility  for the
performance of any or all of Tenant's  maintenance and repair  obligations under
this  Section  10.A.  In such  event,  Tenant  shall pay to  Landlord  the costs
incurred by Landlord to perform such maintenance and repairs, as Additional Base
Rent. Any such repair or  maintenance  costs shall be paid on a monthly or other
periodic  basis,  as mutually  agreed upon by Landlord and Tenant at the time of
Tenant's request to Landlord for performance by Landlord of such services.

         B. Landlord  shall,  at its expense  (except as included in Basic Costs
pursuant to Article 4), keep and maintain in good repair and working order,  and
make all repairs to and perform  necessary  maintenance upon: (a) all structural
elements  of the  Building;  and (b) all  mechanical,  electrical  and  plumbing
systems  that serve the  Building;  (c) the toilet  rooms,  lobbies,  elevators,
corridors, stairways and other Limited Common Areas in the Building; and (d) the
exterior of the  Building,  including the roof and windows.  Landlord  shall use
reasonable efforts to minimize  disruption to Tenant's business  operations when
making  repairs to the Premises,  including,  when  requested by Tenant,  making
non-emergency  repairs outside of Tenant's normal  operating  hours. If Landlord
refuses or neglects to promptly  commence and complete repairs or maintenance to
the Property  necessary to satisfy the  provisions of this section,  Tenant may,
after fifteen  (15)days written notice to Landlord (or such longer period as may
be  reasonably  required  to  complete  such  repairs,  provided  that  Landlord
commences the same  promptly  after  receipt of Tenant's  notice and  thereafter
diligently  proceeds  with the same),  but shall not be  required  to,  make and
complete such repairs or  maintenance,  in which event Landlord shall pay Tenant
the cost of such repairs or maintenance upon demand.

         C. Tenant shall not make or allow to be made any alterations, additions
or  improvements  to the Premises  which (i) affect the  structural  elements or
exterior of the Building,  (ii) include or require material modifications to the
mechanical,  electrical,  plumbing or life safety  systems of the  Building,  or
(iii)  cost  more  than  Fifty  Thousand  Dollars  ($50,000.00),  without  first
obtaining the written  consent of Landlord in each such instance,  which consent
shall not be  unreasonably  withheld for  nonstructural,  interior  alterations.
Prior  to  commencing  any  such  work  requiring  Landlord's  consent  and as a
condition to obtaining such consent, Tenant must furnish Landlord with plans and
specifications  reasonably  acceptable  to  Landlord;  names  and  addresses  of
contractors; copies of necessary permits and

                                       17
<PAGE>

approvals;  and  evidence  of  contractor's  and  subcontractor's  insurance  in
accordance with Section 16.B hereof. All improvements,  alterations or additions
(whether or not requiring  Landlord's consent hereunder) shall be constructed in
a good and workmanlike manner new materials of good quality.  Upon completion of
any  improvements,  alterations  or additions,  Tenant shall furnish  "as-built"
plans and full and final waivers of liens.  All  improvements,  alterations  and
additions shall comply with all insurance requirements,  codes, ordinances, laws
and regulations,  including without limitation,  the Americans with Disabilities
Act. If Landlord so requests,  Landlord,  at its  expense,  shall be entitled to
oversee the  construction of any  alterations,  additions or  improvements  that
affect  the   structure  of  the   Building  or  include  or  require   material
modifications  to any of the  mechanical,  electrical,  plumbing  or life safety
systems  of  the   Building.   Landlord's   approval  of   Tenant's   plans  and
specifications  for any work  performed  for or on behalf of Tenant Shall not be
deemed to be a  representation  by Landlord  that such plans and  specifications
comply with applicable insurance requirements,  building codes, ordinances, laws
or regulations or that the alterations,  additions and improvements  constructed
in accordance with such plans and  specifications  will be adequate for Tenant's
use.

11.      ELECTRICAL SERVICES.

         A.  During the  Preliminary  Term,  Tenant  shall pay to  Landlord,  as
Additional Base Rental,  a fraction of the cost of all  electricity  consumed or
utilized  upon the Property,  the  numerator of which  fraction is the number of
floors of the  Premises  for which the Lease  Term has then  commenced,  and the
denominator  of which  fraction  is eleven  (11).  The  Additional  Base  Rental
described in this Section 11.A shall be paid by Landlord to Tenant within thirty
(30) days after  Tenant's  receipt of an invoice from Landlord  therefor,  which
invoice  shall be  accompanied  by a copy of the bill from the  public  electric
utility company.

         B. Commencing on the  Commencement  Date and thereafter  throughout the
remaining  Lease  Term,  Tenant  shall be  responsible  for the  payment for all
electricity consumed or utilized upon the Property. Tenant shall pay directly to
the public electric  utility  company,  or other electric  supplier  selected by
Tenant,  in its sole  discretion,  all charges for  electricity  supplied to the
Property.  Tenant's use of electrical  service in the Premises shall not exceed,
either in voltage,  rated capacity, use or overall load, that which the Building
electrical  equipment  is designed to handle.  In the event Tenant shall wish to
consume electrical service in excess of the capacity of the Building  electrical
equipment,  as  described  more  fully in the  specifications  set  forth on the
attached Exhibit F-l, the installation of any necessary utility service upgrades
shall be paid for by Tenant.

12.      ENTRY BY LANDLORD.

         Landlord  and its  agents or  representatives  shall  have the right to
enter the  Premises  at  reasonable  times to inspect  the same,  or to show the
Premises to prospective purchasers,  mortgagees, tenants (during the last twelve
months of the Lease Term) or insurers, or to clean or make repairs,  alterations
or additions  thereto,  including any work that Landlord deems necessary for the
safety,  protection or preservation of the Building or the occupants thereof, or
to facilitate repairs,  alterations or additions to the Building. Except for any
entry by Landlord in an emergency  situation or to provide  normal  cleaning and
janitorial  service,  Landlord shall provide Tenant with reasonable prior notice
of any  entry  into  the  Premises,  which  notice  may be  given  verbally.  If
reasonably  necessary for the protection and safety of Tenant and its employees,
Landlord shall have the right to temporarily  close the portions of the Premises
to perform  repairs,  alterations  or additions in the  Premises,  provided that
Landlord shall use  reasonable  efforts to perform all such work on weekends and
after Normal Business Hours.  Entry by Landlord hereunder shall not constitute a
constructive eviction or entitle Tenant to any abatement or reduction of Rent by
reason thereof.

                                       18
<PAGE>

13.      ASSIGNMENT AND SUBLETTLNG.

         A. Except as  otherwise  set forth in Section  13.C,  Tenant  shall not
assign,  sublease,  transfer or encumber  this Lease or any interest  therein or
grant any license, concession or other right of occupancy of the Premises or any
portion  thereof or  otherwise  permit the use of the  Premises  or any  portion
thereof  by any party  other than  Tenant  (any of which  events is  hereinafter
called a  "Transfer")  without  the prior  written  consent of  Landlord,  which
consent shall not be unreasonably withheld,  conditioned or delayed with respect
to any  proposed  assignment  or  subletting.  Landlord's  consent  shall not be
considered  unreasonably  withheld if the  proposed  use is  different  than the
Permitted Use or Tenant is in default.  Any  attempted  Transfer in violation of
the terms of this Article  shall,  at  Landlord's  option,  be void.  Consent by
Landlord to one or more  Transfers  shall not operate as a waiver of  Landlord's
rights as to any subsequent Transfers.

         B.  If  Tenant  requests  Landlord's  consent  to a  Transfer,  Tenant,
together with such request for consent,  shall provide Landlord with the name of
the  proposed  transferee  and  the  nature  of the  business  of  the  proposed
transferee,  the  term,  use,  rental  rate and all  other  material  terms  and
conditions of the proposed Transfer,  including,  without limitation,  a copy of
the proposed assignment, sublease or other contractual documents. Landlord shall
consent to or reasonably  refuse to consent to such  Transfer in writing  within
fifteen  (15) days after  receipt of all of the  information  and  documentation
required  herein.  In the event  Landlord  consents  to any such  Transfer,  the
Transfer and consent  thereto  shall be in a form  approved by  Landlord,  which
approval shall not be unreasonably withheld, conditioned or delayed.

         C.  Tenant  shall have the right to assign  this Lease or sublet all or
any part of the Premises to an entity which  controls,  is  controlled  by or is
under common control with Tenant,  without the necessity of obtaining Landlord's
consent but with no less than thirty (30) days prior written  notice to Landlord
thereof.

         D. Any  Transfer  consented  to by  Landlord  in  accordance  with this
Article 13 shall be only for the Permitted Use and for no other  purpose.  In no
event shall any Transfer  release or relieve Tenant or any  Guarantors  from any
obligations under this Lease.

         E. Notwithstanding anything to the contrary contained in this Lease, no
assignment  of Tenant's  interest in this Lease shall be binding  upon  Landlord
unless the assignee  shall execute and deliver to Landlord an agreement  whereby
such assignee agrees  unconditionally  to be personally  bound by and to perform
all of the  obligations of Tenant  hereunder and further  expressly  agrees that
notwithstanding  such assignment the provisions of this paragraph shall continue
to be binding  upon such  assignee  with respect to all future  assignments  and
transfers.  A failure or refusal of such  assignee to execute or deliver such an
agreement  shall not release the assignee from its liability for the obligations
of Tenant hereunder assumed by acceptance of the assignment of this Lease.

14.      LIENS.

         Tenant will not permit any mechanic's liens or other liens to be placed
upon the Premises or Tenant's leasehold interest therein,  the Building,  or the
Property.  Landlord's  title to the Building and Property is and always shall be
paramount to the interest of Tenant,  and nothing herein contained shall empower
Tenant to do any act that can, shall or may encumber  Landlord's  title.  In the
event any such lien does attach, Tenant shall, within twenty (20) days of notice
of the  filing  of said  lien,  either  discharge  or bond over such lien to the
satisfaction of Landlord and Landlord's Mortgagee (as hereinafter defined),  and
in such a manner as to remove the lien as an  encumbrance  against the  Building
and Property. If Tenant shall fail to

                                       19
<PAGE>

so  discharge  or bond over such lien,  then,  in addition to any other right or
remedy of  Landlord,  Landlord  may,  but shall not be obligated to bond over or
discharge  the same.  Any  reasonable  amount  paid by  Landlord  for any of the
aforesaid purposes,  including reasonable  attorneys' fees (if and to the extent
permitted  by law) shall be paid by Tenant to Landlord  on demand as  Additional
Base Rental.  Notice is hereby  given that the Landlord  shall not be liable for
any labor or  materials  furnished or to be furnished to the Tenant upon credit,
and that no  mechanic's  or  materialmen's  or other  lien for any such labor or
materials shall attach to or affect the reversionary or other estate or interest
of the Landlord in and to the Land and  Building.  No contractor of Tenant shall
by virtue of its contract be entitled to assert any mechanic's  lien against the
Building or land appurtenant thereto.

15.      INDEMNITY.

         A. Except for the  negligent  or willful acts or omissions of Landlord,
its  members,  principals,   beneficiaries,   partners,   officers,   directors,
employees, Mortgagee(s) and agents, and the respective principals and members of
any such agents  (collectively  the "Landlord  Related  Parties"),  Tenant shall
indemnify,  defend and hold Landlord and the Landlord  Related Parties  harmless
against  and from all  liabilities,  obligations,  damages,  penalties,  claims,
costs,  charges  and  expenses  (collectively  "Claims"),   including,   without
limitation,  reasonable  attorneys' fees and other  professional fees (if and to
the  extent  permitted  by law),  which may be  imposed  upon,  incurred  by, or
asserted  against Landlord or any of the Landlord Related Parties that (1) arise
from or in connection with the possession, use, occupancy,  management,  repair,
maintenance or control of the Premises,  Storage Space or the Parking Garage, or
any portion thereof, by Tenant or any party claiming by, through or under Tenant
or (2) arise from or in connection with the possession,  use or occupancy of any
of the  Limited  Common  Areas or any  portion  thereof,  by Tenant or any party
claiming by, through or under Tenant,  including, to the extent applicable under
this subsection 2, all such Claims resulting by reason of any injury or death to
persons  or  damage to  property  or (3) arise  from or in  connection  with any
willful  or  negligent  act or  omission  of Tenant  or any of its  transferees,
agents, servants,  contractors,  employees, customers, licensees or invitees, or
(4) result  from any failure on the part of Tenant to perform or comply with any
of the covenants,  agreements,  terms or conditions contained in this Lease with
which  Tenant  must  comply or  perform,  or (5) arise  from  injury or death to
persons or damage to property  sustained in the Premises,  the Parking Garage or
the Storage  Space leased by Tenant,  or (6) arise from  Tenant's  installation,
maintenance,  repair,  use or removal of any rooftop satellite or antenna dishes
or related  equipment.  In case any  action or  proceeding  is  brought  against
Landlord  or  any  of the  Landlord  Related  Parties  by  reason  of any of the
foregoing,  Tenant shall,  at Tenant's sole cost and expense,  resist and defend
such action or  proceeding  with counsel  approved by Landlord or, at Landlord's
option,  reimburse  Landlord  for the cost of any counsel  retained  directly by
Landlord to defend and resist such action or proceeding.

         B.

         C.

16.      TENANT'S INSURANCE.

         A. At all times  commencing on and after the earlier of the Preliminary
Commencement  Date or the date Tenant or its agents,  employees  or  contractors
enters the  Premises for any purpose,  Tenant shall carry and  maintain,  at its
sole cost and expense:

                  (1) Commercial General Liability  Insurance  applicable to the
Premises,  the  Parking  Garage,  the  Storage  Space  and  their  appurtenances
providing, on an occurrence

                                       20
<PAGE>

basis, a minimum  combined single limit of Two Million Dollars  ($2,000,000.00),
with a contractual liability endorsement covering Tenant's indemnity obligations
under this Lease.

                  (2) All Risk of Physical Loss Insurance written at replacement
cost value and with a  replacement  cost  endorsement  covering  all of Tenant's
Property in the Premises, the Storage Space and the Parking Garage.

                  (3) Workers'  Compensation  Insurance as required by the state
in which the Premises is located and in amounts as may be required by applicable
statute,   and   Employers'   Liability   Coverage   of  One   Million   Dollars
($1,000,000.00) per occurrence.

                  (4) Whenever  good  business  practice  indicates  the need of
additional insurance coverage or different types of insurance in connection with
the  Premises or Tenant's  use and  occupancy  thereof,  and similar  tenants of
similar  properties  in the  Bethesda,  Maryland  area are then  being  required
generally to obtain such  additional  insurance  coverage or different  types of
insurance, Tenant shall, upon request, obtain such insurance at Tenant's expense
and provide Landlord with evidence thereof.

         B. Except for  construction  items for which  Landlord  is  responsible
under this Lease, before any repairs, alterations,  additions,  improvements, or
construction  are  undertaken by or on behalf of Tenant,  Tenant shall carry and
maintain, at its expense, or Tenant shall require any contractor performing work
on the Premises to carry and maintain, at no expense to Landlord, in addition to
workers'  compensation  insurance as required by the  jurisdiction  in which the
Building is located,  All Risk  Builder's  Risk  Insurance  in the amount of the
replacement cost of any  alterations,  additions or improvements (or such lesser
amount  reasonably  required  by  Landlord)  and  Commercial  General  Liability
Insurance  (including,  without  limitation,  Contractor's  Liability  coverage,
Contractual Liability coverage and Completed Operations coverage), written on an
occurrence  basis with a minimum  combined  single limit of Two Million  Dollars
($2,000,000.00)  and adding the  "owner(s)  of the  Building  and its (or their)
respective members, principals,  beneficiaries,  partners, officers,  directors,
employees,   agents  (and  their   respective   members  and   principals)   and
mortgagee(s)"  (and any other  designees  of  Landlord  as the  interest of such
designees shall appear) as additional insureds.

         C. Any  company  writing  any  insurance  which  Tenant is  required to
maintain or cause to be maintained pursuant to the terms of this Lease (all such
insurance  as well as any other  insurance  pertaining  to the  Premises  or the
operation  of  Tenant's   business   therein  being  referred  to  as  "Tenant's
Insurance"),  as well as the  form of such  insurance,  shall  at all  times  be
subject to Landlord's reasonable approval, and each such insurance company shall
if rated by A.M.  Best,  have an A.M.  Best  rating of "A-" or better.  Any such
insurance company shall be licensed and lawfully permitted to do business in the
state in which  the  Premises  is  located.  All  policies  evidencing  Tenant's
Insurance  (except for  Workers'  Compensation)  shall  specify  Tenant as named
insured and the "owner(s) of the Building and its (or their) respective members,
principals, beneficiaries, partners, officers, directors, employees, agents (and
their  respective  members  and  principals)  and  mortgagee(s)"  (and any other
designees  of  Landlord  as the  interest  of such  designees  shall  appear) as
additional  insureds.  Provided  that the  coverage  afforded  Landlord  and any
designees of Landlord shall not be reduced or otherwise adversely affected,  all
of  Tenant's  Insurance  may be  carried  under a blanket  policy  covering  the
Premises and any other of Tenant's locations. All policies of Tenant's Insurance
shall contain  endorsements  that the  insurer(s)  will give to Landlord and its
designees  at least  thirty  (30) days'  advance  written  notice of any change,
cancellation,  termination  or lapse of said  insurance.  Tenant shall be solely
responsible for payment of premiums for all of Tenant's Insurance.  Tenant shall
deliver  to  Landlord  at least  fifteen  (15) days  prior to the time  Tenant's
Insurance is first required to be carried by Tenant,  and upon renewals at least
five (5) business

                                       21
<PAGE>

days prior to the  expiration of any such insurance  coverage,  a certificate of
insurance of all policies  procured by Tenant in compliance with its obligations
under this  Lease.  The limits of  Tenant's  Insurance  shall in no event  limit
Tenant's liability under this Lease.

         D.

         E.  Tenant  shall not do or fail to do  anything  in, upon or about the
Premises  which  will:  (1)  violate  the terms of any of  Landlord's  insurance
policies;   or  (2)  prevent  Landlord  from  obtaining  policies  of  insurance
reasonably  acceptable to Landlord or any Mortgagees.  If Tenant fails to obtain
the insurance  coverage  required by this Lease, and such failure  continues for
more than ten (10) days after  Tenant's  receipt of written  notice thereof from
Landlord,  Landlord may, at its option,  obtain such  insurance for Tenant,  and
Tenant shall pay, as Additional  Base Rental,  the cost of all premiums  thereon
and all of Landlord's reasonable costs associated therewith.

17.      SUBROGATION.

         Notwithstanding  anything  set  forth in this  Lease  to the  contrary,
Landlord and Tenant do hereby waive any and all right of recovery, claim, action
or  cause  of  action   against   the  other,   their   respective   principals,
beneficiaries,  partners, officers,  directors, agents, and employees, and, with
respect to Landlord, its Mortgagee(s),  for any loss or damage that may occur to
Landlord  or Tenant or any party  claiming  by,  through  or under  Landlord  or
Tenant,  as the  case  may  be,  with  respect  to  their  respective  property,
interruption of their  respective  business,  the Building,  the Property or the
Premises or any addition or improvements  thereto,  or any contents therein,  by
reason of fire, the elements or any other cause,  regardless of cause or origin,
including the negligence of Landlord or Tenant, or their respective  principals,
beneficiaries,  partners,  officers,  directors,  agents and employees and, with
respect to Landlord,  its  Mortgagee(s),  which loss or damage is (or would have
been,  had the  insurance  required  by this  Lease  been  carried)  covered  by
insurance.  Since this mutual  waiver will  preclude the  assignment of any such
claim by  subrogation  (or  otherwise)  to an  insurance  company  (or any other
person), Landlord and Tenant each agree to give each insurance company which has
issued, or in the future may issue,  policies of insurance,  with respect to the
items covered by this waiver, written notice of the terms of this mutual waiver,
and to have such insurance policies properly endorsed, if necessary,  to prevent
the invalidation of any of the coverage  provided by such insurance  policies by
reason of such mutual  waiver.  For the  purpose of the  foregoing  waiver,  the
amount  of any  deductible  applicable  to any loss or  damage  shall be  deemed
covered by, and  recoverable by the insured under the insurance  policy to which
such  deductible  relates.  In  the  event  that  Tenant  is  permitted  to  and
self-insures any risk which would have been covered by the insurance required to
be carried by Tenant  pursuant to Article 16 of the Lease, or if Tenant fails to
carry any insurance  required to be carried by Tenant  pursuant to Article 16 of
this  Lease,  then all loss or damage to Tenant,  its  leasehold  interest,  its
business, its property, the Premises or any additions or improvements thereto or
contents  thereof  shall be deemed  covered by and  recoverable  by Tenant under
valid and  collectible  policies  of  insurance.  In the event that  Landlord is
permitted  to and  self-insures  any risk which  would have been  covered by the
insurance  required  to be carried  by  Landlord  pursuant  to Article 18 of the
Lease,  or if Landlord  fails to carry any  insurance  required to be carried by
Landlord  pursuant  to  Article  18 of this  Lease,  then all loss or  damage to
Landlord, its business, its property, the Land, the Building or any additions or
improvements  thereto  or  contents  thereof  shall  be  deemed  covered  by and
recoverable by Landlord under valid and collectible policies of insurance.

                                       22
<PAGE>

18.      LANDLORD'S INSURANCE.

         A.       Throughout the Lease Term, Landlord shall carry and maintain:

                  (1) Commercial General Liability  Insurance  applicable to the
Property and its  appurtenances  providing,  on an occurrence  basis,  a minimum
combined single limit of Two Million Dollars ($2,000,000.00), with a contractual
liability  endorsement  covering  Landlord's  indemnity  obligations  under this
Lease.

                  (2) All Risk of Physical Loss Insurance written at replacement
cost  value  and with a  replacement  cost  endorsement  covering  the  Property
(including all Leasehold  Improvements  to the Premises and the Parking  Garage)
and all of Landlord's personal property on the Property.

The cost of such  insurance  shall be  included  as a part of the  Basic  Costs.
Payments for losses and recoveries  under  Landlord's All Risks of Physical Loss
Insurance  shall be made  solely to Landlord  or the  Mortgagees  of Landlord as
their  interests  shall appear.  All policies of Landlord's  Commercial  General
Liability  Insurance  shall specify  Landlord as the named insured and Tenant as
Additional Insured.

         B. Any company  writing  any  insurance  which  Landlord is required to
maintain or cause to be maintained pursuant to the terms of this Lease (all such
insurance  as well as any other  insurance  pertaining  to the  Property  or the
operation of  Landlord's  business  with respect  thereto  being  referred to as
"Landlord's  Insurance"),  as well as the form of such  insurance,  shall at all
times be  subject  to  Tenant's  reasonable  approval,  and each such  insurance
company if rated by A.M. Best,  shall have an A.M. Best rating of "A-" or better
and shall be  licensed  and  lawfully  permitted  to do business in the state in
which the Property is located.  Each  insurance  policy shall contain only those
deductible amounts as designated on Exhibit L attached hereto and made a part of
this  Lease  (such  amounts   being   referred  to  herein  as  the  "Base  Year
Deductibles").  Notwithstanding  the foregoing,  in the event  subsequent to the
Base  Year,   Tenant  requests  Landlord  to  increase  any  of  the  Base  Year
Deductibles,  Landlord  agrees to do so,  provided  that in the event a claim is
thereafter made,  Tenant shall pay to Landlord within thirty (30) days following
written  demand  the  amount  by which  the  deductible  exceeds  the Base  Year
Deductible. The obligation of Tenant to reimburse Landlord for any such increase
of the Base Year  Deductible  shall  expressly  survive any  termination of this
Lease with respect to any claim  arising by reason of an act,  event or omission
during the Lease Term.  Provided that the coverage  afforded Tenant shall not be
reduced or otherwise  adversely  affected,  all of  Landlord's  Insurance may be
carried  under a blanket  policy  covering the  Property  and other  property of
Landlord.  All policies of Landlord's  Insurance shall contain endorsements that
the  insurer(s)  will give to Tenant at least thirty (30) days' advance  written
notice of any  change,  cancellation,  termination  or lapse of said  insurance.
Landlord  shall  deliver to Tenant at least  fifteen (15) days prior to the time
Landlord's  Insurance  is first  required  to be carried by  Landlord,  and upon
renewals  at  least  fifteen  (15)  days  prior  to the  expiration  of any such
insurance  coverage,  a  certificate  of insurance  of all policies  procured by
Landlord in  compliance  with its  obligations  under this Lease.  The limits of
Landlord's  Insurance  shall in no event limit  Landlord's  liability under this
Lease.

         C. If Landlord fails to obtain the insurance  coverage required by this
Lease,  and such failure  continues for more than ten (10) days after Landlord's
receipt of written notice thereof from Tenant, Tenant may, at its option, obtain
such insurance for Landlord.  In such event,  Landlord shall pay the cost of all
premiums thereon (which cost shall be included in Basic Costs) and Landlord,  at
its  sole  expense,  shall  pay  all of  Tenant's  reasonable  costs  associated
therewith.

                                       23
<PAGE>

19.      CASUALTY DAMAGE.

         If the Premises or any part  thereof  shall be damaged by fire or other
casualty,  Tenant shall give prompt written notice thereof to Landlord.  In case
(i) Landlord will not be permitted by applicable  law to rebuild the Building in
substantially  the same form as existed  prior to the fire or casualty,  or (ii)
the Premises has been materially damaged and there is less than two (2) years of
the Lease Term (as extended by any Extension  Terms  exercised as of the date of
the casualty) remaining on the date of such casualty, or (iii) there shall occur
any material uninsured loss to the Building, either (x) Landlord or (y) provided
the damage did not result by reason of any willful  misconduct  of Tenant or any
of its invitees,  agents, employees,  contractors or licensees,  Tenant, may, at
its option, terminate this Lease by notifying the other party in writing of such
termination  within thirty (30) days after the date of such casualty;  provided,
however,  that if Tenant exercises any then remaining Extension Term within such
thirty (30) day period, then Landlord shall not have the right to terminate this
Lease  under  (ii)  above  as a  result  of such  casualty,  and any  notice  of
termination  theretofore given by Landlord shall be void. Such termination shall
be effective as of the date of fire or casualty,  with respect to any portion of
the  Premises  that  was  rendered  untenantable,  and  the  effective  date  of
termination  specified in Landlord's or Tenant's termination notice (which shall
be no less than ninety (90) days after the date of such notice), with respect to
any portion of the Premises that remained  tenantable.  If neither  Landlord nor
Tenant elects to terminate this Lease,  Landlord shall commence and proceed with
reasonable diligence to restore the Building and the Leasehold Improvements (but
excluding any improvements, alterations or additions made by Tenant in violation
of this Lease) located within the Premises to  substantially  the same condition
they were in immediately prior to the happening of the casualty. Notwithstanding
the foregoing,  Landlord's  obligation to restore the Building and the Leasehold
Improvements   shall  not  require  Landlord  to  expend  for  such  repair  and
restoration work the insurance  proceeds  actually received by the Landlord as a
result of the casualty or which would have been received had Landlord  continued
in full force and effect the insurance required of Landlord hereunder.  Further,
any  proceeds of insurance  received by  Landlord's  mortgagee or ground  lessor
shall be deemed  received by Landlord for purposes  hereof.  When repairs to the
Premises have been completed by Landlord,  Tenant shall complete the restoration
or  replacement  of  all  Tenant's   Property   necessary  to  permit   Tenant's
re-occupancy of the Premises. Landlord shall not be liable for any inconvenience
or annoyance to Tenant or injury to the business of Tenant  resulting in any way
from such damage or the repair thereof,  except that Landlord shall allow Tenant
a fair  diminution of Rent on a per diem basis (based on the ratio of the square
foot area of the  untenantable  portion of the Premises to the total square foot
area of the  Premises)  during  the time and to the  extent  any  damage  to the
Premises  or the means of access  thereto  causes the  Premises  to be  rendered
untenantable and not used by Tenant except to the extent provided in the case of
a Tenant Caused Casualty (below defined). Such diminution of Rent shall continue
until the first to occur of (i) resumption of use and occupancy by Tenant of the
damaged portion for the conduct of its business  operations  thereon or (ii) the
last to occur of (x)  substantial  completion  by  Landlord  of its  repair  and
restoration  of the  Premises  or (y)  substantial  completion  by Tenant of its
repair and  restoration,  not to exceed however under this subsection (y) ninety
(90) days  following  the date of  substantial  completion  by  Landlord  of its
repairs and  restoration.  In the case of damage or  destruction  affecting less
than the entire Premises but rendering  Tenant unable to reasonably  conduct its
business in the remaining undamaged portion, then any abatement of rent to which
Tenant  shall be entitled  hereunder  shall be extended to the entire  Premises.
Notwithstanding  the  foregoing,  if the  Premises  or any other  portion of the
Building is damaged by fire or other  casualty  resulting from the negligence of
Tenant or any Tenant Related  Parties (herein a "Tenant Caused  Casualty"),  the
Rent  hereunder  shall not be  diminished  during  any period  during  which the
Premises, or any portion thereof, is untenantable (except to the extent Landlord
is or  would  be  entitled  to be  reimbursed  by the  proceeds  of  any  rental
interruption insurance either carried by Landlord or which is

                                       24
<PAGE>

generally available to commercial landlords owning large modern office buildings
within the Washington, D.C. metropolitan area). Landlord and Tenant hereby waive
the  provisions  of any law from time to time in effect  during  the Lease  Term
relating  to the effect upon  leases of partial or total  destruction  of leased
property. Landlord and Tenant agree that their respective rights in the event of
any damage to or  destruction of the Premises  shall be those  specifically  set
forth herein.

20.      INTENTIONALLY OMITTED

21.      CONDEMNATION.

         If (a) the whole or any  substantial  part of the  Premises  or (b) any
portion of the  Building or Property  which  would  leave the  remainder  of the
Building  unsuitable for use as an office building  comparable to its use on the
Commencement  Date,  shall be taken or condemned for any public or  quasi-public
use under  governmental  law,  ordinance or  regulation,  or by right of eminent
domain, or by private purchase in lieu thereof,  then Landlord or Tenant may, at
its option, terminate this Lease effective as of the date the physical taking of
said  Premises or said portion of the Building or Property  shall occur.  In the
event this Lease is not  terminated,  the Rentable Area of the Premises shall be
appropriately  adjusted,  and  Landlord,  at  its  expense,  shall  restore  the
remaining  Premises to a complete,  tenantable unit. In the event of a taking or
condemnation  of the Parking  Garage,  if such taking or condemnation is of less
than all of such Parking Garage, the Parking Garage Rental shall be appropriated
adjusted,  and Landlord, at its expense,  shall restore the remaining portion of
the Parking Garage.  In addition,  Rent for any portion of the Premises so taken
or condemned (or Parking  Garage  Rental for any portion of the Parking  Garage)
shall be abated  during  the  unexpired  term of this Lease  effective  when the
physical  taking of said portion of the Premises shall occur.  All  compensation
awarded for any such taking or  condemnation,  or sale proceeds in lieu thereof,
shall be the property of Landlord,  and Tenant shall have no claim thereto,  the
same being hereby  expressly  waived by Tenant,  except for any portions of such
award or  proceeds  which are  specifically  allocated  by a court of  competent
jurisdiction  for the taking of or damage to trade fixtures of Tenant,  Tenant's
moving  expenses or any other  damages  personal to Tenant as  determined by the
court which if paid to Tenant will not reduce the award to which  Landlord would
in the  absence of such  payment be  entitled  to claim for its  account,  which
proceeds Tenant specifically reserves to itself.

22.      EVENTS OF DEFAULT.

         The following events shall be deemed to be events of default under this
Lease:

         A. Tenant shall fail to pay when due any Base Rental,  Additional  Base
Rental or other Rent under this Lease and such  failure  shall  continue for ten
(10) days after written notice from Landlord (hereinafter  sometimes referred to
as a "Monetary Default").

         B. Any failure by Tenant (other than a Monetary Default) to comply with
any term,  provision or covenant of this Lease,  including,  without limitation,
the rules and  regulations,  which  failure is not cured within thirty (30) days
after delivery to Tenant of notice of the occurrence of such failure,  provided,
however,  that if the failure identified is incapable of being cured within such
thirty (30) day period for reasons  which are beyond the  reasonable  control of
Tenant,  then  such  thirty  (30)  day cure  period  shall  be  extended  for an
additional  reasonable  amount of time necessary for Tenant to effect such cure,
as long as Tenant  proceeds  diligently  to effect such cure upon its receipt of
Landlord's  written  notice,  and  provided,  further,  that if any such failure
creates a hazardous condition, such failure must be cured immediately.

                                       25
<PAGE>

         C. Tenant or any Guarantor shall make a transfer in fraud of creditors,
or shall commit an act of bankruptcy or shall make an assignment for the benefit
of creditors, or Tenant or any Guarantor shall admit in writing its inability to
pay its debts as they become due.

         D. Tenant or any Guarantor  shall file a petition  under any section or
chapter  of the  United  States  Bankruptcy  Code,  as  amended,  pertaining  to
bankruptcy,  or under any  similar  law or statute  of the United  States or any
State  thereof,  or  Tenant  or any  Guarantor  shall be  adjudged  bankrupt  or
insolvent in proceedings filed against Tenant or any Guarantor thereunder;  or a
petition or answer  proposing the  adjudication  of Tenant or any Guarantor as a
debtor or its  reorganization  under any  present  or  future  federal  or state
bankruptcy  or  similar  law shall be filed in any court  and such  petition  or
answer shall not be discharged  or denied  within one hundred  twenty (120) days
after the filing thereof.

         E. A receiver or trustee  shall be appointed  for all or  substantially
all of the assets of Tenant or any  Guarantor  or of the  Premises  or of any of
Tenant's  Property  located  thereon in any proceeding  brought by Tenant or any
Guarantor,  or any such receiver or trustee shall be appointed in any proceeding
brought  against Tenant or any Guarantor and shall not be discharged  within one
hundred  twenty (120) days after such  appointment  or Tenant or such  Guarantor
shall consent to or acquiesce in such appointment.

         F. The leasehold  estate hereunder shall be taken on execution or other
process of law or equity in any action against Tenant.

         G. The liquidation,  termination, dissolution or forfeiture of right to
do business of Tenant or any Guarantor.

23.      REMEDIES.

         A. Upon the  occurrence  of any event or events of  default  under this
Lease,  for so long as such event(s) of default are  continuing,  Landlord shall
have the option in its sole and  exclusive  discretion to pursue any one or more
of the following remedies, using appropriate legal proceedings,  but without any
notice (except as expressly prescribed in Article 22 above) or demand whatsoever
(and  without   limiting  the  generality  of  the   foregoing,   Tenant  hereby
specifically  waives notice and demand for payment of Rent or other  obligations
due [except as expressly  prescribed  in Article 22 above or elsewhere  in, this
Lease] and waives any and all other  notices or demand  requirements  imposed by
applicable law):

                  (1)  Terminate  this  Lease,   in  which  event  Tenant  shall
immediately surrender the Premises to Landlord. If Tenant fails to surrender the
Premises upon termination of the Lease hereunder, Landlord may without prejudice
to any other remedy  which it may have,  enter upon and take  possession  of the
Premises  and expel or remove  Tenant and any other  person who may be occupying
said Premises,  or any part thereof, and Tenant hereby agrees to pay to Landlord
on demand the amount of all loss and damage which  Landlord may suffer by reason
of such  termination,  whether  through  inability  to  relet  the  Premises  on
satisfactory terms or otherwise,  specifically  including but not limited to all
Costs of Reletting  (hereinafter  defined) and any deficiency  that may arise by
reason of any reletting or failure to relet.

                  (2) Enter upon and take  possession  of the Premises and expel
or remove Tenant or any other person who may be occupying said Premises,  or any
part  thereof,  without  having any civil or  criminal  liability  therefor  and
without  terminating this Lease.  Landlord may (and shall following  recovery of
exclusive use and possession of the Premises from Tenant use reasonable  efforts
to) relet the  Premises or any part  thereof  for the account of Tenant,  in the
name of Tenant or Landlord or otherwise, without notice to Tenant, for such term
or terms

                                       26
<PAGE>

which  may be  greater  or less  than the  period  which  would  otherwise  have
constituted  the  balance  of the Lease Term and on such  conditions  (which may
include  concessions,  free rent and  alterations  of the Premises) and for such
uses as Landlord in its  absolute  discretion  may  determine,  and Landlord may
collect and receive any rents  payable by reason of such  reletting.  Reasonable
efforts  to  relet  shall  be  as  determined  by  Landlord  in  its  reasonable
discretion;  recognizing, however, that Landlord shall not be required hereunder
to lease the  Premises  prior to leasing any other  office  space in the Project
available for lease to others and that Landlord  shall be fully entitled to take
into  consideration  expansion  requirements  or needs of its other  tenants  in
making  decisions  with  respect  to the  duration  or other  conditions  of any
reletting.  Tenant  agrees to pay Landlord on demand all Costs of Reletting  and
any  deficiency  that may arise by reason of such reletting or failure to relet.
Landlord  shall  not be  responsible  or  liable  for any  failure  to relet the
Premises or any part thereof or for any failure to collect any rent due upon any
such reletting, provided that Landlord uses reasonable efforts to relet as above
provided,  and to collect such rent. No such re-entry or taking of possession of
the Premises by Landlord shall be construed as an election on Landlord's part to
terminate  this Lease unless a written  notice of such  termination  is given to
Tenant.

                  (3) After two (2) days  written  notice to Tenant,  enter upon
the Premises  without having any civil or criminal  liability  therefor,  and do
whatever  Tenant is  obligated  to do under the terms of this Lease,  and Tenant
agrees to reimburse Landlord on demand for any reasonable expense which Landlord
may incur in thus  affecting  compliance  with Tenant's  obligations  under this
Lease together with interest at a per annum rate equal to the Maximum Rate.

                  (4) In order to regain  possession of the Premises and to deny
Tenant  access  thereto in any instance in which  Landlord has  terminated  this
Lease or Tenant's  right to  possession,  or to limit  access to the Premises in
accordance  with local law in the event of a default by Tenant,  Landlord or its
agent may, at the expense and  liability  of the Tenant,  alter or change any or
all locks or other security devices  controlling  access to the Premises without
posting  or  giving  notice  of any  kind  to  Tenant.  Landlord  shall  have no
obligation  to provide  Tenant a key or grant  Tenant  access to the Premises so
long as Tenant is in default  under this Lease.  Tenant shall not be entitled to
recover possession of the Premises, terminate this Lease, or recover any actual,
incidental,  consequential,  punitive,  statutory  or other  damages or award of
attorneys'  fees,  by reason of  Landlord's  alteration or change of any lock or
other security device.  Landlord may, without notice,  remove and either dispose
of or store, at Tenant's expense,  any property belonging to Tenant that remains
in the  Premises  after  Landlord  has regained  possession  thereof;  provided,
however,  that Landlord  shall grant the owner of any property  leased by Tenant
access to the Premises to remove such property.

                  (5)  Terminate  this  Lease,  in  which  event,  Tenant  shall
immediately  surrender  the Premises to Landlord and pay to Landlord the sum of:
(a) all Rent  accrued  hereunder  through  the date of  termination,  and,  upon
Landlord's  determination  thereof,  (b) an amount equal to: the total Rent that
Tenant  would  have been  required  to pay for the  remainder  of the Lease Term
discounted  to present  value at the Prime  Rate then in effect,  minus the then
present fair rental  value of the Premises for the  remainder of the Lease Term,
similarly  discounted,  after deducting all  anticipated  Costs of Reletting (as
defined below).

         B. For purposes of this Lease, the term "Costs of Reletting" shall mean
all costs and expenses  incurred by Landlord in connection with the reletting of
the Premises,  including without limitation,  the cost of cleaning,  renovation,
repairs,  decoration and alteration of the Premises for a new tenant or tenants,
advertisement,  marketing,  brokerage and  reasonable  legal fees (if and to the
extent  permitted  by law),  the cost of  protecting  or caring for the Premises
while  vacant,  the cost of removing  and storing  any  property  located on the
Premises,

                                       27
<PAGE>

any increase in insurance premiums caused by the vacancy of the Premises and any
other  out-of-pocket  expenses incurred by Landlord including tenant incentives,
allowances and inducements.

         C. Except as otherwise herein provided,  no repossession or re-entering
of the Premises or any part  thereof  pursuant to Article 23 hereof or otherwise
shall  relieve  Tenant  or any  Guarantor  of its  liabilities  and  obligations
hereunder,  all  of  which  shall  survive  such  repossession  or  re-entering.
Notwithstanding any such repossession or re-entering by reason of the occurrence
of an event of default, Tenant will pay to Landlord the Rent required to be paid
by Tenant pursuant to this Lease.

         D. No right or remedy herein  conferred upon or reserved to Landlord is
intended to be exclusive of any other right or remedy,  and each and every right
and remedy  shall be  cumulative  and in  addition  to any other right or remedy
given hereunder or now or hereafter existing by agreement,  applicable law or in
equity. In addition to other remedies provided in this Lease,  Landlord shall be
entitled, to the extent permitted by applicable law, to injunctive relief, or to
a decree compelling performance of any of the covenants, agreements,  conditions
or provisions of this Lease,  or to any other remedy  allowed to Landlord at law
or in equity.  Forbearance  by Landlord  to enforce one or more of the  remedies
herein  provided  upon an event of default  shall not be deemed or  construed to
constitute a waiver of such default.

         E. This  Article 23 shall be  enforceable  to the  maximum  extent such
enforcement is not prohibited by applicable law, and the unenforceability of any
portion thereof shall not thereby render unenforceable any other portion.

24.      LIMITATION OF LIABILITY.

         NOTWITHSTANDING  ANYTHING TO THE CONTRARY  CONTAINED IN THIS LEASE, THE
LIABILITY OF LANDLORD (AND OF ANY SUCCESSOR LANDLORD  HEREUNDER) TO TENANT SHALL
BE LIMITED TO THE  INTEREST OF LANDLORD IN THE  BUILDING,  AND TENANT  AGREES TO
LOOK SOLELY TO  LANDLORD'S  INTEREST  IN THE  BUILDING  FOR THE  RECOVERY OF ANY
JUDGMENT OR AWARD AGAINST THE LANDLORD,  IT BEING INTENDED THAT NEITHER LANDLORD
NOR  ANY  MEMBER,  PRINCIPAL,   PARTNER,   SHAREHOLDER,   OFFICER,  DIRECTOR  OR
BENEFICIARY  OF  LANDLORD  SHALL  BE  RERSONALLY  LIABLE  FOR  ANY  JUDGMENT  OR
DEFICIENCY. TENANT HEREBY COVENANTS THAT, PRIOR TO THE FILING OF ANY SUIT FOR AN
ALLEGED DEFAULT BY LANDLORD HEREUNDER, IT SHALL GIVE LANDLORD AND ALL MORTGAGEES
WHOM  TENANT HAS BEEN  NOTIFIED  HOLD  MORTGAGES  OR DEED OF TRUST  LIENS ON THE
PROPERTY,  BUILDING OR PREMISES  NOTICE AND REASONABLE TIME TO CURE SUCH ALLEGED
DEFAULT BY LANDLORD.

25.      NO WAIVER.

         Failure of Landlord or Tenant to declare any default  immediately  upon
its  occurrence,  or delay in taking any action in  connection  with an event of
default shall not  constitute a waiver of such default,  nor shall it constitute
an estoppel  against such party,  but such party shall have the right to declare
the  default at any time and take such action as is lawful or  authorized  under
this Lease.  Failure by Landlord or Tenant to enforce its rights with respect to
any one default shall not  constitute a waiver of its rights with respect to any
subsequent  default.  Receipt by Landlord of Tenant's keys to the Premises shall
not constitute an acceptance or surrender of the Premises.

                                       28
<PAGE>

 26.     EVENT OF BANKRUPTCY.

         In addition  to, and in no way  limiting  the other  remedies set forth
herein,  Landlord  and Tenant agree that if Tenant ever becomes the subject of a
voluntary  or  involuntary  bankruptcy,  reorganization,  composition,  or other
similar type  proceeding  under the federal  bankruptcy  laws, as now enacted or
hereinafter amended (collectively an "Event of Bankruptcy"), then:

         A.  "Adequate  protection"  of  Landlord's  interest  in  the  Premises
pursuant to the provisions of Section 361 and 363 (or their successor  sections)
of the Bankruptcy Code, 11 U.S.C.  Section 101 et seq., (such Bankruptcy Code as
amended from time to time being herein  referred to as the  "Bankruptcy  Code"),
prior to assumption and/or assignment of the Lease by Tenant shall include,  but
not be limited to all (or any part) of the following:

                  (1) the continued payment by Tenant of the Base Rental and all
other Rent due and owing  hereunder and the  performance of all other  covenants
and obligations hereunder by Tenant;

                  (2) the furnishing of an  additional/new  security  deposit by
Tenant in the amount of the two (2) times the then current monthly Base Rental.

         B.  "Adequate  assurance of future  performance"  by Tenant  and/or any
assignee of Tenant pursuant to Bankruptcy Code Section 365 will include (but not
be limited to) payment of an  additional/new  Security  Deposit in the amount of
three (3) times the then current monthly Base Rental payable hereunder.

         C. Any person or entity to which this Lease is assigned pursuant to the
provisions of the Bankruptcy  Code,  shall be deemed without further act or deed
to have assumed all of the obligations of Tenant arising under this Lease on and
after the  effective  date of such  assignment.  Any such assignee  shall,  upon
demand by  Landlord,  execute and deliver to Landlord an  instrument  confirming
such assumption of liability.

         D. Notwithstanding  anything in this Lease to the contrary, all amounts
payable by Tenant to or on behalf of the Landlord  under this Lease,  whether or
not expressly denominated as "Rent," shall constitute "rent" for the purposes of
Section 502(b) (6) of the Bankruptcy Code.

         E. If this Lease is  assigned  to any person or entity  pursuant to the
provisions of the Bankruptcy  Code,  any and all monies or other  considerations
payable or otherwise to be  delivered  to Landlord  (including  Base Rentals and
other Rent  hereunder),  shall be and remain the exclusive  property of Landlord
and shall not  constitute  property  of  Tenant or of the  bankruptcy  estate of
Tenant.  Any and all  monies  or other  considerations  constituting  Landlord's
property under the preceding sentence not paid or delivered to Landlord shall be
held in trust by  Tenant  or  Tenant's  bankruptcy  estate  for the  benefit  of
Landlord and shall be promptly paid to or turned over to Landlord.

         F. If Tenant  assumes  this  Lease  and  proposes  to  assign  the same
pursuant to the  provisions of the  Bankruptcy  Code to any person or entity who
shall have made a bona fide offer to accept an assignment of this Lease on terms
acceptable to the Tenant, then notice of such proposed offer/assignment, setting
forth:  (1) the name and address of such person or entity,  (2) all of the terms
and  conditions  of such offer,  and (3) the  adequate  assurance to be provided
Landlord to assure such person's or entity's future performance under the Lease,
shall be given to  Landlord  by  Tenant no later  than  twenty  (20) days  after
receipt  by  Tenant,  but in any event no later  than ten (10) days prior to the
date that Tenant shall make application to a court of competent jurisdiction for
authority and approval to enter into such assumption and

                                       29
<PAGE>

assignment,  and Landlord shall thereupon have the prior right and option, to be
exercised by notice to Tenant given at any time prior to the  effective  date of
such  proposed  assignment,  to accept an assignment of this Lease upon the same
terms and  conditions and for the same  consideration,  if any, as the bona fide
offer made by such persons or entity, less any brokerage commission which may be
payable out of the consideration to be paid by such person for the assignment of
this Lease.

27.      WAIVER OF JURY TRIAL.

         Landlord  and Tenant  hereby  waive any right to a trial by jury in any
action or  proceeding  based upon,  or related  to, the  subject  matter of this
Lease. This waiver is knowingly, intentionally, and voluntarily made by Landlord
and Tenant,  and each party  acknowledges  that  neither the other party nor any
person acting on behalf of the other party has made any  representations of fact
to induce  this  waiver of trial by jury or in any way to modify or nullify  its
effect.  Landlord  and  Tenant  each  further  acknowledges  that  it  has  been
represented  (or has had the  opportunity to be  represented)  in the signing of
this  Lease and in the  making  of this  waiver by  independent  legal  counsel,
selected of its own free will,  and that it has had the  opportunity  to discuss
this waiver with counsel.

28.      CONSTRUCTION OF THE PREMISES.

         A. Landlord,  at Landlord's sole cost and expense,  shall construct the
"Base  Building",  and the  Common  Areas,  in  accordance  with the  plans  and
specifications prepared by Landlord's architect described on Exhibit G (the Base
Building  Plans  and   Specifications),   and  in  compliance   with  all  legal
requirements and all matters of record affecting the Property. All materials and
equipment to be  incorporated  into the Base  Building and Common Areas shall be
new and of good quality and in good operating condition,  and construction shall
be  free  from  faults  and  defects.   Construction  not  conforming  to  these
requirements  shall be corrected.  Tenant shall be entitled to obtain changes to
the Base Building  Plans and  Specifications  by reason of Tenant's  request for
either  additional or  substituted  items within the Base  Building,  (the "Base
Building  Upgrades").  All  costs  (including  without  limitation  all  design,
engineering  and  construction  costs)  which  Landlord  shall  incur to design,
implement or furnish the Base  Building  Upgrades  shall be at the sole cost and
expense of Tenant. Tenant shall be entitled to direct that Landlord apply either
or both the  improvement  Allowance or  improvement  Loan to the payment of Base
Building  Upgrades.  Attached hereto as Exhibit M is the Workletter dealing with
the  performance  of the Base Building,  Base Building  Upgrades and the Initial
Leasehold Improvements.

         B.

         C.

         D.

         E.

         F.  If  Landlord's  Contractor  is  selected  to  perform  the  Initial
Leasehold  Improvements,  such work shall be performed,  at Tenant's expense, in
accordance with the following provisions of this Section 28.F:

                  (1) Landlord  shall  contract with  Landlord's  Contractor for
performance of the Initial Leasehold Improvements.  In addition,  Landlord shall
be responsible for obtaining the

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<PAGE>

construction  permits for the  Initial  Leasehold  Improvements  and the use and
occupancy permits for the Premises.

                  (2) All materials and  equipment to be  incorporated  into the
Initial  Leasehold  Improvements  shall be new and of good  quality  and in good
operating  condition,  and  construction  shall be free from faults and defects.
Construction not conforming to these requirements shall be corrected.

                  (3) Tenant shall be given  access to the  Premises  during the
period when Landlord is constructing the Initial Leasehold Improvements, for the
purpose of  installing  telephone  and  computer  cabling and  equipment,  other
special  equipment,  fixtures and  furniture  therein,  provided that (i) Tenant
shall  coordinate  such  installations  with  Landlord's  Contractor,  (ii) such
installations  shall  not  unreasonably  impede,   hinder  or  delay  Landlord's
completion  of the  Base  Building  or the  Initial  Leasehold  Improvements  or
obtaining  a use and  occupancy  permit for the  Premises,  (iii)  Tenant  shall
maintain  the  liability  insurance  coverage  required by this Lease,  and (iv)
Tenant  shall  indemnify  Landlord  against  any and all  damages  sustained  in
connection  with the  installation  of such  furniture,  fixtures and equipment,
unless  such  damage  is caused  by the  negligence  or  willful  misconduct  of
Landlord, its agents, employees or contractors.

                  (4)

         G.  If  Tenant  elects  to  have  the  Initial  Leasehold  Improvements
performed  by Tenant's  Contractor,  such work shall be  performed,  at Tenant's
expense, in accordance with the following provisions of this Section 28.G:

                  (1)  Tenant  shall  contract  with  Tenant's   Contractor  for
performance of the Initial Leasehold Improvements.  In addition, Tenant shall be
responsible  for obtaining the  construction  permits for the Initial  Leasehold
Improvements and the use and occupancy permits for the Premises.

                  (2)  All  contractors  performing  such  construction  must be
licensed to perform such work in the State of Maryland, and such contractors, or
Tenant, must maintain all insurance required by Section 16.B of this Lease.

                  (3) Such  construction  shall be performed in accordance  with
the Leasehold  Improvement Plans and Specifications,  and in compliance with all
legal  requirements  and all  matters  of record  affecting  the  Property.  All
materials  and  equipment  to  be  incorporated   into  the  Initial   Leasehold
Improvements  shall be new and of good quality and in good operating  condition,
and  construction  shall be free  from  faults  and  defects.  Construction  not
conforming to these requirements shall be corrected.  Landlord shall be entitled
to oversee all construction by Tenant hereunder in order to assure compliance by
Tenant of the approved plans and specifications.

                  (4) Tenant  shall  indemnify  Landlord  against (i) any damage
sustained in connection with the work performed by any  contractors  retained by
Tenant,  unless such damage is caused by  negligence  or willful  misconduct  of
Landlord,  its agents,  employees or  contractors,  and (ii) any  mechanics'  or
materialmen's  liens against the Premises or the Building  arising from the work
performed by any contractors retained by Tenant.

                  (5)  Landlord  shall  pay  any  portion  of  the   Improvement
Allowance  and the  Improvement  Loan  (if  any)  remaining  after  payment  for
architect's charges pursuant to Section

                                       31
<PAGE>

28.D to Tenant,  in  installments  made  payable  jointly to Tenant and Tenant's
Contractor  equal to the sum of invoices for  completed  portions of the Initial
Leasehold Improvements submitted by Tenant to Landlord,  within thirty (30) days
after  Landlord's  receipt of such  invoices,  together  with  waivers from such
contractors,  subcontractors  and material suppliers of any lien rights same may
have for such  completed  portions of the Initial  Leasehold  Improvements.  Any
amount which is not paid when due pursuant to this  Section  28.G(5)  shall bear
interest at the Maximum Rate from the date due until paid.

29.      HOLDING OVER.

         In the absence of a written  agreement  executed by Landlord  expressly
recognizing  that such agreement shall prevail over the provisions  contained in
this  Article 29, in the event of holding  over by Tenant  after  expiration  or
other  termination of this Lease or in the event Tenant  continues to occupy the
Premises  after the  termination  of Tenant's  right of  possession  pursuant to
Articles  22  and 23  hereof,  occupancy  of the  Premises  subsequent  to  such
termination  or expiration  shall be that of a tenancy at  sufferance  and in no
event for  month-to-month  or  year-to-year,  but Tenant shall,  throughout  the
entire holdover period, be subject to all the terms and provisions of this Lease
and  shall  pay for its  use  and  occupancy  an  amount  equal  to one  hundred
twenty-five  percent  (125%) of the Base  Rental due for the period  immediately
preceding such holding over, plus any Additional  Base Rental due hereunder.  No
holding  over by Tenant or  payments  of money by Tenant to  Landlord  after the
expiration of the term of this Lease shall be construed to extend the Lease Term
or prevent  Landlord  from  recovery of immediate  possession of the Premises by
summary  proceedings or otherwise;  provided,  however,  that Landlord shall not
unreasonably  withhold  its consent to a holdover  tenancy not to exceed  ninety
(90) days;  provided,  however that Landlord shall not be required to consent to
any  holdover  in the event that such  holdover  impairs  Landlord's  ability to
tender  all or any  substantial  (i.e.  more  than  one-fourth)  portion  of the
Premises  under a replacement  lease.  In addition to the  obligation to pay the
amounts set forth above during a holdover period, in the event Tenant holds over
without the express prior written  consent from Landlord,  the Tenant also shall
be liable to  Landlord  for all  actual  (but not  consequential)  damage  which
Landlord  may suffer by reason of any holding  over by Tenant,  and Tenant shall
indemnify  Landlord  against  any and all  claims  made by any  other  tenant or
prospective  tenant  against  Landlord  for  delay  by  Landlord  in  delivering
possession of the Premises to such other tenant or prospective tenant.

30.      SUBORDINATION TO MORTGAGES.

         Tenant accepts this Lease subject and subordinate to any mortgage, deed
of trust,  ground lease or other lien  presently  existing or hereafter  arising
upon the Premises, or upon the Building and/or the Property and to any renewals,
modifications,  refinancings and extensions thereof (any such mortgage,  deed of
trust,  lease  or  other  lien  being  sometimes  hereinafter  referred  to as a
"Mortgage",  and the person or entity having the benefit of same being sometimes
referred to hereinafter as a "Mortgagee").  Tenant agrees upon demand to execute
such  further   instruments   subordinating   this  Lease,   acknowledging   the
subordination  of this Lease or attorning to the holder of any such  Mortgage as
Landlord may reasonably  request.  If any person shall succeed to all or part of
Landlord's interests in the Premises whether by purchase,  foreclosure,  deed in
lieu of foreclosure,  power of sale,  termination of lease or otherwise,  Tenant
shall, without charge, attorn to such successor-in-interest.

         This  subordination  provision with respect to ground leases is subject
to the  express  condition  that so long as Tenant is not in default  beyond any
applicable  cure period in the payment of Base Rental or Additional  Base Rental
or any other material covenant or condition

                                       32
<PAGE>

of this  Lease,  (i) its rights as Tenant  hereunder  shall not be  affected  or
terminated, (ii) its possession of the Premises shall not be disturbed, (iii) no
action or proceeding shall be commenced to remove or evict Tenant,  and (iv) the
Lease shall at all times continue in full force and effect  notwithstanding  the
termination  or  expiration  of such  ground  lease prior to the  expiration  or
termination  of this Lease (or if  terminated  by law as a result of  Landlord's
interest  being  terminated,  the ground lessor will enter into a new lease with
Tenant with the identical terms and conditions of this Lease).

         This  subordination  provision  with  respect to  mortgages or deeds of
trust is  subject  to the  express  condition  that so long as  Tenant is not in
default in the payment of Base Rental or Additional  Base Rental or of any other
material  covenants and conditions of this Lease, its rights as Tenant hereunder
shall  not be  terminated  and  its  possession  of the  Premises  shall  not be
disturbed by any mortgagee or trustee or by any  proceedings  on the debts which
any such  mortgage  or deed of trust  secures  or by  virtue of a right or power
contained  in any such  mortgage  or deed of  trust or the bond or note  secured
thereby and that any sale at foreclosure shall be subject to this Lease.

         Landlord shall obtain for Tenant, from the holder of each ground lease,
mortgage  and  deed of  trust  now or  hereafter  encumbering  the  Building,  a
Non-Disturbance  Agreement in form  acceptable  to  Landlord's  ground lessor or
mortgagee,  and  reasonably  satisfactory  to Tenant,  confirming the statements
hereinabove  set forth in this section.  Tenant  expressly  recognizes  that the
holder  under any such  Non-Disturbance  Agreement  shall be  entitled to except
therefrom  any  obligations  under  Section 40 below  pertaining to the Adjacent
Building or Section 42 pertaining to rights of first  offering.  Landlord agrees
to use reasonable efforts to obtain the agreement from the holder of each ground
lease,  mortgage and deed of trust now or hereafter  encumbering the Building to
both notify Tenant of any default by Landlord under such ground lease,  mortgage
or deed of trust and to accept the cure by Tenant of such default.

         Tenant  agrees that any  Mortgagee  shall have the right at any time to
subordinate  such  Mortgage  to this  Lease on such  terms and  subject  to such
conditions as such Mortgagee may deem  appropriate in its  discretion,  provided
the  Mortgagee  for  itself  and any party  claiming  by,  through or under such
Mortgagee  agrees in  writing  to  recognize  this Lease in the event it or such
party acquires the Building by foreclosure or deed-in-lieu of foreclosure.

         Tenant  waives the  provisions  of any  statute or rule of law,  now or
hereafter  in  effect,  which may give or  purport  to give  Tenant any right to
terminate or otherwise adversely affect this Lease and the obligations of Tenant
hereunder in the event that any such  foreclosure  proceeding  is  prosecuted or
completed.  Tenant  agrees to give any  Mortgagee,  by  certified  mail,  return
receipt  requested,  a copy of any  notice  of  default  served  upon  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  mortgagees  and/or  trust deed  holders.  Tenant  further  agrees  that if
Landlord  shall have failed to cure such default within the time provided for in
this  Lease,  then the  mortgagees  and/or  trust  deed  holders  shall  have an
additional thirty (30) 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,
not to exceed an  additional  ninety (90) days, if within such thirty (30) days,
the mortgagee and/or trust deed holder 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 this Lease shall not be terminated  while such remedies are being so
diligently pursued. Tenant agrees that in the event of the sale of the Property,
by foreclosure or deed in lieu thereof, the purchaser at such sale shall only be
responsible for the return of any Security Deposit paid by Tenant to Landlord in
connection with this Lease to the extent that

                                       33
<PAGE>

such purchaser  actually receives such Security  Deposit.  Tenant further agrees
that any successor to Landlord's  interest shall not be bound by (i) any payment
of monthly Base Rental or Additional  Base Rental for more than one (1) month in
advance,  except  prepayments  in the nature of security for the  performance by
Tenant of its obligations under this Lease or (ii) any amendment or modification
of this  Lease  made  after  Tenant's  receipt  of the name and  address  of any
Landlord's Mortgagee, without the consent of such Mortgagee.

31.      ATTORNEYS' FEES.

         In the event that Landlord should retain counsel and institute any suit
against Tenant for violation of or to enforce any of the covenants or conditions
of this Lease,  or should Tenant  retain  counsel and institute any suit against
Landlord for violation of any of the  covenants or conditions of this Lease,  or
should  either  party  intervene  in any suit in which  the  other is a party to
enforce or protect its interest or rights  hereunder,  the prevailing  party (as
determined by the court in which the suit is  instituted) in any such suit shall
be entitled to all of its costs, expenses and reasonable fees of its attorney(s)
(if and to the extent permitted by law) in connection therewith.

32.      NOTICE.

         Whenever any demand,  request,  approval,  consent or notice ("Notice")
shall or may be given to either of the  parties by the other,  each such  Notice
shall be in  writing  and shall be sent by  registered  or  certified  mail with
return  receipt  requested,  or sent by messenger or overnight  courier  service
(such as Federal Express) at the respective addresses of the parties for notices
as set forth in  Section  I.A(9).  of this  Lease,  provided  that if Tenant has
vacated the Premises,  Landlord may serve Notice by any manner permitted by law.
Any Notice under this Lease  delivered by registered or certified  mail shall be
deemed to have been given,  delivered,  received and effective on the earlier of
(a) the third  Business Day  following the day on which the same shall have been
mailed with sufficient postage prepaid or (b) the delivery date indicated on the
return receipt.  Notice sent by messenger or overnight  courier service shall be
deemed  given,  delivered,  received and  effective  upon the day such notice is
actually  received,  as  indicated on the receipt  obtained by the  messenger or
overnight  courier  service.  Either  party may, at any time,  change its Notice
Address by giving the other party  Notice  stating the change and setting  forth
the new address.

33.      ESTOPPEL CERTIFICATES.

         Landlord  and  Tenant  each  agrees,  at any time and from time to time
during  the Term of this  Lease,  upon not less than  fifteen  (15)  days  prior
written notice by the other party,  to execute,  acknowledge  and deliver to the
other party a statement  certifying to  substantially  the following  provisions
(recognizing  that any of such statement may be modified by the certifying party
to  reflect  the then  state of  facts):  (i) a  statement  that  this  Lease is
unmodified  and in full force and  effect (or if there have been  modifications,
that  the  Lease is in full  force  and  effect  as  modified  and  stating  the
modifications),  (ii) a  statement  of the dates to which the Rent and any other
charges hereunder have been paid by Tenant, (iii) a statement of whether or not,
to the best knowledge of the certifying  party, the other party is in default in
the performance of any covenant, agreement or condition contained in this Lease,
and if so,  specifying each such default of which the certifying  party may have
knowledge,  (iv) a statement of the address to which  notices to the  certifying
party should be sent,  (v) a statement that all work required to be performed by
the Landlord  under this Lease has been  completed  and that Tenant has accepted
the Premises and improvements  therein and/or that all payments of the Allowance
have been  satisfied by Landlord,  (vi) a statement that Tenant will not attempt
to terminate this Lease by

                                       34
<PAGE>

reason of Landlord's  default or omission  without giving written notice of such
default or omission to Landlord and any  mortgagee of which Tenant has knowledge
and/or (vi) such other  statement or statements  as the  requesting  party,  any
prospective purchaser of the Property, any mortgagee or prospective mortgagee of
the Property or of Landlord's  interest in either,  any prospective  assignee of
any such mortgagee and/or any prospective  assignee of Tenant's interest in this
Lease or  prospective  subtenant  of Tenant  may  reasonably  request.  Any such
statement  delivered  pursuant  hereto,  may be relied  upon by any owner of the
Property,   any  prospective  purchaser  of  the  Property,   any  mortgagee  or
prospective  mortgagee of the Property or of Landlord's  interest in either, any
prospective  assignee  of any such  mortgagee  or any  prospective  assignee  of
Tenant's interest in this Lease or prospective subtenant of Tenant.

         Tenant agrees to make such reasonable  changes or modifications to this
Lease as may be  required  by any  mortgagee  of the  Building  and/or the Land,
provided  that such  changes or  modifications  shall not increase the amount of
Base Rental, Additional Base Rental, shorten the Term of this Lease or change or
redefine the Premises,  or otherwise  adversely affect the rights or obligations
of the parties hereunder.

34.      ACCESS TO ROOF.

         A. Landlord  shall not install,  nor permit any other party to install,
any  satellite or antenna  dishes on the roof of the  Building.  Throughout  the
Term,  Landlord  shall  permit  Tenant  to  install  and  maintain,  subject  to
applicable  Laws and the provisions of this Article 34, one or more satellite or
antenna dishes on the roof of the Building ("Tenant's Roof Use").

         B.  Landlord  shall make  available to Tenant  access to and  locations
mutually  acceptable  to Landlord  and Tenant on the roof for the  construction,
installation,  maintenance,  repair,  operation  and  use of such  satellite  or
antenna  dishes.  Tenant shall screen such  installations  in a manner  mutually
acceptable  to Landlord and Tenant.  Tenant  shall be entitled to remove,  or if
designated  by Landlord at the time of its consent,  Tenant shall be required to
remove,  any such satellite or antenna dishes and any related equipment from the
Building at the expiration or other  termination of the Term of this Lease,  and
Tenant  shall be  required  at its sole cost and  expense to make all  necessary
repairs or restoration  resulting  occasioned by such removal.  Tenant shall pay
all costs associated with the installation,  maintenance, repair, use, insurance
and removal of such satellite or antenna dishes and any related equipment.

         C. Tenant shall give Landlord  reasonable  telephonic notice before any
entry  onto  the  roof  of  the  Building  by  Tenant's  agents,   employees  or
contractors,  and shall  permit  Landlord's  agents or  employees  to  accompany
Tenant's  agents,  employees  or  contractors  on any such  entry onto the roof.
Except as otherwise hereinafter set forth in this Article 34, Landlord shall not
be liable for any claims,  losses,  actions,  damages,  liabilities  or expenses
arising from any satellite or antenna dishes or related  equipment  installed by
Tenant on the roof of the Building,  or the installation,  maintenance,  repair,
use or  removal of such  dishes  and  related  equipment,  unless  caused by the
negligence  or  willful  misconduct  of  Landlord,  its  agents,   employees  or
contractors.

         D. Tenant shall obtain Landlord's written consent prior to installation
of any satellite or antenna  dishes or other roof-top  equipment,  which consent
shall not be unreasonably delayed or withheld, with respect to the type, weight,
method of  installation  and  appearance  of all such items.  Landlord  shall be
entitled to condition its consent to the  installation  of such load supports as
Landlord may  reasonably  determine  necessary to support the proposed  roof-top
equipment.   Tenant  shall  provide  Landlord  with  plans  and   specifications
sufficient for such purposes. Tenant will obtain prior to installation,  any and
all governmental licenses, approvals

                                       35
<PAGE>

necessary for the installation,  maintenance and use of any equipment  installed
pursuant to this  Article 34.  Tenant's  Roof Use shall not in any way  conflict
with any applicable Laws. Tenant shall indemnify and hold Landlord harmless from
and  against  any and all  loss,  cost  (including  reasonable  attorney's  fees
incurred  in  defending  Landlord),  damage  or  liability  arising  out  of any
violation by Tenant's Roof Use of any applicable Laws. The provisions  contained
in Sections 10 and 16 shall fully  govern all roof-top  installations  by Tenant
hereunder.

         E. Tenant's Roof Use shall be exercised: (1) in such manner as will not
create any hazardous  condition or interfere with or impair the operation of the
heating, ventilation, air conditioning,  plumbing,  electrical, fire protection,
life,  safety,  public utilities or other systems or facilities in the Building;
(2) in  such a  manner  as  will  not  unreasonably  interfere  with  Landlord's
operation or  maintenance  of the Building or the operations of other tenants of
the Project located in the Adjacent  Building;  (3) at Tenant's cost,  including
the cost of repairing any damage to the Building and any personal  injury and/or
property damage caused by the installation, inspection, adjustment, maintenance,
removal or  replacement  of any of Tenant's  equipment on the roof; and (4) in a
manner which will not void or  invalidate  any roof warranty then in effect with
respect to the roof of the Building.

         To the extent that Tenant shall cause any wiring or cabling (including,
without limitation,  any and all supporting structures) to be installed,  pulled
or   operated   in   the   Premises   (including,    without   limitation,   any
telecommunications  equipment  installed  by reason of  Tenant's  Roof Use) such
wiring or cabling,  and  supporting  structures  at  Landlord's  option shall be
removed (provided  Landlord advised Tenant in writing at the time of its consent
to the  installation  of such  wiring  and  cabling  that  such  items are to be
removed),  and  the  Building  restored  by  Tenant  at  Tenant's  expense  upon
expiration or earlier  termination of this Lease,  or as reasonably  required by
Landlord.

         In the event Tenant  shall elect to permit a third party not  occupying
in the Building at least 1,000  square feet of rentable  area to use any portion
of the roof for the  placement  of any devices or other  equipment,  then and in
such event  Tenant  agrees to cause such third  party  subtenant  or licensee to
remove all wiring and cabling  servicing  such third party's roof top devices or
other equipment, together with all such devices and equipment. Landlord shall be
entitled to notify Tenant to cause such removal at Landlord's option, at anytime
prior to thirty (30) days following the termination or expiration of this Lease.
Any damage  caused to the roof or  Building by reason of such  removal  shall be
promptly repaired or restored at Tenant's sole cost and expense. The obligations
of Tenant  hereunder shall expressly  survive such  termination or expiration of
this Lease.

35.      EXCEPTED RIGHTS.

         Except as  otherwise  set forth  herein,  this Lease does not grant any
rights to light or air over or about the Building. Landlord specifically excepts
and  reserves  to itself such areas  within the  Premises  as are  required  for
installation of utility lines and the right to maintain and repair the same, and
no rights with  respect  thereto are  conferred  upon  Tenant  unless  otherwise
specifically provided herein. Landlord further reserves to itself the right from
time to  time:  (a) to make  any  alterations,  additions,  improvements  to the
Building,  or any part thereof  (including the Premises) which are necessary for
the safety, protection, preservation or improvement of the Building or which are
approved by Tenant,  or as Landlord  may be required to do by law; (b) to retain
at all times and to use pass-keys to all locks within and into the Premises; and
(c) to approve the weight,  size, or location of heavy  equipment or articles in
and about the Premises.  Landlord,  in accordance with Article 12 hereof,  shall
have the right to enter the Premises in  connection  with the exercise of any of
the rights set forth herein and such entry into the

                                       36
<PAGE>

Premises  and the  performance  of any  work  therein  shall  not  constitute  a
constructive eviction or entitle Tenant to any abatement or reduction of Rent by
reason thereof.

36.      SURRENDER OF PREMISES.

         At the  expiration  or earlier  termination  of this Lease or  Tenant's
right of possession hereunder, Tenant shall remove all Tenant's Property and all
Required  Removables  from the Premises and quit and  surrender  the Premises to
Landlord,  broom clean, and in good order,  condition and repair,  ordinary wear
and tear and  casualty  damage not  required to be repaired by Tenant  hereunder
excepted.  If Tenant  fails to remove any of Tenant's  Property  within five (5)
days  after  the  termination  of this  Lease or  Tenant's  right to  possession
hereunder, Landlord, at Tenant's sole cost and expense, shall be entitled, after
two (2) business  days  written  notice to Tenant,  to remove  and/or store such
Tenant's  Property and Landlord shall in no event be responsible  for the value,
preservation or safekeeping thereof. Tenant shall pay Landlord, upon demand, any
and all  expenses  caused by such removal and all storage  charges  against such
property so long as the same shall be in the possession of Landlord or under the
control  of  Landlord.  In  addition,  if Tenant  fails to remove  any  Tenant's
Property  from the Premises or storage,  as the case may be, within ten (10)days
after written notice from Landlord, Landlord, at its option, may deem all or any
part of such  Tenant's  Property  to have been  abandoned  by  Tenant  and title
thereof shall immediately pass to Landlord.

37.      PARKING GARAGE.

         A. Prior to the Preliminary  Commencement Date, Landlord, at Landlord's
expense,  shall  construct  on the  subsurface  levels of the Building a parking
garage capable of  accommodating at least four hundred (400) parking spaces (the
"Parking  Garage"),  in  accordance  with plans and  specifications  approved by
Tenant.   It  is  understood   that  the  Parking   Garage  shall  be  completed
substantially similar to the garage existing as of the date of this Lease in the
Adjacent  Building,  and tendered in broom-clean  condition  (i.e., the finished
concrete, striping (if desired by Tenant), painting, lighting,  sprinklering and
exhaust fans in place shall all be similar to that which is  presently  provided
at the  Adjacent  Building,  including  also the finished  elevator  lobbies but
excluding  all gates,  booths,  and other  equipment  typically  utilized in the
operation of a parking  garage).  Throughout  the Lease Term,  Tenant shall have
exclusive use of the Parking  Garage,  and Tenant shall pay Landlord the Parking
Garage  Rental,  as Additional  Base Rental.  The Parking Garage Rental shall be
payable in equal monthly  installments  during the Lease Term,  commencing as of
the Preliminary Commencement Date.

         B.  Throughout  the Lease Term,  Tenant,  at its sole cost and expense,
shall  operate  and  maintain  the  Parking  Garage,  and shall make all repairs
thereto and perform all  maintenance  therein  required in order to maintain the
Parking Garage in good operating condition (including  re-painting,  restriping,
re-sealing,  re-tubing all light fixtures, performing all repairs to the lights,
light fixtures, gates and doors therein and all ventilation,  drainage, fire and
life safety equipment  servicing the Parking Garage) unless  necessitated by the
negligent act or omission of Landlord, or any agent,  employee, or contractor of
Landlord.  Landlord  shall not be responsible to perform or provide any services
whatsoever  in or for the  Parking  Garage,  other than  structural  repairs not
caused by reason of any act or omission of Tenant or any Tenant Related Parties.
Throughout the Lease Term, Landlord shall make any repairs to the Parking Garage
which are the  responsibility  of Landlord under the two  immediately  preceding
sentences.  Tenant  shall  operate the  Parking  Garage in  compliance  with all
applicable Laws.  Tenant, at its discretion,  may employ one or more independent
contractors to assist Tenant in the  performance of its  obligations  under this
section.

                                       37
<PAGE>

         Tenant  will not cause the  Property to incur the Parking Tax levied by
Montgomery  County  Maryland  pursuant to Montgomery Co. Code Chapter 60 Section
60.1 et.  seq.,  as same may be  hereafter  amended,  supplemented  or replaced.
Notwithstanding the foregoing, Tenant shall be entitled to change the use of the
first  floor  portion  of  the  Premises  to a use  which  would  result  in the
imposition  of the  Parking  Tax  provided  both (x)  Tenant is able to  provide
assurances reasonably acceptable to Landlord confirming that upon termination of
this Lease and the cessation of the use proposed by Tenant, the Property will no
longer incur the Parking Tax, and (y) Tenant shall bear the entire  Parking Tax,
and any other costs or expenses  resulting by reason of the  imposition  of same
against the Property.

         C. The use of the Parking Garage and the elevator vestibules  servicing
the Parking Garage by Tenant and Tenant's visitors, invitees and licensees shall
be at their  sole risk and  expense,  and in no event  shall  Landlord  have any
liability  for damage to, theft or loss of property of the Tenant or of Tenant's
employees,  visitors,  licensees  or invitees  suffered or sustained in or about
said parking areas or elevator  vestibules.  Further, in no event shall Landlord
have any liability for any injury or death  occurring  within the Parking Garage
or such  vestibules  unless caused by the  negligence  or willful  misconduct of
Landlord. Tenant shall indemnify and hold Landlord harmless from all such claims
in  accordance  with  Section  15.A above.  The Parking  Garage and all security
therefore  shall be under the  exclusive  control of Tenant,  who shall have the
right to  establish  rules  and  regulations  governing  the use of the  Parking
Garage,  and the right to change such rules and  regulations  from time to time,
and the right to limit or terminate  the right of any parties to use the Parking
Garage.

         D. If the Parking  Garage is damaged or  destroyed  by  casualty,  then
unless the Premises is also damaged or destroyed by such casualty and this Lease
is  terminated as a result  thereof,  Landlord  shall  commence and proceed with
reasonable  diligence to restore the Parking  Garage to  substantially  the same
condition it was in immediately prior to the happening of the casualty. Landlord
shall not be liable for any  inconvenience  or  annoyance to Tenant or injury to
the  business  of Tenant  resulting  in any way from such  damage or the  repair
thereof,  except that Landlord  shall allow Tenant a fair  diminution of Parking
Garage Rental on a per diem basis (based on the ratio of the square foot area of
the unusable  portion of the Parking Garage to the total square foot area of the
Parking  Garage)  during the time and to the  extent  any damage to the  Parking
Garage or the means of access  thereto  causes the Parking Garage to be rendered
unusable and not used by Tenant.

         E.  On the  Termination  Date,  Tenant  shall  remove  all of  Tenant's
Property from the Parking Garage and surrender the Parking Garage to Landlord in
broom clean, "as is" condition.

38.      ACCESS.

         Tenant  shall  have  access  to the  Premises  and the  Parking  Garage
twenty-four  (24) hours per day, seven (7) days per week (subject,  however,  to
the reasonable  rules and regulations  established from time to time by Landlord
for the Building).  Access to the Building  entrance outside the Normal Business
Hours will be by means of a security card access system and/or a guard system or
other system or arrangement  as  established  from time to time by Landlord with
Tenant's approval, which may be granted or withheld in Tenant's sole discretion.
There  will be a minimum of one (1)  elevator  in  operation  for  Tenant's  use
outside of the Normal Business Hours.  Notwithstanding  anything to the contrary
in this Lease,  Tenant  shall have the right to restrict  access to the Building
(including  also  the  entrance  from the  plaza  area) by  parties  other  than
Landlord, its agents, employees and contractors, and Tenant, its subtenants, and
their respective agents, employees, contractors, licensees and invitees.

                                       38
<PAGE>

39.      OPTION TO EXTEND.

40.      EXPANSION SPACE.

41.      MISCELLANEOUS.

         A. If any term or provision of this Lease, or the  application  thereof
to any person or circumstance shall, to any extent, be invalid or unenforceable,
the  remainder of this Lease,  or the  application  of such term or provision to
persons or  circumstances  other  than  those as to which it is held  invalid or
unenforceable,  shall not be affected  thereby,  and each term and  provision of
this Lease shall be valid and enforced to the fullest  extent  permitted by law.
This Lease  represents the result of negotiations  between  Landlord and Tenant,
each of which has been (or has had  opportunity to be) represented by counsel of
its own  selection,  and neither of which has acted under duress or  compulsion,
whether legal,  economic or otherwise.  Consequently,  Landlord and Tenant agree
that the language in all parts of the Lease shall in all cases be construed as a
whole  according  to its fair  meaning  and  neither  strictly  for nor  against
Landlord or Tenant.

         B.  Tenant  agrees not to record  this Lease or any  memorandum  hereof
without   Landlord's  prior  written   consent,   which  consent  shall  not  be
unreasonably  withheld in the case of a proposed  memorandum  (as opposed to the
Lease itself),  recognizing that any such recordation  shall be at the sole cost
and  expense of Tenant,  and in the event  thereof,  Tenant  shall  execute  and
deliver to Landlord within ten (10) days following any termination of this Lease
at no cost or expense to Landlord a memorandum of termination in recordable form
evidencing the termination of such memorandum.

         C. This Lease and the  rights and  obligations  of the  parties  hereto
shall be interpreted, construed, and enforced in accordance with the laws of the
state in which the Building is located.

         D. Events of "Force Majeure" shall include strikes, riots, acts of God,
shortages  of  labor  or  materials,   war,  governmental  law,  regulations  or
restrictions  and any other  cause  whatsoever  that is beyond  the  control  of
Landlord  or  Tenant,  as the case may be.  Whenever  a period of time is herein
prescribed for the taking of any action by Landlord or Tenant,  such party shall
not be  liable  or  responsible  for,  and  there  shall  be  excluded  from the
computation  of such period of time,  any delays due to events of Force Majeure.
In no event shall either  party claim Force  Majeure with respect to any payment
obligation hereunder.

         E. Landlord shall have the right to transfer and assign, in whole or in
part,  all of its rights  and  obligations  hereunder  and in the  Building  and
Property referred to herein, and in such event and upon such transfer,  Landlord
shall be released from any obligations  hereunder accruing after the date of the
transfer,  and Tenant  agrees to look  solely to such  successor  in interest of
Landlord for the performance of such obligations.

         F. Tenant hereby represents to Landlord that it has dealt directly with
and only with the  party[ies]  designated  as the Broker under Section 1 of this
Lease as the broker[s] in connection with this Lease. Tenant agrees to indemnify
and hold Landlord and the Landlord  Related Parties  harmless from all claims of
any other brokers  claiming to have  represented  Tenant in connection with this
Lease.  Landlord  agrees to  indemnify  and hold  Tenant and the Tenant  Related
Parties  harmless  from all claims of any brokers  claiming to have  represented
Landlord in connection with this Lease. Landlord agrees to compensate the Broker
in

                                       39
<PAGE>

accordance with the terms of a separate  written  agreement  heretofore  entered
into by and between Landlord and the Broker.

         G. If there is more than one Tenant,  or if the Tenant is  comprised of
more than one person or entity,  the obligations  hereunder  imposed upon Tenant
shall  be joint  and  several  obligations  of all such  parties.  All  notices,
payments, and agreements given or made by, with or to any one of such persons or
entities shall be deemed to have been given or made by, with or to all of them.

         H.  In the  event  Tenant  is a  corporation  (including  any  form  of
professional  association),  partnership (general or limited),  or other form of
organization other than an individual (each such entity is individually referred
to herein as an "Organizational Entity"), then Tenant hereby covenants, warrants
and represents: (1) that such individual is duly authorized to execute or attest
and deliver this Lease on behalf of Tenant in accordance with the organizational
documents of Tenant and has been duly appointed as the  attorney-in-fact for the
Tenant;  (2) that this Lease is binding  upon  Tenant;  (3) that  Tenant is duly
organized  and  legally  existing  in  the  state  of its  organization,  and is
qualified to do business in the state in which the Premises is located;  and (4)
that the  execution  and delivery of this Lease by Tenant will not result in any
breach of, or  constitute a default under any  mortgage,  deed of trust,  lease,
loan, credit agreement, partnership agreement or other contract or instrument to
which Tenant is a party or by which Tenant may be bound.  If Tenant or Guarantor
is an  Organizational  Entity,  upon  request,  Tenant  or such  Guarantor  will
concurrent with execution of this Lease or Guaranty, as the case may be, deliver
to Landlord  copies of an  appropriate  resolution  or consent of such  entity's
board of directors or other appropriate  governing body authorizing or ratifying
the  execution  and delivery of this Lease or Guaranty,  as  appropriate,  which
resolution or consent will be duly  certified to Landlord's  satisfaction  by an
appropriate  individual  with authority to certify such  documents,  such as the
secretary or assistant  secretary or the managing  general  partner of Tenant or
Guarantor.  Tenant  and its  Guarantor  shall also  provide to  Landlord a legal
opinion from its counsel (which at Tenant's  option may be its in-house  general
counsel)  addressed to Landlord  and its lender  certifying  that all  requisite
actions  have been taken by both  Tenant and  Guarantor  in order to render this
Lease and Guaranty as valid and binding obligations of such parties, enforceable
in accordance with their terms.

         I.

         J.  Except  as  expressly  otherwise  herein  provided,  time is of the
essence of this Lease.  This Lease shall create the relationship of Landlord and
Tenant between the parties hereto.

         K. This Lease and the covenants and conditions  herein  contained shall
inure to the  benefit  of and be  binding  upon  Landlord  and  Tenant and their
respective permitted successors and assigns.

         L.  Notwithstanding  anything to the contrary  contained in this Lease,
the expiration of the Lease Term,  whether by lapse of time or otherwise,  shall
not relieve Tenant from Tenant's obligations accruing prior to the expiration of
the Lease Term, and such obligations  shall survive any such expiration or other
termination of the Lease Term.

         M. The  headings  and  titles to the  paragraphs  of this Lease are for
convenience   only  and  shall  have  no  affect   upon  the   construction   or
interpretation of any part hereof.

                                       40
<PAGE>

         N.  LANDLORD HAS  DELIVERED A COPY OF THIS LEASE TO TENANT FOR TENANT'S
REVIEW ONLY,  AND THE DELIVERY  HEREOF DOES NOT CONSTITUTE AN OFFER TO TENANT OR
OPTION.  THIS  LEASE  SHALL NOT BE  EFFECTIVE  UNTIL AN  ORIGINAL  OF THIS LEASE
EXECUTED BY BOTH LANDLORD AND TENANT AND AN ORIGINAL GUARANTY,  IF ANY, EXECUTED
BY EACH GUARANTOR IS DELIVERED TO AND ACCEPTED BY LANDLORD.

         O. Tenant shall, and may peacefully have, hold, and enjoy the Premises,
subject to the other terms of this Lease (including, without limitation, Article
30 hereof),  provided  that  Tenant  pays the Rent herein  recited to be paid by
Tenant and performs all of Tenant's  covenants and agreements  herein contained.
This covenant and any and all other  covenants of Landlord shall be binding upon
Landlord  and its  successors  only  during its or their  respective  periods of
ownership of the Landlord's interest hereunder.

         P.  Landlord  represents  and  warrants  to Tenant  that as of the date
hereof, Landlord is the fee simple owner of record (and in fact) of the Property
or has  contracted  to acquire  those  portions of the Property  not  heretofore
acquired  by  Landlord.  A copy of  Landlord's  title  insurance  policy  on the
portions of the Property  which have been  previously  acquired  together with a
copy of Landlord's Title Insurance Commitment for those portions of the Property
not presently  acquired are attached hereto as Exhibit I. Landlord shall acquire
all portions of the Property not presently  acquired  within the thirty (30) day
period following the execution of this Lease.  Within thirty (30) days following
receipt  of such  policy,  Landlord  shall  provide  Tenant a copy of its  title
insurance policy for each such portion acquired subsequent to the date hereof.

42.      RIGHT OF FIRST OFFER.

         Provided  that the Lease shall be in full force and effect,  and Tenant
shall not then be in default nor subject to any Event of Bankruptcy, and further
provided  that  Tenant has not let its right to the  particular  Extension  Term
succeeding  the term then in effect  lapse by reason of the failure of Tenant to
renew this Lease timely,  then and only in such event,  Tenant shall be entitled
to a right of first offer of the  Property  (in  accordance  with the  following
terms)  unless the rights of first  offering  hereunder  have been  extinguished
pursuant  to the  conditions  below  contained.  Such right of first offer shall
apply  if,  and only if,  Landlord  shall  desire  to sell its  interest  in the
Property,  in a transaction where neither Landlord nor any one or more partners,
members or shareholders  of Landlord,  owning or controlling in the aggregate at
least  one-third  (1/3) of all ownership  interests  therein (such parties being
collectively herein the "Remaining Members"), reasonably anticipate retainage of
a beneficial  ownership in the Property or the rents  derived  therefrom.  It is
expressly  recognized that any proposed  exchange,  sale or other disposition of
the Property to a real estate  investment trust, a Down REIT, an UPREIT or other
future entity used to hold or operate real properties,  whereunder the Remaining
Members obtain equity interests (or debt interests  convertible to equity) shall
constitute  retainage of a beneficial  ownership interest in the Property or the
rents   therefrom   (even  if  such  entity  owns  diverse  other   properties).
Consequently a transfer to such a trust,  Down REIT,  UPREIT or entity shall not
trigger the rights of first offer hereunder and all rights of Tenant  thereafter
under this section shall be totally extinguished.

         In those  circumstances  where  Tenant is  entitled  to have a right of
first  opportunity  (i.e.  an  anticipated  sale for cash of the  Property to an
unrelated  third  party  whereunder  the  Remaining  Members  will not  retain a
beneficial  interest) Tenant shall have a right of first opportunity to purchase
the Property for a purchase  price and upon terms to be mutually  agreed upon by
Landlord and Tenant.  Promptly  after deciding it wishes to sell its interest in
the Property, Landlord shall give Tenant written notice of same. Tenant may then
exercise its right of first opportunity by giving written notice of the exercise
to Landlord  within  thirty  (30) days after the date of  Landlord's  notice.  A
failure by Tenant to respond  within said thirty (30) day period  shall  totally
extinguish Tenant's right of first opportunity to purchase Landlord's interest

                                       41
<PAGE>

in the Property.  Upon receipt of notice of exercise from Tenant, Landlord shall
keep the  Property  off the  market for sixty (60)  days,  during  which  period
Landlord and Tenant shall negotiate in good faith the purchase price,  terms and
conditions  of Tenant's  purchase of  Landlord's  interest in the  Property.  If
Landlord and Tenant do not mutually  agree upon such purchase  price,  terms and
conditions  within  said  sixty  (60)  day  period,   Tenant's  right  of  first
opportunity  to purchase  Landlord's  interest in the Property  shall be totally
extinguished. Notwithstanding the foregoing, if the property proposed to be sold
includes  other portions of the Project then owned by Landlord or its affiliates
or third parties,  then Tenant may exercise its right of first  opportunity only
by agreeing to purchase all of the  portions of the Project then  proposed to be
sold.

         Tenant's  rights  hereunder  shall not be binding upon any mortgagee or
ground lessor of Landlord,  nor shall any purchase at  foreclosure or in lieu of
foreclosure be subject to the provisions of this Section.

43.      ENTIRE AGREEMENT.

         This Lease Agreement, including the following Exhibits:

         Exhibit A      -    Site Plan of Property [Section I.B(29)]
         Exhibit B      -    Outline of Premises [Section I.A(6)]
         Exhibit C      -    Rules and Regulations [Article 5]
         Exhibit D      -    Commencement Letter [Section 3.Al
         Exhibit E      -    Outline and Location of Storage Space [Section 6.A]
         Exhibit F-1    -    Building HVAC and Electricity Specifications
                             [Section 7.A.2]
         Exhibit F-2    -    Janitorial Service Specifications [Section 7.A.4]
         Exhibit G      -    Schedule of Base Building Plans and Specifications
                             [Section 28.A]
         Exhibit H
         Exhibit I      -    Title Insurance Policy and Commitment on Property
                             [Section 41.P]
         Exhibit J      -    Construction Schedule [Section 28.C]
         Exhibit K      -    Schedule of Base Rental [Section 4.B]
         Exhibit L      -    Schedule of Insurance Deductibles [Section 18.B]
         Exhibit M      -    Work Letter [Section 28.A]

constitutes the entire agreement  between the parties hereto with respect to the
subject  matter  of  this  Lease  and   supersedes  all  prior   agreements  and
understandings between the parties related to the Premises,  including all lease
proposals,  letters of intent and similar  documents.  TENANT AND LANDLORD  EACH
EXPRESSLY  ACKNOWLEDGES  AND AGREES THAT THE OTHER PARTY HAS NOT MADE AND IS NOT
MAKING,  AND SUCH PARTY,  IN EXECUTING AND DELIVERING THIS LEASE, IS NOT RELYING
UPON, ANY  WARRANTIES,  REPRESENTATIONS,  PROMISES OR STATEMENTS,  EXCEPT TO THE
EXTENT THAT THE SAME ARE EXPRESSLY SET FORTH IN THIS LEASE.  ALL  UNDERSTANDINGS
AND  AGREEMENTS  HERETOFORE  MADE  BETWEEN  THE PARTIES ARE MERGED IN THIS LEASE
WHICH ALONE FULLY AND COMPLETELY EXPRESSES THE AGREEMENT OF THE PARTIES, NEITHER
PARTY RELYING UPON ANY STATEMENT OR  REPRESENTATION  NOT EMBODIED IN THIS LEASE.
THIS LEASE MAY BE MODIFIED  ONLY BY A WRITTEN  AGREEMENT  SIGNED BY LANDLORD AND
TENANT.

                                       42
<PAGE>

         IN  WITNESS  WHEREOF,  Landlord,  acting  by both  of its  two  general
partners, and Tenant have executed this Lease as of the day and year first above
written.

WITNESS/ATTEST:                  LANDLORD:

                                 BETHESDA PLACE II LIMITED PARTNERSHIP

                                 By: 7626 Wisconsin Corp., its General Partner

                                 By:
------------------------------       -----------------------------------------

                                 By: Tower MD Holdings, LLC, its General Partner

                                 By:
------------------------------       -----------------------------------------

WITNESS:                         TENANT:

                                 U.S. GENERATING COMPANY

                                 By:
------------------------------       -----------------------------------------
                                      Authorized Officer and Attorney-In-Fact

                                       43
<PAGE>

                                   EXHIBIT "A"

                              SITE PLAN OF PROPERTY

                               [GRAPHIC OMITTED]

<PAGE>

                                   EXHIBIT "B"

                              OUTLINE OF PREMISES

<PAGE>

                                   EXHIBIT "C"

                              RULES AND REGULATIONS

1.       All keys to demised  premises  shall be  surrendered  to Landlord  upon
         termination of this Lease.

2.       Tenant will refer all  contractor's  representatives  and  installation
         technicians  rendering  any service for Tenant at the demised  premises
         affecting any of the building's systems or requiring access to the roof
         to  Landlord  before  performance  of  any  such  contractual  service.
         Tenant's  contractors and  installation  technicians  shall comply with
         Landlord's  rules  and  regulations   pertaining  to  construction  and
         installation.

3.       Tenant shall not at any time occupy any part of the demised premises or
         project as sleeping or lodging quarters.

4.       Tenant  shall  not  place or use in or about the  demised  premises  or
         project any explosives,  gasoline,  kerosene,  oil, acids, caustics, or
         any flammable,  explosive or hazardous materials,  except those used in
         Tenant  business and used,  stored and disposed of in  accordance  with
         applicable law, without written consent of Landlord.

5.       Landlord will not be responsible for lost or stolen personal  property,
         equipment,  money or jewelry  from the demised  premises or the project
         regardless  of whether or not such loss  occurs when the area is locked
         against entry.

6.       No dogs,  cats, fowl, or other animals shall be brought into or kept in
         or about the demised premises or project.

7.       Employees of Landlord shall not receive or carry messages for or to any
         Tenant or other person,  nor shall they render free or paid services to
         any Tenant, its agent, employees or invitees.

8.       None of the parking, plaza, recreation or lawn areas, entries, passages
         or doors  shall be  obstructed  with any  rubbish,  litter,  trash,  or
         material of any nature by Tenant's agents, employees or invitees at any
         time. Stairways may be unlocked if allowed by County Fire Marshall.

9.       The water  closets and other water  fixtures  shall not be used for any
         purpose  other than those for which they were  constructed.  Any damage
         resulting  to them from misuse or by the defacing or injury of any part
         of the building shall be borne by the person who shall occasion it.

10.      Nothing shall be thrown out of the windows of the building or down the
         stairways or other passages.

11.      Tenant  assumes,  and shall  indemnify  Landlord  against all risks and
         claims of damage to persons or property  arising in connection with any
         said  movement of furniture or office  supplies and equipment in or out
         of the building.

12.      Landlord  shall not be  liable  for any  damage  from the  stoppage  of
         elevators for necessary or desirable  repairs or improvements or delays
         of any sort in  connection  with the elevator  service,  provided  that
         Landlord uses  reasonable  efforts to restore full elevator  service as
         quickly as possible.

<PAGE>

13.      The use of  cement  or other  similar  adhesive  materials  not  easily
         removed with water to lay floor coverings is expressly prohibited.

14.      Tenant  agrees to cooperate  and assist  Landlord in the  prevention of
         canvassing, soliciting and peddling within the building or project.

15.      Tenant shall be entitled to establish  additional rules and regulations
         for its employees,  contractors, invitees and agents, provided same are
         not inconsistent with the foregoing.

<PAGE>

                                   EXHIBIT "D"

                               COMMENCEMENT LETTER

Date:     _________________________________

Tenant:   _________________________________

Address:  _________________________________

                  Re:  Commencement  Letter with respect to that  certain  Lease
         dated  ___________________  by and  between  Bethesda  Place II Limited
         Partnership,  as Landlord,  and U.S. GENERATING COMPANY, as Tenant, for
         ___________  square feet of Rentable  Area in the  Building  located at
         7600 Wisconsin Avenue, Bethesda, Maryland.

Dear _____________________:

         In accordance  with the terms and  conditions  of the above  referenced
Lease, Tenant hereby accepts possession of the Premises and agrees as follows:

         1.       The Commencement Date of the Lease is ___________________;

         2.       The Termination Date of the Lease is ____________________.

         Please  acknowledge  your acceptance of possession and agreement to the
terms set forth  above by  signing  all  three (3)  copies of this  Commencement
Letter in the space provided and returning two (2) fully executed  copies of the
same to my attention.

                                   Sincerely,

Agreed and Accepted:

Tenant:__________________________________

By:    __________________________________

Name:  __________________________________

Title: __________________________________

Date:  __________________________________

<PAGE>

                                   EXHIBIT "E"

                     OUTLINE AND LOCATION OF STORAGE SPACE

<PAGE>

                                  EXHIBIT "F-1"

                  BUILDING HVAC AND, ELECTRICITY SPECLFICATIONS

BETHESDA PLACE II
BETHESDA, MARYLAND
________________________________________________________________________________
BASE BUILDING INFORMATION MANUAL
________________________________________________________________________________

                               [GRAPHIC OMITTED]

FOR:
BETHESDA PLACE II LIMITED PARTNERSHIP

NOTE: THE INFORMATION  CONTAINED HEREIN IS PRELIMINARY AND SUBJECT TO AMENDMENTS
AND REFINEMENTS.

By:
KISHIMOTO.GORDON PC                                               April 15, 1998

KISHIMOTO.GORDON PC

<PAGE>

BETHESDA PLACE II BASE BUILDING INFORMATION MANUAL

TABLE OF CONTENTS
-----------------

<TABLE>
<CAPTION>
                                                                                               page no.
<S>         <C>                                                                                <C>
I.          GENERAL INFORMATION

            A.         Introduction                                                             3.
            B.         Project Location                                                         3.
            C.         General Building Descriptions                                            3.
            D.         Office Tower General Specifications                                      4.
            E.         Loading Dock Specifications                                              4.
            F.         Vertical Transportation                                                  4.

II.         CORE AND SHELL DEVELOPMENT

            A.        Introduction                                                              5.
            B.        General Interior Areas                                                    5.
            C.        Public Areas and Core Finishes                                            6.
            D.        Hardware                                                                  6.
            E.        Roofing                                                                   6.
            F.        Structural Systems                                                        6.
            G.        Mechanical Systems                                                        9.
            H.        Electrical                                                               11.
            I.        Fire/Life Safety                                                         12.
            J.        Plumbing        :                                                        14.
            K.        Telephone Service                                                        15.
            L.        Drinking Fountains                                                       15.
            M.        Window Coverings                                                         15.
            N.        Keying                                                                   15.
            O.        Mail Facilities                                                          15.
            P.        Signage                                                                  15.

III.        EXHIBITS

                      See  full  size  documents:   Approved  Project  Plan-  Optional  Method  of
                      Development: ARCHITECTURAL SCHEMATIC DESIGN PACKAGE -January 22, 1998
</TABLE>

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PROJECT DISCRIPTION OF BETHESDA PLACE II

I.       GENERAL INFORMATION

         A.       INTRODUCTION

         The  information  provided  here is current as of the date noted in the
         lower left hand corner of this page.

         B.       PROJECT LOCATION

         Bethesda Place II is located in the downtown central business  district
         of Bethesda,  Maryland at the northwest  corner of Wisconsin Avenue and
         Commerce Lane.

         Bethesda  Place  II  is  the  second  phase  of  a  premier   mixed-use
         office/residential/retail  complex within walking distance of dozens of
         restaurants and retail outlets. The project is conveniently located one
         block north of the Bethesda Metro station and one mile from the Capital
         Beltway.

         C.       GENERAL BUILDING DESCRIPTION

         EXTERIOR

         Bethesda  Place II is to be a memorable  project  that  responds to the
         unique  character  of the site while  blending  and  complementing  the
         entire Bethesda Place complex.  The building's  materials,  massing and
         site plan will respond to the first phase  character but will be unique
         and  distinctive  as a  project.  The  design  concept  draws  upon the
         multiple  identities  of the  site;  High  density  urban  location,  a
         prominent  corner  site on a major  regional  thoroughfare,  the second
         phase of an urban mixed use project,  to visually and  functionally fit
         and enhance the entire complex.

         The massing of Bethesda Place II will respect the urban street edges of
         Wisconsin  Ave. and Commerce Lane while also  responding to appropriate
         pedestrian and building  proportions relating to scale. The base of the
         building  will  visually  connect to the existing  project with similar
         treatment  of the first two  levels.  Deeply  recessed  glass and metal
         curtain  walls  between  column  pilasters  that end  with a  prominent
         cornice at the third floor line  provides an intimate  scale for retail
         and  pedestrian  activity.  The 3rd - 11th floors form the main body of
         the building with the street edge sides (east and south sides) matching
         and holding the street edges.

         A signature unifying element which provides a dominant focus and unique
         identity to the building will be found in the glass curtain wall of the
         corner shaft as it extends  through the building and ends at the top of
         the penthouse.  This ellipsoid  shaped element recalls the central mass
         and  penthouse  element of  Bethesda  Place I while  responding  to the
         unique character of this building and site.

         The plaza side (northwest  elevation) has a fenestration similar to the
         other sides but the massing  responds to the plaza with a diagonal face
         that fronts this  prominent  urban space.  The top two floors step back
         and  present a glass  curtain  wall that bows  toward the  plaza.  This
         diagonal  side also reveals the leading  edge of the central  ellipsoid
         mass  as it  penetrates  the  building  and  continues  to  end  at the
         penthouse roof.

         A  pedestrian  oriented  Streetscape  will be designed to adhere to the
         Bethesda  Central  Business  District  Sector Plan with a 20'  sidewalk
         setback at Wisconsin Avenue and will include lighting standards,  brick
         pavers and trees  along both  street  fronts  consistent  to the sector
         plan.  The  main  lobby  entrance  will  be  prominently  visible  from
         Wisconsin Ave, and will be oriented toward the corner of the two roads,
         A landscaped pedestrian connection is provided

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         between  Wisconsin  Avenue and Commerce Lane  to the existing  interior
         plaza.  The passage  will feature  landscape  planting as well as paved
         hardscape plaza material.

         The exterior  building  materials will be a mixture of revealed exposed
         granite   aggregate  precast  concrete  panels  on  the  spandrels  and
         pilasters  and pewter  colored  high  performance  glass as  continuous
         ribbon  windows and as curtain wall at the central  ellipsoid  mass and
         two story base. Anodized aluminum will be used at the window frames and
         as panels in selected  locations.  The color  palate will be similar to
         the original  Bethesda Place.  The precast concrete will have a variety
         of  textures  and colors  similar to the  rose/gray  tones of the first
         phase.

         INTERIOR

         Bethesda Place II will continue the high level of quality of design and
         finishes  found in the phase I project.  The main  entry  lobby will be
         entered  through  all glass  doors into a two story high  granite  clad
         feature lobby enclosed by a two story curtain wall. An emphasis on easy
         accessibility  and high  visibility  from  Wisconsin  Ave.  will be the
         primary objective.  A second story balcony will overlook the main floor
         and connect to the second level office spaces.

         The typical  elevator  lobbies above the second floor shall be finished
         to a base  building  standard  as  described  in  Section  II B of this
         document.

         D.       OFFICE TOWER GENERAL SPECIFICATIONS

                  Note: All values are approximate, and subject to refinements.

<TABLE>
<S>                                                                             <C>
                  Overall length (tower}                                        153'- 6"
                  Overall width (tower)                                         153'- 6"
                  Overall height (plaza floor slab to roof)                     143'- 0"
                  Typical slab to stab             (floors 2-11 )               12'- 6'
                                                   (plaza)                      14'- 0"
                  Typical slab to finish ceiling   (floors 2-11)                8'- 6"
                                                   (plaza)                      10'- 0"
                  Typical window sill height at curtain wall                    2'- 8"
                  Typical column spacing                                        20'- 0" x 40'-0" to 45'-0"
                  Typical vertical mullion spacing on curtain wall              5'- 0" o.c.
</TABLE>

         E.       LOADING DOCK SPECIFICATIONS

<TABLE>
<S>                                                                             <C>
                  Truck dock spaces (including trash bay)                       2
                  Maximum truck length                                          55'-0"
                  Height clearance                                              13'- 8" min.
                  Weight maximum                                                Standard 18 wheel
</TABLE>

         F.       VERTICAL TRANSPORTATION

         Five  passenger  elevators  grouped in two banks service the main lobby
         level  through to the 11th floor with one of five  elevators  extending
         down to service the P1 level and providing a swing freight  function as
         well. A separate bank of two parking garage access hydraulic  elevators
         service the main lobby level  through the P5 level.  The  following are
         the elevator specifications:

         Note: All Dimensions and values are approximate, and may vary depending
         upon final manufacturer and finishes selected.

             Tower Elevators (geared traction):

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                Total Quantity:                5

                Four of five (4 of 5):
                Number of floor stops          11
                Floors served                  Plaza through 11
                Door opening                   3'-6"w x 7'-0"h center opening
                Platform size                  7'-4"w x 6'-2" d
                Cab clearance (approx.)        6'-8" w x 5'-3"d
                Cab height                     9'-0"
                Weight capacity                3,500 Lbs.
                Speed                          450 F.P.M.

                One of five (1 of 5):
                Number of floor stops          12
                Floors served                  P 1 through 11
                Door opening                   4'-0"w x 7'-O"h center opening
                Platform size                  8'-0"w x 6'-2" d
                Cab clearance (approx.)        7'-2"w x 5'-3"d
                Cab height                     9'-0"
                Weight capacity                4,000 Lbs.
                Speed                          450 F.P.M.

             Parking Garage Elevators (hydraulic):

                Quantity                       2
                Floor stops                    6
                Floors served                  P5-Plaza
                Door opening                   4'-0"w x 7'-0"h center opening
                Platform size                  7'-6"w x 6'-0" d
                Cab clearance (approx.)        6'-10"w x 5'-1"d
                Cab height                     9'-0"
                Weight capacity                3,000 Lb.
                Speed                          150F.P.M.

         Note: Cab and door dimensions must meet Montgomery  County gourney size
         requirements.

II.      CORE AND SHELL DEVELOPMENT

         A.       INTRODUCTION

         This  section is intended to describe  the scope of the  proposed  base
         building development. In addition, a general description of many of the
         building's   utilities,   services  and  proposed  amenities  has  been
         provided. The work beyond what is noted here is the sole responsibility
         of the Tenant  and will be  completed  at the  Tenant's  sole  expense.
         Additionally,  any work required to  supplement  these systems shall be
         the sole  responsibility  of the Tenant and shall be  completed  at the
         Tenant's sole expense unless  expressly agreed mutually by the Building
         Owner and Tenant.

         B.       GENERAL INTERIOR AREAS

         Typical  concrete  floor  slabs will be provided  with a smooth  trowel
         finish. All core walls and columns connected to core walls are dry-wall
         finished to a minimum of 8'- 6", taped,  sanded  smooth,  and ready for
         paint.  Exterior  column  and  perimeter  walls  will  also be  drywall
         finished land paint ready.

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         Finished  ceilings  will not be provided  for the tenant  floor  areas.
         Metal decking and fireproofed  structural  steel beams are left exposed
         in these areas  except that toilet room and other  interior  core areas
         will be finished  according to the building  color and finish scheme to
         be determined.

         Core doors will be  provided  as the  "Building  Standard"  cherry wood
         veneer in the "Building  Standard" finish as provided in Bethesda Place
         I. Hardware shall be the "Building  Standard" with a hollow metal frame
         painted  to match the  finish of the  "Building  Standard"  door  frame
         color.

         C.       PUBLIC AREAS AND CORE FINISHES

                  1.       EXTERIOR FINISH MATERIALS:
                           a.       Precast concrete:  Exposed granite aggregate
                                    panels on spandrels and columns.
                           b.       Visible  (as  op,  to  butt-glazed)  window,
                                    storefront,    and   curtain-wall   mullions
                                    finished with 0.7mil.  thick clear  anodized
                                    hard coating.
                           c.       Metal   Panels;   Kynar   XL-based   painted
                                    aluminum panels at curtain wall parapet.
                           d.       1" Insulated  vision panels - Color to match
                                    Bethesda Place I at all tenant areas;  clear
                                    at retail areas.
                           e.       Glazed  Spandrel  Panels  - Color  to  match
                                    Bethesda Place I w/ black opacifier.
                           f.       Entrance doors - Herculite type or equal.
                           g.       Exterior Pavers: To match existing plaza and
                                    sidewalk.

                  2.       MAIN BUILDING  LOBBY AND MAIN  ELEVATOR  LOBBY FINISH
                           MATERIALS;
                           a.       Main Lobby Floors:  Mud-set natural stone up
                                    to 3' x3'.
                           b.       Main Elevator Lobby Floor  Accents:  Mud-set
                                    natural stone up to 3' x3'.
                           c.       Main Lobby  Main  Elevator  Lobby  Walls and
                                    Columns:  Hand-set  natural stone,  wood and
                                    polimyx painted GWB.
                           d.       Ceilings: Gypsum Wall Board (GWB) painted w/
                                    architectural reveals.
                           e.       Handrails:  Satin bronze and clear  tempered
                                    glass.
                           f.       Doors: Cherry veneer solid core doors.

                  3.       ELEVATOR CAB FINISH MATERIALS;
                           a.       Cab walls -Quality similar to Bethesda Place
                                    I.
                           b.       Cab front returns, doors and ceiling - Satin
                                    bronze.
                           c.       Floors- carpet.
                           d.       Elevator   jambs  at  typical  tenant  floor
                                    painted, color to be selected.

                  4.       MENS AND WOMENS RESTROOM FINISHES:
                           a.       Toilet Partitions:  Painted metal partitions
                                    - ceiling hung.
                           a.       Lavatory Tops: Natural stone; type TBD.
                           b.       Floors:   Ceramic   Tile;   type  and  color
                                    TBD/Carpet in vestibule.
                           c.       Walls:  Full height  ceramic tile  w/painted
                                    GWB in vestibule; color and type TBD.

         D.       HARDWARE

         Interior Core Doors:  lever-handled  latchset with satin bronze finish,
         hinges, and door stops shall be installed on all interior doors.

         F.       STRUCTURAL SYSTEMS

                  1.       DESIGN LOADS

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                  The  structural  systems  will be  designed to meet the design
                  load  requirements of Chapter 16 of the BOCA National Building
                  Code, 1996 edition.

                  The following Design Live Loads will be utilized for floor and
                  roof.

<TABLE>
<S>                                                            <C>
                 Office Floors                                 100 Ibs./sq.ft. (including partitions)
                 Lobby and Retail Areas                        100 Ibs./sq.ft.
                 Parking Levels                                50 Ibs./sq.ft.
                 Corridors, Stairs, Elevator Lobbies           100 Ibs./sq.ft.
                 Mechanical Equipment Rooms                    125 lbs./sq.ft. (or actual equipment load,
                                                                      whichever governs)
                 Snow on Roof                                  30 Ibs./sq.ft.
                 Plaza Areas                                   100 Ibs./sq.ft.
                                                                      + landscape/hardscape Weight

                 Loading and Truck Traffic Areas               250 Ibs./sq.ft.
</TABLE>

                  The  structural  frame will be designed to resist a Basic Wind
                  Speed of 80 miles per hour,  utilizing site exposure  category
                  B.

                  2.       DESCRIPTION OF STRUCTURAL SYSTEMS

                  The  structure of the building is composite  steel framing for
                  the  superstructure  and  reinforced  concrete  frame  for the
                  substructure (plaza level and below).

                  Office Tower:

                  The superstructure,  or the office tower, utilizes exterior to
                  interior column spacings of approximately 40 feet on the south
                  and east sections of the building,  and  approximately 46 feet
                  on its northwestern section.

                  The office  floor  system  consists of 3 I/2-inch  lightweight
                  concrete  placed over a 3-inch deep  bonding-type  metal floor
                  deck,  which is in turn  supported on steel  beams,  typically
                  spaced 10 feet apart. The steel is designed to act compositely
                  with the concrete topping via shear studs field-welded through
                  the  metal  deck to the  steel  beams.  Overall  depth  of the
                  structural  floor  system  is 2'-3  1/2" in the  40-foot  span
                  areas, and 2'-7 1/2" in the 46-foot spans.

                  The  building  roof  consists of roofing and  insulation  over
                  3-inch  deep  metal  roof deck on steel  beams  spaced 10 feet
                  apart.

                  Columns are  typically  14-inch x 14-inch  steel,  wide-flange
                  type. Wind loads are resisted by several  vertical  trusses or
                  K-bracing, located within stair and elevator walls.

                  Fireproofing  of the  structural  steel  floors  and  roof  is
                  achieved via sprayed-on  cementations fibers, to be applied to
                  all structural steel surfaces,  and the underside of roof deck
                  (but not to the floor decks).

                  Plaza and Parking Levels:

                  The  substructure  of the building,  i.e. from the plaza level
                  down through the Level P6, is reinforced concrete.  Additional
                  columns are  introduced in between the office tower columns in
                  an  effort to limit the  maximum  column to column  span to 30
                  feet in any direction.

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                  The floor  slabs of the parking  levels and the plaza  (ground
                  floor) level of the building  will be 8 to 9 inch thick,  with
                  thickened drop panels at columns.  Top reinforcing bars in the
                  entire P1 parking deck and the drive  aisles of parking  decks
                  P2 through P5, will be  epoxy-coated.  Concrete  columns under
                  the tower  columns will be 24-inch wide,  while  supplementary
                  columns  will be 16-inch  wide,  rectangular  in shape.  Where
                  office tower columns are located over driveways and ramps, the
                  columns  in  question  will be  terminated  and  supported  on
                  reinforced concrete "transfer" girders at the plaza level.

                  Concrete   shear  walls  will  be  utilized  under  the  steel
                  K-bracing of the office tower.

                  Slabs-on-Grade  at the P-5 & P-6 level  will be 5-inch  thick,
                  reinforced  with wire  mesh,  and placed  over vapor  barrier,
                  gravel bed, and subdrainage system.

                  Basement  walls will be  12-inch  thick  reinforced  concrete.
                  Foundations  are  expected  to be  individual  footings  under
                  columns, and continuous footings under walls.

                  Column Transition Detail:

                  Where the steel  columns of the office tower  terminate at the
                  plaza  level,  the  steel  column  base  plate  and  anchorage
                  assembly will be concealed  within a floor recess at the plaza
                  level slab at that location, as well as by the column cover.

                  3.       OUTLINE STRUCTURAL SPECIFICATIONS

                  CONCRETE WORK:

                  Concrete design and detailing will conform to the requirements
                  of the American Concrete Institute, ACl 318-95.

                  Concrete  utilized in  composite  steel  construction  will be
                  lightweight  structural  concrete ( 118 pcf density) All other
                  concrete will be normal weight.

                  Minimum ultimate  compressive  strength of concrete at 28 days
                  will be as follows:

<TABLE>
<S>                                                                    <C>
                           Concrete over Metal Deck                    3,000 psi
                           Formed Slabs and Beams                      4,000 psi
                           Columns                                     5,000 psi / 6,000 psi
                           Basement Walls                              4,000 psi
                           Footings                                    3,000 psi
                           Slabs-on-Grade                              4,000 psi
</TABLE>

                  All  concrete  exposed  to  weather  will  be   air-entrained.
                  Water-cement  ratio of  concrete  for  parking  decks  will be
                  limited to 0.40.  Reinforcing  bars will conform to ASTM A615,
                  Grade 60.

                  STRUCTURAL STEEL:

                  Structural  steel design and  detailing  shall  conform to the
                  requirements of the American Institute of Steel  Construction.
                  Structural  steel shall conform to ASTM A572, Grade 50 or ASTM
                  A36,  as noted on the plans.  Connections  between  structural
                  steel  components  will be bolted,  welded or a combination of
                  the two. Shear  connectors will be 3/4-inch  diameter x 5-inch
                  long,  field  welded to the beam  flanges  after metal deck is
                  installed.  Openings  through  steel  beams  for duct work and
                  pipes shall be

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                  permitted  only  where  specifically   called  for  on  plans.
                  Composite steel beams will be unshared.

                  METAL DECKING:

                  Metal  floor and roof deck  shall be  designed,  detailed  and
                  installed  for  conformance  to the  requirements  of the AISI
                  Specifications  for the  Design  of Light  Gage  Cold-  Formed
                  Structural  Steel  Members,  and the  Steel  Deck  Institute's
                  requirements.

                  Metal  floor  deck  shall be 3-inch  deep,  20-gauge  minimum,
                  bonding-type, phosphatized.

                  Metal  roof  deck  shall be  3-inch  deep,  22-gauge  minimum,
                  hot-dip galvanized.

         G.       MECHANICAL EQUIPMENT

<TABLE>
<S>               <C>      <C>
                  1.       MEP Design Criteria for the Heating,  Ventilating and
                           Air Conditioning (HVAC) System are as follows:

                           a.       Inside Conditions: * -+3 (degrees) F operating tolerance.
                                    Summer                                      73 (degrees) F -+3 (degrees) F/50% RH
                                    Winter                                      72 (degrees) F (No Humidity Control)

                           b.       Outdoor Conditions:
                                    Summer                                      95 (degrees) F DB
                                    Winter                                      10 (degrees) F DB

                           c.       Lighting:
                                    Office Space                                1.5 WATTS/SF (70% to Space)
                                    Main Lobby                                  5.0 WATTS/SF (100% to Space)

                           d.       Receptacles:
                                    Office Space                                2.5 WATTS/SF

                           e.       Occupancy:
                                    Office                                      7 People/1000 SF or
                                                                                1 Person/142 SF
                           f.       Outside Air:
                                    Office                                      20 CFM/Person Average
                                    Design Conditions (ASHRAE 1%)               93 (degrees) F DB/75 (degrees) F WB

                           g.       Minimum Air Circulation:                    0.65 CFM/SF

                           h.       Window Wall and Roof:

                                    1)       All Glass:

                                              The glass shall be reflective, double pane, insulating type.

                                              Shading Coefficient:

                                                     Without Interior Shading, SC = 0.25 (Maximum)

                                               U Values:         Us = 0.49 (Maximum)
                                                                 Uw = 0.42 (Maximum)

                                     2)        Spandrel:         U = 0.08 (Overall Spandrel Assembly R Value = 12.5
                                                                        Minimum)

                                     3)        Wall:             U = 0.08 (Overall Wall Assembly R Value = 12.5
                                                                        Minimum)

                                     4)        Roof:             U = 0.061 (Overall Roof Assembly R Value = 16.4
                                                                        Minimum)

                           i.       Air  Handling  Systems  for  Typical  Office
                                    Areas:

                                    1)       The  typical   floor   system  will
                                             consist of one self-contained water
                                             cooled    vertical     draw-through
                                             variable  air volume  air  handling
                                             unit (AHU) with economizer  cooling
                                             coil. Various fan
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</TABLE>

<PAGE>

                                             powered terminal devices (FPTD) and
                                             VAV boxes will be supplied  but not
                                             installed    at    a    ratio    of
                                             approximately  1 box per  1,200 SF.
                                             AHU's will have variable  speed fan
                                             drives and  replaceable  media type
                                             filters.

                                    2)       Air   will  be   supplied   through
                                             internally   lined  or   externally
                                             insulated   ductwork.   Supply  and
                                             return  ductwork will be lined near
                                             the AHU and for the  first six feet
                                             downstream of terminal  devices for
                                             acoustical     purposes,     Supply
                                             ductwork    will   be    externally
                                             insulated at other locations.

                                    3)       Supply  diffusers,  return grilles,
                                             and lay-in slot  diffusers  for the
                                             perimeter zones will be provided by
                                             the tenant within all leased areas.
                                             Supply  diffusers  for the interior
                                             zones   shall   be   two   by   two
                                             perforated face  diffusers.  Supply
                                             diffusers for elevator  lobbies and
                                             toilet  rooms will be  selected  to
                                             match    finishes    and    ceiling
                                             construction.

                                    4)       Air will be returned to the ceiling
                                             plenums  through  heat extract type
                                             light  fixtures   provided  by  the
                                             tenant.   Additional   two  by  two
                                             perforated  face return air grilles
                                             will be added to the interior  zone
                                             areas  to   supplement   the  light
                                             fixture    return    openings    as
                                             required,  and are also provided by
                                             tenant.

                                    5)       Outside  air will be  filtered  and
                                             pre-heated    through   a   heating
                                             ventilating  unit  located  at  the
                                             penthouse/roof  level.  Outside air
                                             shall  be  supplied  to each  floor
                                             through insulated supply ductwork.

                           j.       Condenser Water System:

                                    1)       The  condenser  water  system  will
                                             consist   of  a  two   cell   roof-
                                             mounted,  induced  draft  crossflow
                                             cooling tower;  two condenser water
                                             pumps.  Each cooling tower cell and
                                             pump will be sized at approximately
                                             50% of the  total  load or 360 tons
                                             per ceil.

                                    2)       The cooling  towers and main piping
                                             risers  will be sized for the total
                                             estimated  building cooling load of
                                             720 tons. Total tonnage is based on
                                             an  average  of 320 SF per  ton for
                                             209,000   SF  with  10%  added  for
                                             future capacity.

                                    3)       The  condenser  water  system  will
                                             operate  at  a  10  degrees  F  (95
                                             degrees   F  to   85   degrees   F)
                                             differential  temperature.   During
                                             the economizer  mode, the condenser
                                             water  system will supply as low as
                                             45 degrees F water to the AHU's.

                                    4)       Valved and capped  condenser  water
                                             supply  and  return  taps  will  be
                                             provided  at each floor  within the
                                             AHU room for future use.

                                    5)       Valved and capped  condenser  water
                                             supply  and  return  taps  will  be
                                             provided  within the retail spaces.
                                             The tenants  will  provide the HVAC
                                             system(s)  within the retail spaces
                                             downstream of these taps.

                           k.       Building Heat:

                                    1)       Typical office areas will be heated
                                             by electric  heating  coils located
                                             in the terminal devices.

                                    2)       Building MEP  equipment  rooms will
                                             be heated by electric  unit heaters
                                             and ventilated as required.

                                    3)       Floor heating: occupied areas above
                                             unconditioned   spaces  exposed  to
                                             atmospheric  temperatures  will  be
                                             located  above  enclosed  insulated
                                             plenums  served  by  electric  unit
                                             heaters

                           l.       Energy Management and Control System:

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                                    Controls  will be of the  electronic  direct
                                    digital  control (DDC] type. The system will
                                    provide  complete  automatic  monitoring and
                                    control of HVAC system equipment.

                           m.       Ventilation and Exhaust:

                                    Toilet   exhaust   at  each  floor  will  be
                                    exhausted  through  ductwork  by means of an
                                    exhaust fan located at the penthouse  level.
                                    Relief air is included in the toilet exhaust
                                    air quantities.

                           n.       Building Air Balance:

                                    The outside air supply air volume and toilet
                                    exhaust  relief air volume  will be designed
                                    to achieve an overall  positively  pressured
                                    building to minimize infiltration.

                           o.       Smoke Control Systems:

                                    Refer to "Life Safety System" section.

                           p.       Acoustical Design:

                                    The building MEP system as  integrated  with
                                    the building  architecture  will be designed
                                    to achieve the following noise criteria (NC)
                                    levels:

                                    1)       Typical office space: NC 40

                                    2)       Areas  adjacent  to AHU  rooms  and
                                             other equipment areas: NC 45

                           q.       Delineation   between   typical  floor  base
                                    building and tenant systems:

                                    1)       HVAC:  All equipment  downstream of
                                             the  typical   floor  primary  loop
                                             ductwork will be considered  tenant
                                             systems. FPTD's and other VAV boxes
                                             will  be  provided  stacked  on the
                                             tenant floors. FPTD's and other VAV
                                             boxes  will  be  installed  by  the
                                             tenant  under the  tenant  scope of
                                             work.  All equipment  downstream of
                                             the  condenser  water  taps will be
                                             provided by the tenant.

                                    2)       Electrical:      All      equipment
                                             downstream of the panel boards will
                                             be considered tenant systems.

                                    3)       Plumbing:  All equipment downstream
                                             of  future  plumbing  taps  will be
                                             considered tenant systems.

         H.       ELECTRICAL

                  1.       Service Entrance and Main Distribution:

                           a.       The  6000  amp  electrical  service  will be
                                    supplied    through   the   utility    vault
                                    transformer(s)  located  at the first  level
                                    below grade.  Service  entrance feeders from
                                    the transformer(s)  will serve two main 3000
                                    amp switchboards  with 277/480 volt, 3 phase
                                    power.

                           b.       The main switch gear will include heavy duty
                                    switches with high capacity current limiting
                                    fuses, surge  suppression,  and ground fault
                                    protection.

                           c.       Electrical  service  to the  typical  floors
                                    will  be fed  from  the  main  building  bus
                                    riser.

                           d.       The  electrical  systems will be designed to
                                    receive  a  Underwriters   Laboratory   (UL)
                                    master label

                  2.       Typical Floor Distribution:

                           a.       Bus  plug   taps  at  each   typical   floor
                                    electrical  closet  will  serve the high and
                                    low voltage distribution components.

                           b.       Two 42 pole  277/480  volt panels will serve
                                    the   fluorescent   lighting,   fan  powered
                                    terminal  devices,  and other  high  voltage
                                    loads.

                           c.       One t 12.5  KVA  dry  type  transformer  per
                                    floor  will  feed two 42 pole  120/208  volt
                                    panels  serving  incandescent  lighting  and
                                    receptacle loads.

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                           d.       Dedicated  power risers  extending  from the
                                    main  switchgear  will serve  typical  floor
                                    AHU's and elevator equipment. This method of
                                    distribution  will help isolate  large motor
                                    loads and the  associated  "noise"  from the
                                    tenant electrical distribution systems.

                  3.       Lighting:

                           Fluorescent   and   incandescent   lighting  will  be
                           provided in "base building" areas only.  Tenant space
                           lighting will be provided by the tenant.

                  4.       Raceways:

                           All power wiring will be in conduit or EMT.

                  5.       Emergency Lighting:

                           Refer to "Life Safety System" section.

                  6.       Emergency Power:

                           Refer to "Life Safety System" section,

                  7.       Electrical  System  Capacities  Available  for Tenant
                           Use:

                           a.       Lighting 277/480V
                                    Typical office space            1.5 WATTS/SF

                           b.       Receptacles: 120/208V
                                    Typical office space            5.0 WATTS/SF

                           c.       These capacities are in addition to electric
                                    power needed for the building MEP systems.

         I.       FIRE/LIFE SAFETY

                  1.       Building Fire Control Station:

                           a.       The building  central  fire control  station
                                    will  be a  room  protected  by  a  two-hour
                                    fire-rated  occupancy  separation located at
                                    the lobby  level.  The central  fire control
                                    station shall contain:

                           b.       Addressable   multiplex   fire   alarm   and
                                    detection system including:

                                    1)       Voice alarm and signaling system.

                                    2)       Audible   fire   alarm  and  public
                                             address system.

                                    3)       Control systems.

                                    4)       Fireman's    voice    communication
                                             system.

                                    5)       Fire     detection     and    alarm
                                             annunciator panel.

                           c.       Standby   generator   status  and  auxiliary
                                    controls.

                           d.       Elevator status and position indicator.

                           e.       Public telephone.

                           f.       Status  indicators  and  controls  for  HVAC
                                    systems.

                           g.       Controls for manual  selective  operation of
                                    one 'firemans' elevator in each bank.

                  2.       Audible Fire Alarm and Public Address System:

                           Public address system  announcements and audible fire
                           alarm  signals will be initiated on a selected  floor
                           or general  alarm  basis from the main fire alarm and
                           communication   panel  by  the  fire  alarm   system,
                           building  management or the fire department.  Speaker
                           horns  will be  located  on each  floor at  stairwell
                           entrances,  in the  elevator  lobby,  and at selected
                           places throughout the core and tenant space.  Speaker
                           horns will  alert the  occupants  and give  emergency
                           evacuation instructions.

                  3.       Fireman's Voice Communication System:

                           A separate  communication  system utilizing hand-held
                           phone sets will provide two-way communication between
                           the building fire command station and

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                           remote   stations   located  at  each  level  in  the
                           stairwells,   elevator  lobbies  and  elevator  cars.
                           Hand-held phone set will also be provided at the fire
                           pump and security office.

                  4.       ADA Compliance:

                           Alarm   initiation   device   selection  and  layout,
                           including strobe and speaker horns,  will comply with
                           applicable ADA requirements.

                  5.       Fire Detection System:

                           a.       Manual Fire Alarm:

                                    A manual  fire  alarm box or "pull  station"
                                    will be located  adjacent to each entry door
                                    to stairway shafts and building exits.

                           b.       Smoke Detectors:

                                    Ionization   type   products  of  combustion
                                    detectors will be located as follows:

                                    1)       Air handling unit rooms.

                                    2)       Electrical equipment rooms.

                                    3)       Elevator equipment rooms.

                                    4)       Penthouse equipment rooms.

                                    5)       Lower level equipment rooms.

                                    6)       Fire control station.

                                    7)       Telephone equipment rooms.

                                    8)       Each elevator  lobby - one detector
                                             to   initiate    elevator    recall
                                             controls.

                                    9)       Smoke   detectors   downstream  and
                                             upstream  of  selected  supply  and
                                             exhaust fans as required by code.

                                    10)      At each duct  connection to a riser
                                             serving 2 or more floors.

                                    11)      In the  corridor at the entrance to
                                             each stairwell.

                           c.       Rate of Rise  Defectors  - one  rate of rise
                                    detector  for  each  500  sq.  ft.  wilt  be
                                    located in the standby generator room.

                           d.       Sprinkler system and fire pump flow switches
                                    with supervised valves will be provided,

                  6.       Fire Pumps:

                           There will be one  electric  motor  driven  fire pump
                           with associated  jockey pump to serve the combination
                           standpipe  sprinkler  system.  Electric power for the
                           fire pump will have automatic transfer to the standby
                           power generator.

                  7.      Fire Suppression System:

                           a.       The   facility   will   be   covered   by  a
                                    combination  automatic  sprinkler  standpipe
                                    system  throughout  the  building.  The fire
                                    suppression   system  wilt  consist  of  the
                                    following:

                                    1)       One fire pump and one jockey pump.

                                    2)       Wet    type    sprinkler     system
                                             throughout  the building with floor
                                             control  valves  connected  to  the
                                             combination   standpipes   at   all
                                             levels.     Non-freeze     dry-pipe
                                             sprinkler  systems will be provided
                                             in  areas   subject   to   freezing
                                             conditions   such  as  the   garage
                                             areas.

                                    3)       Fireman's     fire    hose    valve
                                             connections  within each  stairwell
                                             at each level.

                  8.       Smoke Control:

                           a.       Each  stairwell  will  be  pressurized  with
                                    outside  air  via  pressurization  fans  and
                                    vertical riser distribution  ducts. The fans
                                    will be activated  automatically by the fire
                                    alarm and/or smoke detection system.

                           b.       Floor  penetrations  will be filled  with UL
                                    listed fire sating material.

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                           c.       All   ducts   which   penetrate   floors  or
                                    fire-rated   partitions  will  contain  fire
                                    dampers  or  be   enclosed   in   fire-rated
                                    enclosures.

                  9.       Standby Power Generation System:

                           a.       An  engine-driven  standby  power  generator
                                    with  automatic  controls  and a  three-hour
                                    fuel supply will be provided.

                           b.       Standby generator will supply power to:

                                    1)       Audible   fire   alarm  and  public
                                             address system.

                                    2)       Fire detection system.

                                    3)       Exitway    and   other    emergency
                                             lighting.

                                    4)       Automatic  sprinkler flow detection
                                             system.

                                    5)       Fireman's     elevators     (manual
                                             selective operation of one elevator
                                             in each bank).

                                    6)       Sump pumps and sewage  ejectors (if
                                             required).

                                    7)       Fire pumps.

                                    8)       Selected   supply  and  ventilation
                                             fans.

                                    9)       Building security systems.

                                    10)      Stairwell pressurization fans.

                  10.      Elevators:

                           a.       Emergency Signage:

                                    Graphics  will be provided  in the  elevator
                                    lobbies  to show exit  paths and exit  stair
                                    door locations.

                           b.       Emergency Elevator Operation:

                                    1)       The elevator  doors on the floor of
                                             alarm wilt remain closed.

                                    2)       In the event of power failure,  all
                                             elevators  can be  returned  to the
                                             main  floor on a  manual  selective
                                             basis  (one at a time)  powered  by
                                             the standby power generator. If the
                                             designated  main  floor is under an
                                             alarm condition, the elevators will
                                             return  to a  designated  alternate
                                             floor.

                                    3)       When the  elevators  return  to the
                                             main floor, the doors will open and
                                             the elevator will shut down.

                                    4)       For fire  fighting  purposes,  each
                                             elevator  will be  capable of being
                                             operated  by  the  Fire  Department
                                             (one  in  each   bank  at  a  time)
                                             through use of a "Fireman's  Bypass
                                             Key".

                           c.       Emergency Power Pack:

                                    Each  elevator cab will be provided  with an
                                    emergency  lighting power pack with capacity
                                    for two-hour emergency operation.

         J.       PLUMBING

                  1.       Domestic Hot Water:  Electric  water  heaters will be
                           located  within  the  janitor's  closet  at  selected
                           levels of the  building.  One heater  will  typically
                           serve three floors.

                  2.       Domestic Cold Water: Two stage domestic water up-feed
                           system with pumps and hydrocumulator  tank located in
                           one of the below grade levels will be provided.

                  3.       Sanitary   Sewer:  A  complete   system  of  sanitary
                           drainage will serve each plumbing fixture.

                  4.       Storm  Sewer:  A  complete  system of roof and garage
                           drainage  will be provided to tie into site  drainage
                           system.

                  5.       Future  Capacity:  The  following  stubouts  will  be
                           provided  for future  connection  of tenant  fixtures
                           from  one  set of  connections  at the  core  and two
                           wetstacks remotely located from the core.

                           a.       4" plugged waste connection.

                           b.       2" capped vent connection.

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                           c.       1" capped cold water.

                           d.       2" plugged condensate connection.

         The Owner provides water for use in lavatories.  Additionally, domestic
         cold  water,  waste  and vent  lines  are  provided  on each  floor for
         connection  by the Tenant as part of the tenant  work as allowed by the
         lease terms and approved in writing in advance the Owner.

         K.       TELEPHONE SERVICE

                  1.       A main  telephone  equipment  room located at a level
                           below  grade  will  be  provided  for  the  telephone
                           company   service   entrance.   This   room  will  be
                           ventilated and heated or air  conditioned as required
                           by the service provider.

                  2.       Three  four-inch  conduits  will be provided from the
                           telephone   utility   connection  point  outside  the
                           building to the main telephone room.

                  3.       Three  four-inch  conduits  will be provided from the
                           main telephone room to the first level "typical" core
                           telephone closet.

                  4.       Six six-inch sleeves will be provided in the floor of
                           the typical core telephone closet.  These sleeves are
                           intended for the tenant's use.

                  5.       The typical core telephone room is sized for vertical
                           connectivity of the telephone system. It is not sized
                           to serve as an "equipment" room. All telephone,  data
                           and LAN rooms  will be located  within  the  tenant's
                           space.

         L.       DRINKING FOUNTAINS

         A drinking  fountain will be provided on each typical  floor,  near the
         toilet rooms of each typical floor.

         M.       WINDOW COVERINGS

         "Building  Standard"  mini-blinds  will  be  installed  on  ail  window
         surfaces.  The color of these  blinds  will match the  adjacent  window
         frames.

         N.       KEYING

         All keying  shall be  coordinated  through the Building  Manager.  Keys
         shall be provided  according  to the lease  terms.  A schedule for lock
         systems should be coordinated with the Building Manager well in advance
         of the actual  ordering  of lock  systems.  All keying  will be done in
         accordance to Bethesda Place I.

         O.       MAIL FACILITIES

         United States Postal Service deliveries and pickups will be made to the
         building's  mail room on the P1 Level.  Outgoing mail may be dropped in
         the mail room.

         P.       SIGNAGE

         As required to comply with all governing codes.

                          - END OF INFORMATION MANUAL -

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                                  EXHIBIT "F-2"

                        JANITORIAL SERVICE SPECIFICATIONS

                    SPECIFICATIONS FOR 7700 WISCONSIN AVENUE
                            BETHESDA, MARYLAND 20814
                            BIDS DUE by JULY 25, 1997
                              START TIME: 6:00 P.M.

I.       OFFICES AND CONFERENCE ROOMS- ( Daily 5 DAYS PERWEEK)

         a.       Carpeting and rugs (Traffic Areas) vacuumed.
         b.       Furniture and furnishing dusted.
         c.       Ashtrays emptied and wiped clean.
         d.       Empty  trash  receptacles  and  remove  to  designated  areas,
                  replace bags as needed.
         e.       Spot clean hard surface floors (spillage, tracking, etc.)
         f.       Spot  clean  walls,  doors  (around  door  handles  and switch
                  plates).
         g.       Dust telephone, damp wipe and disinfect.
         h..      Dust file cabinets and furniture.
         i.       Spot clean partitions, ledges and entrance glass.
         j.       Dust mop tile floors.
         k.       Spot clean rugs and clean carpets.
         l.       Damp wipe counter surfaces and clean sinks.
         m.       Partition glass washed daily.

II.      OFFICES AND CONFERENCE ROOMS-PERIODIC

         a.       Detail-vacuuming each week (carpeting and rugs).
         b.       Door flames, window frames and sills dusted each month.
         c.       Venetian blinds dusted quarterly.
         d.       High ledges and molding dusted each week.
         e.       Composition floors cleaned and polished each week.
         f.       Low ledges, molding and sills dusted each week.
         g.       Rugs and carpet clean annually.
         h.       Exterior lighting fixtures dusted each month.
         i.       Vacuum upholstered furniture each month.
         j.       Doors and walls dusted
         k.       Trash receptacles damp cleaned each month.

III.     LOBBIES & CORRIDORS-Daily (5 DAYS PER WEEK)

         a.       Furniture and furnishings dusted
         b.       Carpeting and rugs vacuumed.
         c.       Walls around switch plates and door handles spot cleaned.

<PAGE>

         d.       Emergency cleaning (Spillage, tracking, etc.) On hard surfaced
                  floors.
         e.       Walls spot cleaned switch plates and door handles.
         f.       Drinking fountains cleaned, sanitized and dry polished.
         g.       Cigarette urns emptied, cleaned and dry polished.
         h.       Trash receptacles  emptied,  damp cleaned and trash removed to
                  designated area.
         i.       Metal work spot cleaned and dry polished.
         j.       Entrance glass spot-cleaned.
         k.       Rugs and carpeting spot cleaned.

IV.      LOBBIES AND CORRIDORS-PERIODIC

         a.       Molding and high ledges dusted each month.
         b.       Walls and doors dusted each month.
         c.       Lighting fixtures (exterior) dusted each month.
         d.       Composition tile floors cleaned and polished each week.
         e.       Composition tile floors  stripped,  scaled and refinished each
                  year.
         f.       Carpeting cleaned annually.
         g.       Vacuum upholstered furniture each week.
         h.       Vents and diffuses dusted each week.

V.       RESTROOMS AND COMMON AREAS-Daily (5-DAYS PER WEEK)

         a.       Clean and disinfect commodes, urinals and basins.
         b.       Clean and dry. polish mirrors.
         c.       Clean and dry polish metal work.
         d.       Sweep, mop and rinse floors.
         e.       Dust and spot clean partitions.
         f.       Spot-clean doors and walls.
         g.       Dust molding and low ledges
         h.       Furniture and furnishings dusted.
         i.       Ashtrays and cigarette urns emptied and wiped clean.
         j.       Replenish expendable rest room supplies into dispensers.
         k.       Empty trash receptacles and trash removed to designated areas.

VI.      RESTROOMS AND COMMON AREAS-PERIODIC

         a.       Lighting fixtures (exterior surface) dusted each three months.
         b.       Vents and diffusers dusted each three months.
         c.       Ceramic walls washed each two months.
         d.       Metal partitions washed each six months.

<PAGE>

         e.       Scrub floors each quarter.
         f.       Carpet shampooed annually.
         g.       Lighting fixtures and ceilings dusted each week.
         h.       Metal work cleaned and polished each week.

VII.     EMPLOYEE (BREAK ROOMS)-Daily (5 DAYS PER WEEK)

         a.       Clean sinks and counter tops.
         b.       spot-clean doors and walls.
         c.       Spot-clean doors, walls and exterior surfaces of appliances.
         d.       Empty trash receptacles-replace plastic liners.
         e.       Empty ashtrays and wipe clean.
         f.       Damp clean table tops.
         g.       Dust, mop and damp mop floors.

VIII.    EMPLOYEE,(BREAK ROOMS)-PERIODIC

         a.       Doors and walls dusted each week.
         b.       Trash receptacles washed each week.
         c.       Composition floors cleaned and polished each week.
         d.       Damp clean appliances (exterior surfaces each week).
         e.       Molding and high ledges dusted each month.
         f.       Composition floors stopped, sealed and refinished as needed..

* DAY PORTER SHALL BE PROVIDED FIVE DAYS PER WEEK, EIGHT HOURS PER DAY, HOURS TO
BE SELECTED BY MANAGEMENT INCLUDED IN THE BID.

<PAGE>

                                   EXHIBIT "G"

               SCHEDULE OF BASE BUILDING PLANS AND SPECIFICATIONS

Architectural  Design Development  Progress Set dated May 13, 1998,  prepared by
Kishimoto Gordon PC, Comprised of Pages 100,400, 401-410, 501,510 & 511.

<PAGE>

                                   EXHIBIT "1"

               TITLE INSURANCE POLICY AND COMMITMENT ON PROPERTY

<PAGE>

                                   EXHIBIT "J"

                              CONSTRUCTION SCHEDULE

                       [To be attached per Section 28.C]

<PAGE>

                                   EXHIBIT "K"

                            SCHEDULE OF BASE RENTAL

                        [To be attached per Section 4.B]

<PAGE>

                                   EXHIBIT "L"

                        SCHEDULE OF INSURANCE DEDUCTIBLES

TYPE                                                 DEDUCTIBLE
----                                                 ----------

Property                                               $10,000

Boiler                                                 $10,000

General Liability                                        -0-

Excess General Liability                                 -0-

     Real Estate Managers

     Errors / Omissions                                 $10,000

<PAGE>

                                    EXHIBIT M

                                   WORK LETTER

This Work  Letter  (the "Work  Letter")  is  attached to and made a part of that
certain Office Lease  Agreement dated  _____________,  1998 (the "Lease") by and
between Bethesda Place II Limited  Partnership,  a Maryland limited  partnership
("Landlord"),  and U.S.  Generating  Company, a California  general  partnership
("Tenant") for  approximately  197,017  rentable square feet of floor space (the
"Premises") in the office building located at 7600 Wisconsin  Avenue,  Bethesda,
Maryland 20814, commonly known as Bethesda Place II (the "Building").

In order to induce  Tenant to enter into the Lease and in  consideration  of the
mutual covenants  hereinafter  contained,  Landlord and Tenant mutually agree as
follows:

1.       TERMS:  The  capitalized  terms herein shall have the same  meanings as
         ascribed  thereto  in the Lease  unless  otherwise  expressly  provided
         herein to the contrary. The provisions of this Work Letter are intended
         to supplement the Lease and are specifically  subject to the provisions
         thereof.  In the event of any conflict  between the  provisions  of the
         Lease and the  provisions of this Work Letter,  the  provisions of this
         Work Letter shall control.

2.       AUTHORIZED  REPRESENTATIVES:  Tenant  designates Sandra Penn ("Tenant's
         Agent") as the person  authorized  to initial all plans,  drawings  and
         change  orders and grant  approvals  on  Tenant's  behalf  pursuant  to
         Article  28 of the  Lease  and this Work  Letter.  Landlord  designates
         Elliot  Schnitzer  ("Landlord's  Agent")  as the person  authorized  to
         initial all plans,  drawings and change  orders and grant  approvals on
         Landlord's  behalf  pursuant  to  Article 28 of the Lease and this Work
         Letter.  Either Tenant Or Landlord  shall have the right to designate a
         new Agent at any time by written notice delivered to the other party at
         least two (2) Business Days in advance.

3.       COST OF  BASE  BUILDING  UPGRADES:  Supplementing  Section  28.A of the
         Lease, the cost to Tenant of design of the Base Building Upgrades shall
         be the amount  charged by the  architect of the Base  Building for such
         design  services,  at the hourly rate set forth in Landlord's  contract
         with such architect and approved by Tenant.  Landlord shall require all
         general  contractors  who bid on the Base  Building to include in their
         bids (i) unit  prices  for all  labor  and  materials  for  which it is
         customary  in the  construction  industry  to give  unit  prices  for a
         project of the size of the Base Building, and (ii) unit prices for each
         of a list of possible Base Building  Upgrades  supplied by Tenant.  The
         cost to Tenant of construction  of each Base Building  Upgrade shall be
         the amount charged by the applicable  Base Building  subcontractor  for
         such Base Building Upgrade (which amount, if a unit price rate is shown
         in Landlord's Contractor's bid for such Base Building Upgrade, shall be
         at such unit price rate,  and which amount  shall  include a credit for
         labor and materials,  if any, not used in the  construction of the Base
         Building as a result of the construction of such Base Building Upgrade,
         which  credit  shall be at the unit  price  rate  for  such  labor  and
         materials shown on Landlord's Contractor's bid, if unit prices for such
         labor and materials are shown on Landlord's Contractor's bid) plus fees
         to the Landlord's Contractor not to exceed (i) five percent (5%) of the
         amount  charged  by  the  subcontractor,  for  general  conditions  and
         overhead,  and (ii) five percent (5%) of the sum of the amount  charged
         by the subcontractor  and the five percent (5%) general  conditions and
         overhead,  as a  contractor's  fee.  Landlord's  Contractor  shall give
         Tenant  fixed  price bids for each Base  Building  Upgrade,  and Tenant
         shall  have the right to  negotiate  value  engineering  changes to the
         plans  for each  Base  Building  Upgrade  with  Landlord's  Contractor.
         Notwithstanding the foregoing, for any Base Building Upgrades estimated
         to cost in excess of Thirty Thousand Dollars ($30,000.00), for which it
         would be  practicable  to use a  subcontractor  other  than  Landlord's
         Contractor's subcontractor for the Base Building, Landlord's Contractor
         shall obtain bids from at least three (3) subcontractors (one of which

<PAGE>

         shall be Landlord's  Contractor's  subcontractor for the Base Building)
         and, after  analyzing  such bids,  shall deliver such bids to Landlord,
         Landlord's architect and Tenant. Tenant will then determine, subject to
         the reasonable  objection of Landlord and Landlord's  architect,  which
         bid will be accepted.  Tenant or Tenant's Agent may designate  specific
         subcontractors from whom the Landlord's  Contractor may obtain bids. No
         Base Building  Upgrade shall be constructed  at Tenant's  expense until
         Tenant has agreed in writing to the cost of such Base Building Upgrade.

4.       CHANGES AND CHANGE ORDERS:

         A.   Supplementing   Sections  28.A,   28.F  and  28.G  of  the  Lease,
         construction of the Base Building,  Base Building  Upgrades and Initial
         Leasehold Improvements shall be subject to such modifications which are
         required  (i)  to  correct   architectural  or  engineering  errors  or
         omissions,   or  to  comport   with  good  design,   engineering,   and
         construction practices,  (ii) due to field conditions,  (iii) to comply
         with applicable  laws,  regulations and codes ("Code") and/or to obtain
         or to comply with any required permit  (including,  but not limited to,
         the  construction  permits  for  the  Base  Building  and  the  Initial
         Leasehold  Improvements) (such modifications being hereinafter referred
         to as "Necessary Modifications").  In the event that any such Necessary
         Modification to Landlord's  Work (i) will materially  impact the design
         of the  Building  or the  Premises,  or (ii) will  result in a material
         change to the Initial  Leasehold  Improvements,  or (iii) will increase
         the cost of any Base Building Upgrade, alone or together with all prior
         modifications to such Base Building  Upgrade,  by more than ten percent
         (10%) of the original estimated cost of such Base Building Upgrade,  or
         (iv) will increase the cost of the Initial  Leasehold  Improvements  by
         more than Five Thousand  Dollars  ($5,000.00)  by itself,  or more than
         Twenty-five  Thousand  Dollars  ($25,000.00)  in the aggregate with all
         prior  modifications  to the  Initial  Leasehold  Improvements  (each a
         "Tenant  Impact  Change"),  Landlord  agrees to  notify  Tenant of such
         Tenant Impact  Change within three (3) Business Days after  learning of
         the same. In addition,  if there is more than one practical alternative
         for the  performance of such Tenant Impact Change,  Landlord  agrees to
         consult in good faith with Tenant  regarding the  appropriate  means of
         implementing  such Tenant Impact Change.  Landlord  agrees to implement
         any reasonable alternative solution proposed by Tenant for such change,
         to the extent that such  alternative  will not  increase the cost to be
         borne by  Landlord  or delay  the  completion  of the  Landlord's  Work
         (unless  Tenant  agrees to accept such  risks,  in which event any such
         delay shall constitute a Tenant Caused Delay),  or adversely impact the
         structure of or systems serving the Building.

         B. If Tenant  requests  any change or addition to the Base  Building or
         Base Building Upgrades,  which is not a Necessary  Modification,  after
         Tenant's approval of the Base Building Plans and Specifications,  or if
         Landlord's Contractor constructs the Initial Leasehold Improvements and
         Tenant  requests  any  change  or  addition  to the  Initial  Leasehold
         Improvements after Tenant's approval of the Leasehold Improvement Plans
         and  Specifications,  Landlord  shall not be  obligated to perform such
         change or addition,  unless  Tenant agrees in writing to accept any and
         all delays and increases in design and construction costs occasioned by
         such change or addition (it being  understood  and agreed that any such
         delays shall constitute Tenant Caused Delays).  All additional expenses
         attributable to any change order (which is not a Necessary Modification
         to the Base Building or Base Building Upgrades) requested by Tenant and
         approved by Landlord and Tenant with respect to  Landlord's  Work shall
         be deducted from the Improvement  Allowance or the Improvement Loan, if
         any (or, if the Improvement Allowance and the Improvement Loan, if any,
         are  exhausted,  shall be payable by Tenant in accordance  with Section
         28.F(4) of the Lease).

         Tenant shall submit all change order proposals to Landlord's Contractor
         on AIA Document G709. Within a reasonable time under the circumstances,
         not to

                                       2
<PAGE>

         exceed ten (10) Business  Days,  after receipt of any such change order
         proposal, Landlord shall notify Tenant in writing of the cost and delay
         associated  with  any  Tenant-requested  change  order  which  is not a
         Necessary  Modification to the Base Building or Base Building  Upgrades
         (it being  understood that the estimates  thereof  provided by Landlord
         shall be binding), and shall supply Tenant upon request with reasonable
         documentation supporting any additional expenses charged to Tenant with
         respect to change orders (which are not Necessary  Modifications to the
         Base  Building  or Base:  Building  Upgrades)  requested  by  Tenant to
         Landlord's  Work.  The cost to Tenant  for  construction  of any change
         orders (which are not Necessary  Modifications  to the Base Building or
         Base Building  Upgrades)  shall be the amount charged by the applicable
         subcontractor for construction of such change order (which amount shall
         include  a credit  for  labor and  materials,  if any,  not used in the
         construction  of the Building as a result of the  construction  of such
         change  order,  which  credit  shall be at the unit price rate for such
         labor and  materials  shown on  Landlord's  Contractor's  bid,  if unit
         prices  for  such  labor  and   materials   are  shown  on   Landlord's
         Contractor's bid) plus fees to the Landlord's  Contractor not to exceed
         (i) five percent (5%) of the amount charged by the  subcontractor,  for
         general conditions and overhead,  and (ii) five percent (5%) of the sum
         of the amount  charged by the  subcontractor  and the five percent (5%)
         general  conditions  and overhead,  as a contractor's  fee.  Landlord's
         Contractor  shall give Tenant  fixed price bids for each change  order,
         and Tenant shall have the right to negotiate value engineering  changes
         to  the  plans  for  each  change  order  with  Landlord's  Contractor.
         Notwithstanding the foregoing, for any change order the construction of
         which  is  estimated  to cost in  excess  of  Thirty  Thousand  Dollars
         ($30,000.00),  for which it would be practicable to use a subcontractor
         other than Landlord's Contractor's subcontractor, Landlord's Contractor
         shall obtain bids from at least three (3) subcontractors  (one of which
         shall be Landlord's  Contractor's  subcontractor)  and, after analyzing
         such bids,  shall deliver such bids to Landlord,  Landlord's  architect
         and  Tenant.  Tenant  will then  determine,  subject to the  reasonable
         objection  of  Landlord  and  Landlord's  architect,  which bid will be
         accepted.   Tenant   or   Tenant's   Agent   may   designate   specific
         subcontractors from whom the Landlord's  Contractor may obtain bids. In
         no event shall any change order for the Base  Building or Base Building
         Upgrades, which is a Necessary Modification, be implemented at Tenant's
         expense,  nor shall the delay  occasioned  by any change  order for the
         Base  Building  or  Base  Building  Upgrades,   which  is  a  Necessary
         Modification,  be a Tenant Caused Delay,  except as otherwise set forth
         in Paragraph 4.A with respect to Tenant Impact Changes.

         C. All change orders shall be in writing in substantially the same form
         as the AIA standard  change order form (AIA Document  G701),  and shall
         identify  any  change  in  the  cost  or  time  for  completion  of the
         Landlord's  Work which is  attributable to such change order. No change
         order  chargeable to Tenant under this Paragraph 4 shall be implemented
         unless and until  Tenant  shall agree in writing to such change  order,
         the cost  thereof  and the  amount of Tenant  Caused  Delay  occasioned
         thereby.

         D. Tenant and Tenant's  Architect shall have the right to rely upon the
         Base Building Plans and  Specifications (i) being free of architectural
         and engineering errors and omissions,  (ii) comporting with the design,
         engineering and  construction  practices  prevailing in the Washington,
         D.C.  area,  and (iii)  complying  with Code and any  required  permits
         (collectively,  being  "Accurate").  If  Tenant  incurs  any  costs  in
         connection   with  the   preparation   or  revision  of  the  Leasehold
         Improvement  Plans and  Specifications  or the construction of Tenant's
         Work  as a  result  of  a  failure  of  the  Base  Building  Plans  and
         Specifications,  in any respect,  to be Accurate,  then Landlord  shall
         reimburse  Tenant for any such  reasonable and documented  costs within
         fifteen (15) days after  Tenant's  submission to Landlord of an invoice
         therefor.  If Tenant is delayed in the completion of Tenant's Work as a
         result of a failure of the Base Building Plans and  Specifications,  in
         any  respect,  to be  Accurate,  then the time  allotted to Tenant,  in
         Section 1.A (4) of the Lease,

                                       3
<PAGE>

         for the completion of Tenant's Work shall be increased by the number of
         days  of  such  delay.  In no  event  shall  any  delay  in  design  or
         construction,  which arises from a failure of the Base  Building  Plans
         and  Specifications  to be Accurate in any respect,  be a Tenant Caused
         Delay.  Tenant agrees to give Landlord written notice of any failure of
         the Base Building  Plans and  Specifications  to be Accurate as soon as
         reasonably practicable after Tenant's discovery of such failure. Tenant
         further  agrees to use  reasonable  efforts  to  mitigate  its  damages
         arising from any failure of the Base Building Plans and  Specifications
         to be Accurate.

5.       BIDDING PROCESS FOR INITIAL LEASEHOLD IMPROVEMENTS:

         Supplementing  Section  28.F of the Lease,  the bid  packages  that are
         delivered  to the  general  contractors  who are  invited to bid on the
         Initial Leasehold  Improvements  shall contain a fixed deadline for the
         completion of the Initial Leasehold Improvements.  Such contractors may
         be  asked  for a lump sum bid or for a  guaranteed  maximum  price,  at
         Tenant's option.

         Tenant shall have the right to negotiate value  engineering  changes to
         the Leasehold  Improvement  Plans and  Specifications  with the general
         contractor it selects to construct the Initial Leasehold  Improvements.
         The  Construction  Schedule  will give  Tenant  thirty  (30) days after
         receipt of the bids  within  which to submit to Landlord in writing any
         requests for  approval of value  engineering  changes to the  Leasehold
         Improvement  Plans  and  Specifications.  Landlord's  approval  of such
         changes shall not be unreasonably withheld, conditioned or delayed.

         Landlord  and Tenant  shall  require  that each  contractor  bidding to
         perform the Initial  Leasehold  Improvements to identify and deliver to
         Landlord and Tenant a list of any "long lead time" items of the Initial
         Leasehold  Improvements,  as well as any reasonable  non-long lead time
         substitutes  therefor which are routinely designated by such bidder. No
         item of the Initial Leasehold  Improvements shall be considered a "long
         lead time" item under the Lease unless designated as such in connection
         with the bidding of the Initial Leasehold Improvements as aforesaid (or
         in the case of a change order  chargeable to Tenant under  Paragraph 4,
         designated  as a "long  lead  time"  item at or  prior  to the time the
         change order is approved by Tenant).

6.       INSPECTIONS:  The  architect  retained  by Tenant to design the Initial
         Leasehold Improvements ("Tenant's Architect"), Tenant's Agent and other
         representatives  of Tenant shall have the right,  from time to time, to
         observe the progress of Landlord's  Work, to inspect  Landlord's  Work,
         and to reject  any  Landlord's  Work not in  conformance  with the Base
         Building Plans and  Specifications  or Leasehold  Improvement Plans and
         Specifications,  as  applicable;  however,  no such  observation  shall
         create  liability  or  responsibility  on the part of the  Tenant  with
         respect to the nature or quality of Landlord's Work.  Landlord shall be
         available, and cause Landlord's Contractor to be available, to Tenant's
         Architect,  Agent and/or other  representatives  from time to time upon
         reasonable  prior notice when necessary or desirable for the purpose of
         reviewing  Landlord's  Work.  Landlord shall keep Tenant informed as to
         all material  governmental  inspections  of  Landlord's  Work and shall
         permit Tenant's  Architect,  Agent and/or other  representatives  to be
         present thereat.

7.       CORRECTION OF WORK:  Landlord's  Contractor  shall promptly correct any
         item of  Landlord's  Work  rejected  by  Tenant's  Architect  or  other
         authorized representative for failing to conform to the requirements of
         the Base Building Plans and Specifications or the Leasehold Improvement
         Plans and  Specifications,  as  applicable,  to the extent such item of
         Landlord's   Work  in  fact   fails  to   conform  to  such  plans  and
         specifications. Upon completion of correction of any such rejected item
         of Landlord's Work,  Landlord's  contractor shall arrange with Tenant's
         Architect or other authorized representative to reinspect such item.

                                       4
<PAGE>

8.       PROGRESS  MEETINGS:   Landlord's  Agent,  Tenant's  Agent,   Landlord's
         Contractor  and Tenant's  Contractor,  if any,  will  conduct  progress
         meetings during the  construction  process.  Until the  commencement of
         construction  of the  Initial  Leasehold  Improvements,  such  progress
         meetings shall be held, at least once every two weeks, at the office of
         Landlord's  Contractor.  Throughout the period during which the Initial
         Leasehold  Improvements are being  constructed,  such progress meetings
         shall  be  held  weekly  at  the  office  of  the  general   contractor
         constructing the Initial Leasehold improvements  (Landlord's Contractor
         or Tenant's  Contractor,  as applicable).  Tenant's  Architect shall be
         given reasonable prior notice of, and shall be entitled to attend,  all
         such progress meetings.

9.       CONSTRUCTION  SCHEDULE  REVISIONS.  Landlord shall promptly  deliver to
         Tenant all revisions of the Construction Schedule.

10.      TENANT'S RIGHT TO WORK COST INFORMATION:

         A. The cost of the Base Building Upgrades and, if Landlord's Contractor
         constructs the Initial Leasehold Improvements,  the cost of the Initial
         Leasehold  Improvements  are sometimes  hereinafter  referred to as the
         "Work  Costs".  Landlord  shall  submit to Tenant  monthly  during  the
         performance of Landlord's Work a report setting forth in detail:

         i.       A  computation  of the total  Work Costs  incurred  during the
                  prior month (including all change orders  chargeable to Tenant
                  under Paragraph 4 hereof); and

         ii.      The  cumulative  Work Costs  incurred  through the end of such
                  month.

         Such report  shall be  submitted  by the  twentieth  (20th) day of each
         month and, until Tenant is obligated to make Progress Payments pursuant
         to Section  28.F(4) of the Lease,  shall be accompanied by AIA Document
         G702,  certified  by  Landlord  that  all  Work  Costs  due  Landlord's
         Contractor  and  subcontractors  have been duly paid, and by final lien
         waivers from all  subcontractors  with  subcontracts in excess of Fifty
         Thousand   Dollars   ($50,000.00),   who  have  fully  performed  their
         respective subcontracts.

         When (and if) Tenant is obligated to make Progress Payments pursuant to
         Section  28.F(4) of the Lease,  said  report  shall  accompany  each of
         Landlord's monthly invoices to Tenant for Progress  Payments,  and such
         invoices shall also be  accompanied by AIA Document G702,  certified by
         Landlord   that  all  Work   Costs  due   Landlord's   Contractor   and
         subcontractors  for work covered by the last monthly  Progress  Payment
         invoice (if any) have been duly paid,  and by final lien  waivers  from
         all  subcontractors  with  subcontracts  in  excess  of Fifty  Thousand
         Dollars  ($50,000.00),   who  have  fully  performed  their  respective
         subcontracts.

         B. All Work Costs and the portion (if any) thereof to be paid by Tenant
         shall be subject to audit, verification,  and correction, if necessary,
         by Tenant and/or its authorized  representatives (who shall have access
         to the relevant  portions of the Landlord's  books and records for such
         purpose) without either party being prejudiced by any payment thereof.

11.      COORDINATION OF LANDLORD'S WORK AND TENANT'S WORK:

         A.  Supplementing  Section 28.G of the Lease,  if Tenant elects to have
         the Initial Leasehold Improvements  constructed by Tenant's Contractor,
         then for at least  fifteen (15) days before  substantial  completion of
         the Base  Building  and Base  Building  Upgrades  for any  floor of the
         Building,  Tenant's  Contractor shall be given access to such floor for
         the purpose of constructing  Initial Leasehold  Improvements,  provided
         that (i) Tenant's  Contractor  shall  coordinate  any  construction  it
         performs on such floor with Landlord's Contractor, (ii) Tenant's

                                       5
<PAGE>

         Contractor's  construction  shall not  unreasonably  impede,  hinder or
         delay  Landlord's  completion of the Base Building or the Base Building
         Upgrades,  (iii) Tenant shall maintain the liability insurance coverage
         required  by this  Lease,  and (iv)  Tenant  shall  indemnify  Landlord
         against any and all  damages  sustained  in  connection  with  Tenant's
         Contractor's  construction  work,  unless  such damage is caused by the
         negligence or willful misconduct of Landlord, its agents,  employees or
         contractors. Landlord shall require Landlord's Contractor to Coordinate
         with  Tenant's  Contractor  so  as to  permit  Tenant's  Contractor  to
         commence construction of the Initial Leasehold  Improvements on a floor
         as soon as reasonably  practicable  prior to substantial  completion of
         the Base  Building and Base  Building  Upgrades  for such floor.  After
         substantial  completion of the Base Building and Base Building Upgrades
         on  such  floor,   (i)  Landlord's   Contractor  shall  coordinate  any
         construction it performs on such floor with Tenant's  Contractor,  (ii)
         Landlord's  Contractor's  construction  shall not unreasonably  impede,
         hinder  or  delay  Tenant's  Contractor's  completion  of  the  Initial
         Leasehold  Improvements,  and (iii)  Landlord  shall  indemnify  Tenant
         against any and all damages  sustained in  connection  with  Landlord's
         Contractor's  construction  work,  unless  such damage is caused by the
         negligence or willful  misconduct of Tenant,  its agents,  employees or
         contractors.

         B.  Supplementing  Sections  23.F(3) and 28.G of the Lease,  during any
         period when Landlord's  Contractor and  contractors  employed by Tenant
         are  both  working  on a  floor  of the  Premises,  and  Tenant  or its
         contractors  are  required  to  coordinate  their work with  Landlord's
         Contractor,   Landlord   shall  require   Landlord's   Contractor   and
         subcontractors  to cooperate  with Tenant's  contractors to provide for
         the safe storage in the Building of the Tenant's building equipment for
         such floor.

12.      PERMITS AND  INSPECTIONS:  Landlord  shall  maintain for  inspection by
         Tenant copies of all approvals,  permits, inspection reports, and other
         governmental  consents required of Landlord or Landlord's Contractor in
         connection with Landlord's  Work.  Tenant shall maintain for inspection
         by Landlord copies of all approvals,  permits,  inspection reports, and
         other governmental  consents required of Tenant or Tenant's  Contractor
         in connection  with Tenant's  Work.  Each party will cooperate with the
         other in obtaining any necessary  approvals,  permits,  inspections  or
         other governmental consents.

13.      ENVIRONMENTAL CERTIFICATIONS:  The contracts for the general contractor
         for the Base  Building and Base  Building  Upgrades and for the Initial
         Leasehold Improvements shall obligate the Landlord's Contractor and the
         Tenant's   Contractor,   if  any,  to  provide  written   environmental
         certifications  to Landlord and Tenant,  substantially  in the form set
         forth as Exhibit "M-2",  within thirty (30) days after the Commencement
         Date.

14.      TENANT CAUSED DELAYS:  Notwithstanding  anything to the contrary in the
         Lease or in this Work Letter, no Tenant Caused Delay shall be deemed to
         have occurred  unless  Landlord  gives Tenant prior  written  notice or
         written notice within ten (10) days of Landlord's  receipt of notice of
         the  occurrence,  specifying the claimed reasons for such Tenant Caused
         Delay.  There shall be  excluded  from the number of days of any Tenant
         Caused Delay the period from the beginning date of any claimed delay to
         the date on which Landlord's  notice is given to Tenant, as well as any
         days of delay  which are  primarily  caused by any act or  omission  of
         Landlord, its agents, or contractors. No event shall be deemed a Tenant
         Caused  Delay  which  does  not,  in  fact,  delay  the  completion  of
         construction.

15.      PUNCH LISTS:

         A.  If   Tenant's   Contractor   constructs   the   Initial   Leasehold
         Improvements,  then on or within five (5) Business Days after  Landlord
         delivers each floor of the

                                       6
<PAGE>

         Premises  to Tenant  with all Base  Building  items  and Base  Building
         Upgrades  substantially  complete,  Landlord  and  Tenant  shall make a
         preliminary  walkthrough  inspection  of such floor and prepare a punch
         list  of  defective  and  incomplete   work  requiring   correction  or
         completion  by Landlord.  Any disputes as to the nature or existence of
         any punch list item shall be resolved by the  Arbitrator  described  in
         Paragraph 17 hereof.  Subject to Force Majeure,  Landlord shall correct
         or complete all items on such punch list within  thirty (30) days after
         delivering such floor to Tenant.

         B.  If  Landlord's   Contractor   constructs   the  Initial   Leasehold
         Improvements,  then on or within five (5) Business  Days after the date
         the Lease Term  commences for each floor of the Premises,  Landlord and
         Tenant shall make a preliminary  walk-through  inspection of such floor
         and prepare a punch list of defective  and  incomplete  work  requiring
         correction or completion by Landlord.  Any disputes as to the nature or
         existence  of any punch list item shall be resolved  by the  Arbitrator
         described in Paragraph 17 hereof.  Subject to Force  Majeure,  Landlord
         shall  correct or complete  all items on such punch list within  thirty
         (30) days after the date the Lease Term commences for such floor.

16.      LANDLORD'S  WARRANTY:  In addition  to (and not in lieu of)  Landlord's
         obligations under the Lease with respect to repairs,  Landlord warrants
         to Tenant that Landlord's Work will be free from defects in workmanship
         and materials for a period of one (1) year from the Commencement  Date.
         Therefore,  if prior to the first anniversary of the Commencement Date,
         Tenant  shall  reasonably  determine  that  any of the  workmanship  or
         material used in Landlord's Work is defective,  and Tenant shall, prior
         to such first anniversary of the Commencement Date, notify the Landlord
         in writing that such  workmanship  or material is  defective,  Landlord
         shall cause such defective  workmanship or material to be appropriately
         corrected,  repaired or  replaced,  without  cost or expense to Tenant.
         Such correction,  repair, or replacement shall be performed as promptly
         as  practical  and in such manner so as to minimize  interference  with
         Tenant's business operations in the Premises.

17.      DISPUTE  RESOLUTION:  Except as otherwise set forth herein, any dispute
         between the parties arising out of the construction,  interpretation or
         performance  of  Article 28 of the Lease or this Work  Letter  shall be
         resolved exclusively by ________________ (the "Arbitrator"),  who shall
         as  promptly  as  possible  make a  determination  as to the matters in
         dispute.  The time and place of all meetings  and hearings  relating to
         the dispute resolution shall be mutually convenient to the parties, who
         shall each be given  reasonable  advance  notice  thereof.  The parties
         shall each be entitled to present  evidence  to the  Arbitrator,  whose
         opinion shall be final and binding. The determination of the Arbitrator
         shall be given in writing and signed by the Arbitrator and a copy shall
         be given to each party.

79063002.23E

                                       7
<PAGE>

                                   EXHIBIT M-2

                FORM OF CONTRACTOR'S ENVIRONMENTAL CERTIFICATION

         In the  construction  of the building known as 7600  Wisconsin  Avenue,
Bethesda,   Maryland  (the   "Building"),   the   undersigned   contractor  (the
"Contractor")  and its  subcontractors  and materialmen did not, in violation of
any Environmental Law (defined below), place in the Building or on the land upon
which it is built (the "Land") any Hazardous  Materials  (as defined  below) and
did  not  use  the  Building  or  the  Land  for  the  manufacture,  generation,
processing,  treatment,  storage or disposal  of any  Hazardous  Materials;  the
Contractor  has not received  notice and has no reason to anticipate the receipt
of (i) notice of any pending claim, or threatened  action or proceeding (and the
Building and/or the Contractor is/are not subject to any environmentally related
consent order or other judicial  order or mandate)  relating to the condition of
the  Building,  or (ii)  any  alleged  violation  of  federal,  state  or  local
environmental,  health or safety statute, ordinance or regulation, including, by
way of example and not of limitation,  the Comprehensive  Environmental Response
Compensation and Liability Act ("Superfund" or "CERCLA"),  42 U.S.C.  Subsection
9601 et seq., the Superfund Amendments and Reauthorization Act of 1986 ("SARA"),
42 U.S.C.  Subsection 9601 (20)(D),  the Resource  Conservation and Recovery Act
(the "Solid Waste Disposal Act" or "RCRA"),  42 U.S.C.  Subsection 6901 et seq.,
the Federal  Water  Pollution  Control Act, as amended by the Clean Water Act of
1977  ("CWA"),  33  U.S.C.  Subsection  1251 et seq.,  the Clean Air Act of 1966
("CAA"), as amended, 42 U.S.C. Subsection 7401 et seq., the Federal Insecticide,
Fungicide and  Rodenticide Act ("FIFRA"),  7 U.S.C.  Subsection 136 et seq., the
Occupational Safety and Health Act ("OSHA"),  29 U.S.C.  Subsection 651 et seq.,
the Safe Drinking  Water Act ("SDWA"),  42 U.S.C.  Subsection  399f et seq., the
Toxic Substances  Control Act ("TSCA"),  15 U.S.C.  Subsection 2601 et seq., and
any  and all  state,  county  and  local  environmental  laws,  regulations  and
ordinances (collectively, the "Environmental Laws"). To the best of Contractor's
knowledge,   the  Building  and  the  Contractor  are  in  compliance  with  the
Environmental  Laws,   including  all  reporting,   licensing,   permitting  and
registration  requirements  imposed or otherwise  required by the  Environmental
Laws. As used herein,  the term "Hazardous  Material" shall include (i) asbestos
or asbestos containing materials,  whether or not friable and whether or not the
asbestos or asbestos  containing  materials are encapsulated or otherwise deemed
not  to  constitute  a  present   health  hazard  if  left   undisturbed;   (ii)
ureaformaldehyde foam insulation; (iii) petroleum,  petroleum distillates,  oil,
or petroleum products and their by-products;  (iv) any lead-based paint; (v) any
electrical  transformers,  transducers,  capacitors or other similar  electrical
transmission  equipment  containing  dielectric fluids with detectible levels of
polychlorinated or polybrominated  biphenyls ("PCBs" and "PBBs,"  respectively);
(vi) leaded solders or fluxes, lead-containing plumbing fixtures, drinking water
coolers,  piping  and  conduits;  or  (vii)  any  substance  or  combination  of
substances defined as "hazardous  substances,"  "hazardous  wastes,"  "extremely
hazardous  waste,"  "hazardous  materials,"  "toxic  substances,"  or any  other
category  of  similar  import  in  any   Environmental  Law  or  any  regulation
promulgated  pursuant  thereto,  and  any  containers  currently  or  previously
containing the same.

                                      CONTRACTOR:

                                      ________________________________

                                       By:_____________________________

                                       8
<PAGE>

                                    EXHIBIT B

                        FLOOR PLAN OF SUBLEASED PREMISES

                                  [WHEREAS #2]

                                [GRAPHIC OMITTED]

<PAGE>

                                [GRAPHIC OMITTED]

<PAGE>

                                    EXHIBIT C

                               COMMENCEMENT LETTER

                                [Paragraph 1 (B)]

Date:      __________________________________

Subtenant: __________________________________

Address:   __________________________________

                  Re:      Commencement  Letter  with  respect  to that  certain
                           Sublease dated __________________ by and between PG&E
                           GENERATING  COMPANY,  as  Sublandlord,  and INFORMAX,
                           INC.,  as  Subtenant,  for  premises in the  Building
                           located at 7600 Wisconsin Avenue, Bethesda, Maryland.

Dear __________________:

         In accordance  with the terms and  conditions  of the above  referenced
Lease, Tenant hereby accepts possession of the Premises and agrees as follows:

         1. The Rent Commencement Date of the Sublease is __________________;

         2. The Termination Date of the Sublease is _____________________.

         3. The rentable area of the Subleased Premises is ________ square feet.

         4. The Base Rental is $_________ per year.

         5. Subtenant's Share is ________%.

         Please  acknowledge  your acceptance of possession and agreement to the
terms set forth  above by  signing  all  three (3)  copies of this  Commencement
Letter in the space provided and returning two (2) fully executed  copies of the
same to my attention.

                                       Sincerely,
                                       PG&E GENERATING COMPANY

                                       By: __________________________

Agreed and Accepted:

Tenant: _______________________________

By:     _______________________________

Name:   _______________________________

Title:  _______________________________

Date:   _______________________________

<PAGE>

                                    EXHIBIT D

                           BASE BUILDING IMPROVEMENTS

                                [Paragraph 2(a)]

                               BETHESDA PLACE II
                             7600 WISCONSIN AVENUE
                  BASE BUILDING - SUB-TENANT WORK DELINEATION

<TABLE>
<CAPTION>
DESCRIPTION                                                          BASE BUILDING     SUB-TENANT
-----------                                                          -------------     ----------
<S>                                                                     <C>              <C>
ARCHITECTURAL
Concrete Floor in Tenant Area                                              x
Concrete Floors in Mech./Elec./Tel./Jan.                                   x
Gypsum Board Partitions or Surfaces (taped and spackled
   suitable for paint finishes)
      - Perimeter (Including Columns)                                      x
      - Columns (interior)                                                                  x
      - Core                                                               x
Toilet Rooms (all finishes)                                                x
MEP Rooms (all finishes)                                                   x
Exit Stairs (all finishes)                                                 x
Janitor Closets (all finishes)                                             x
Main Lobbies (all finishes)                                                x
Security/Concierge desks                                                   x
Typical elevator lobby finishes, Floor (6-11)
      - Single Tenant Floors                                                                x
Painting/Wallcoverings in Tenant Areas                                                      x
Ceiling System
      - Toilet Rooms                                                       x
      - Tenant Area                                                                         x
      - MEP Rooms                                                          N/A
      - Janitor Closets                                                    N/A
      - Elevator Lobby - Single Tenant Floor                                                x
Floor Covering w/base
      - Tenant Area                                                                         x
      - Elevator Lobby - Single Tenant Floor                                                x
Window Blinds                                                              x
Doors & Hardware
      - Core                                                               x
      - Tenant Area                                                                         x
Mullion Adapters                                                                            x
ADA Code Requirements
      - Parking Garage                                                     x
      - Site                                                               x
      - Building Entries                                                   x
      - Main Lobby                                                         x
      - Elevators                                                          x
      - Exit Stairs                                                        x
      - Toilet Rooms - core areas only                                     x
      - Tenant Area                                                                         x
Exterior Signage
      - Directional Site Signage                                                            x
      - Exterior Signage/Retail                                                             x

<FN>
                                                                      x - Sub-Tenant Standards
</FN>

<PAGE>
<CAPTION>
DESCRIPTION                                                          BASE BUILDING     SUB-TENANT
-----------                                                          -------------     ----------
<S>                                                                     <C>              <C>
Interior Signage
      - Building Directories                                               x
      - Core Areas                                                         x
      - Tenant Areas                                                                        x
STRUCTURAL
Loading Capacity (per code/base building specifications)                   x
Additional Loading Capacity                                                                 x
ELECTRICAL
Incoming Service                    Amps Total                             x
Switchgear                                                                 x
Distribution to Closets                                                    x
      - Low Voltage Power Panels                                           x
      - High Voltage Lighting Panels                                       x
      - Transformers                                                       x
Emergency Lighting
      - Core Area                                                          x
      - Tenant Area     psf                                                                 x
Light Fixtures
      - Core Area                                                          x
      - Tenant Area    psf                                                                  x
      - Elevator Lobby - Single Tenant Floor                                                x
      - Main Lobby                                                         x
Convenience Outlets
      - Core Area                                                          x
      - Tenant Area                                                                         x
Surge Protection
      - Main Switchgear                                                    x
      - Floor Panels - Harmonic Filters                                                     x
Strobe Lighting
      - Core Areas                                                         x
      - Tenant Areas                                                                        x
      - Panel Contacts                                                     x
Telephone/Data Core Drills in Core Closets                                 x
Voice/Data Distribution
      - Incoming Service                                                   x
      - Vertical Backbone                                                                   x
      - Horizontal Distribution                                                             x
      - Grounding System                                                                    x
      - Outlets                                                                             x
Telephone Switch                                                                            x
UPS System                                                                                  x
Automatic Transfer Switch (for UPS)                                                         x
Emergency Generator (per code)                                             x
Tenant Emergency Generator                                                                  x
Battery Back-Up                                                                             x
MECHANICAL
Air Handling Units (1 per floor)                                           x
Perimeter Fan Powered VAV Boxes (Zone 15' from glass)
      - VAV Boxes provided; not installed (1 per 550 rsf)                                   x
      - Thermostats/Controls/Power/Balancing                                                x
Exhaust/Ventiliation
      - MEP Rooms                                                          x

<FN>
                                                                      x - Sub-Tenant Standards
</FN>

<PAGE>
<CAPTION>
DESCRIPTION                                                          BASE BUILDING     SUB-TENANT
-----------                                                          -------------     ----------
<S>                                                                     <C>              <C>
      - Toilet Rooms                                                       x
      - Elevator                                                           x
      - Stairs                                                             x
Medium Pressure Trunk Duct                                                 x
Low Pressure Trunk Duct                                                                     x
Duct Runouts                                                                                x
Diffusers (Perimete slot and interior)                                                      x
Interior VAV boxes (Provided; not installed; 1 per 1,350 rsf)              x
      - Thermostats/Controls/Power/Balancing                                                x
Supplemental A/C Units
      - Extra System Capacity                                                               x
      - Units (power, piping, controls)                                                     x
FIRE PROTECTION
Standpipes                                                                 x
Distribution to main loop                                                  x
      - Valved Connections                                                 x
      - Flow & Tamper Switches                                             x
Branches, drops and heades (percode)
      - Core                                                               x
      - Tenant Area (code minimum, 1 PER 225 rsf)                          x
      - Additional or Relocated Heads per Tenant Plan                                       x
      - Main Lobbies                                                       x
Extinguisher Cabinets/Extinguishers
      - Core                                                               x
      - Tenant Area                                                        x
Local Fire Alarm                                                           x
      - For Tenant Tie-in; every other floor                                                x
Fire phones (per code)
      - Fire Control Room                                                  x
      - Elevators                                                          x
      - Stairways                                                          x
Annunciator Panels (per code/specifications)                               x
PLUMBING
Wet Columns (2 per floor)                                                  x
Core Fixtures                                                              x
Electric Water Coolers                                                     x
Supplemental A/C Piping                                                                     x
Janitors Sink                                                              x
Pantries (typical floor)                                                                    x
SECURITY
Garage Control Gates                                                       x
Card readers (including power & conduit)
      - Garage Gates                                                       x
      - Building Entries                                                   x
      - Elevators                                                          x
      - Typical Floors - Suite Entry                                                        x
Cable TV (Service to Building)                                             x
      - Tenant Connection                                                                   x

<FN>
                                                                      x - Sub-Tenant Standards
</FN>
</TABLE>

<PAGE>

                                    EXHIBIT E

                             SUBTENANT'S SPACE PLAN

                                [Paragraph 2(c)]

<PAGE>

                                   EXHIBIT F

                             CONSTRUCTION SCHEDULE

                                [Paragraph 2(d)]

<TABLE>
<CAPTION>

------------------------------------------------------------------------------------------------------------------------------------
Act                                      Orig      Early      Early    JUL       AUG             SEP
ID   Description                          Dur      Start      Finish   24    31  07  14  21 28 04 11  18
------------------------------------------------------------------------------------------------------------------------------------
<S>                                        <C>     <C>       <C>       <C>   <C> <C> <C> <C> <C> <C> <C>

Pre-Construction
------------------------------------------------------------------------------------------------------------------------------------
10   Preparation of C.D.'s                 20      01AUG00   28AUG00             ###########Preparation of C.D.'s
------------------------------------------------------------------------------------------------------------------------------------
20   C.D.'s Issued For Pricing              0                28AUG00                        o C.D.'s Issued For Pricing
------------------------------------------------------------------------------------------------------------------------------------
30   File For Permit                        0                28AUG00                        o File For Permit
------------------------------------------------------------------------------------------------------------------------------------
40   Subcontractor Pricing                  8      29AUG00   08SEP00                        #####Subcontractor Pricing
------------------------------------------------------------------------------------------------------------------------------------
50   Submit Price To Owner                  0      11SEP00                                       o Submit Price To Owner
------------------------------------------------------------------------------------------------------------------------------------
60   Owner Review & Approve Pricing         6      11SEP00   18SEP00                             ####Owner Review & Approve Pricing
------------------------------------------------------------------------------------------------------------------------------------
70   Notice To Proceed                      0                18SEP00                               o Notice To Proceed
------------------------------------------------------------------------------------------------------------------------------------
80   GC To Purchase Subcontractors          5      19SEP00   25SEP00                               ####GC To Purchase Subcontractors
------------------------------------------------------------------------------------------------------------------------------------
90   Submittals                            21      25SEP00   23OCT00                               #####Submittals
------------------------------------------------------------------------------------------------------------------------------------
100  Review & Approve Submittals           21      02OCT00   30OCT00                                ####Review & Approve Submittals
------------------------------------------------------------------------------------------------------------------------------------
110  Receive Building Permit                0                25SEP00                                 o Receive Building Permit
------------------------------------------------------------------------------------------------------------------------------------
<CAPTION>

------------------------------------------------------------------------------------------------------------------------------------
                                                                                     2000
                                                                                      OCT                  NOV
                                                                         25    02   09   16  23  30  06  13  20   27
<S>                                        <C>     <C>       <C>        <C>  <C>   <C>  <C>  <C> <C> <C> <C> <C> <C>  <C>
Construction
------------------------------------------------------------------------------------------------------------------------------------

<CAPTION>
------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                  2001
                                                                                      DEC                 JAN             FEB
                                                                                04  11   18   25   01   08  15  22  29  05  1
<S>                                         <C>    <C>       <C>                <C> <C>  <C>  <C>  <C>  <C> <C> <C> <C> <C> <C>
------------------------------------------------------------------------------------------------------------------------------------
120  Floors 10 & 11                        63      19SEP00   15DEC00               ######Floors 10 & 11
------------------------------------------------------------------------------------------------------------------------------------
Substantial Completion
------------------------------------------------------------------------------------------------------------------------------------
130  Final Inspections                      5      11DEC00   15DEC00               ##Final Inspections
------------------------------------------------------------------------------------------------------------------------------------
140  Substantial Completion                 0                15DEC00                 o Substantial Completion
------------------------------------------------------------------------------------------------------------------------------------
Owner Outfitting/FFE
------------------------------------------------------------------------------------------------------------------------------------
150  Outfitting                            10      18DEC00   01JAN01                      ###Outfitting
------------------------------------------------------------------------------------------------------------------------------------
160  Occupancy                              0                01JAN01                               o Occupancy
------------------------------------------------------------------------------------------------------------------------------------

</TABLE>

                                                              INFORMAX
     The Clark Construction Group, Inc.                    BETHESDA PLACE II
                                                          BETHESDA, MARYLAND
                                                          10TH & 11TH FLOORS

<PAGE>

                                    EXHIBIT G

                         SUBLANDLORD SUPPLIED MATERIALS

                                [PARAGRAPH 2(g)]

<TABLE>
<CAPTION>
NEW        ORIG.                                                ILLEGIBLE
FLOOR      FLOOR         DEVISE       CFM      LABEL      KW       SIZE     RH\LH    MODEL       CFM-IN     SIZE
-----      -----         ------       ---      -----      --       ----     -----    -----        -----    ------
<S>           <C>    <C>  <C>         <C>        <C>       <C>       <C>      <C>    <C>            <C>       <C>   <C>     <C>
10            10     1    FTPD        1190       C         8         4        R      D35SEST       1047       10
10            10     2    FTPD        1120       C         8         4        L      D35SEST        986       10
10            10     3    FTPD         480       A         3         2        L      D35SE          422        8
10            10     4    FTPD         855       B         6         4        R      D35SEST        752        8
10            10     5    FTPD        1215       C         8         4        L      D35SEST       1069       10
10            10     6    FTPD        1115       C         8         4        R      D35SEST        981       10
10            10     7    FTPD        1290       C         8         4        L      D35SEST       1135       10
10            10     8    FTPD        1045       C         8         4        R      D35SEST        920       10
10            10     9    FTPD         670       B         5         3        L      D35SE          590        8
10            10     10   FTPD        1115       C         8         3        R      D355EST        981       10
10            10     11   FTPD        1190       C         8         4        R      D35SEST       1047       10
10            10     12   FTPD        1225       C         8         4        R      D35SEST       1078       10
10            10     13   FTPD        1050       C         8         4        L      D35SEST        924       10
10            10     14   FTPD        1170       C         8         4        R      D35SEST       1030       10
10            10     15   FTPD        1050       C         NA        4        R      D35SST         924       10
10            10     16   FTPD        1150       C         NA        4        R      D35SST        1012       10
10            10     17   FTPD        1300       C         NA        4        R      D35SST        1144       10
10            10     18   FTPD        1190       C         NA        4        R      D35SST        1047       10
10            10     19   FTPD         795       B         NA        3        R      D35S           700        8
10            10     20   FTPD        1160       C         NA        4        L      D35SST        1021       10
10            10     21   FTPD        1130       C         NA        4        R      D35SST         994       10
10            10     22   FTPD        1130       C         NA        4        R      D35SST         994       10
10            10     23   FTPD        1055       C         NA        4        L      D35SST         928       10    24690   190
11            11     4    FTPD         965       C         8         4        L      D35SEST        849       10
11            11     5    FTPD         910       C         8         4        R      D35SEST        801        8
11            11     8    FTPD         900       C         8         4        R      D35SEST        792        8
11            11     9    FTPD         730       B         5         3        L      D35SE          642        8
11            11     12   FTPD        1280       C         8         4        R      D35SEST       1126       10
11            11     14   FTPD        1280       C         8         4        R      D355EST       1126       10
11            11     16   FTPD         700       B         5         4        R      D35SE          616        8
11            11     17   FTPD         640       B         8         4        R      D35SE          563        8
11            11     18   FTPD         590       B         8         4        L      D35SE          519        8
11            11     19   FTPD        1220       C         8         4        R      D35SEST       1074       10
11            11     20   FTPD         945       C         8         4        R      D35SEST        832        8
11            11     21   FTPD         770       B         5         4        L      D35SE          678        8
11            11     22   FTPD        1225       C         8         4        R      D35SEST       1078       10
11            11     23   FTPD         850       C         8         4        R      D35SEST        748        8
11            2      18   FPTD         480       A         3         3        R      D35SE          422        8
11            5      3    FPTD         480       A         3         3        R      D35SE          422        8
11            4      17   FPTD         910       C         8                         D35SEST        801        8
11            3      3    FPTD         440       A         4         3        L      D35SE          387        6
11            3      10   FPTD         520       B         4         3        R      D35SE          458        8
11            3      12   FPTD        1180       C         8         4        L      D35SES        1038       10
11            3      14   FPTD        1050       B         5         4        L      D35SES         748        8
11            6      3    FPTD         480       A         3         3        R      D35SE          422        8
11            6      22   FPTD        1285       C         N/A       4        R      D35SEST       1131       10    19830    226
</TABLE>JOINDER AGREEMENT

         This Joinder  Agreement (the "JOINDER") is entered into as of September
8, 2000 by and  between  GENE  FUND,  LP (the "NEW  NON-PREFERRED  HOLDER")  and
INFORMAX, INC., a Delaware corporation (the "COMPANY").

         WHEREAS, the non-preferred holders of the Company who are listed on the
signature pages of the Non-Preferred Holder Rights Agreement (collectively,  the
"NON-PREFERRED   HOLDERS")  and  the  Company,   are  parties  to  that  certain
Non-Preferred  Holder Rights Agreement dated March 29, 2000 (the  "NON-PREFERRED
AGREEMENT");

         WHEREAS,  pursuant to Stock Purchase Agreements dated September 8, 2000
by and between the New Non-Preferred Holder and James Bernstein,  Jack Talmadge,
Vadim Babenko, Timothy Sullivan, Joseph Lehnen, Sergei Egorov, and James Dickey,
the New  Non-Preferred  Holder acquired shares of non-voting common stock of the
Company (the "STOCK PURCHASE AGREEMENTS"); and

         WHEREAS,  a condition to the obligations of the parties under the Stock
Purchase  Agreement is that the New Non-Preferred  Holder becomes a party to the
Non-Preferred  Agreement  concurrently  with the  execution  and delivery of the
Stock Purchase Agreements.

         NOW,  THEREFORE,  in consideration of the premises,  and other good and
valuable  consideration,   the  receipt  and  sufficiency  of  which  is  hereby
acknowledged,  the New  Non-Preferred  Holder and the  Company  hereby  agree as
follows:

         1.       The New  Non-Preferred  Holder is  hereby  made a party to the
Non-Preferred  Agreement as a "Non-Preferred  Holder" in accordance with Section
4.11 thereunder,  and the New Non-Preferred  Holder hereby agrees to be bound by
all the terms and conditions of the Non-Preferred  Agreement as a "Non-Preferred
Holder"  thereunder.  The terms and  conditions of the  Non-Preferred  Agreement
shall  apply to the  shares  of  common  stock  acquired  pursuant  to the Stock
Purchase Agreement.

         2.       The New  Non-Preferred  Holder  represents and warrants to the
Company and the other Non-Preferred  Holders that the New Non-Preferred  Holder:
(a) has  reviewed  the  Joinder  and  the  Non-Preferred  Agreement (as attached
hereto) in their entireties, and fully understands all provisions of the Joinder
and the  Non-Preferred  Agreement,  and (b) in accordance  with the terms of the
Non-Preferred  Agreement the New Non-Preferred Holder has become a Non-Preferred
Holder  under  the  Non-Preferred  Agreement  and is bound by all the  terms and
conditions of the Non-Preferred Agreement with the same effect as though the New
Non-Preferred Holder was a subscribing party to the Non-Preferred Agreement.

         3.       All   references   in   the    Non-Preferred    Agreement   to
"Non-Preferred Holder" or "Non-Preferred Holders" shall be deemed to include the
New Non-Preferred Holder.

<PAGE>

         4.       All of the terms and conditions of the Non-Preferred Agreement
are  unmodified and shall continue in full force and effect and shall be binding
upon the parties  hereto and their  respective  assigns in  accordance  with the
terms thereof.

         5.       This Joinder may be executed  (including  by facsimile) in one
or more counterparts, each of which shall be deemed an original but all of which
together will constitute one and the same instrument.

             [THE REMAINDER OF THIS PAGE INTENTIONALLY LEFT BLANK]

                                     - 2 -

<PAGE>

         IN WITNESS WHEREOF, the parties hereto have executed this Joinder as of
the date first above written.

                                     COMPANY

                                     INFORMAX, INC.

                                     By:  /s/ Alex Titomirov
                                        -----------------------------
                                        Name: Alex Titomirov
                                        Title:  CEO/Chairman

                                     NEW NONPREFERRED HOLDER

                                     GENE FUND, LP

                                     By:  /s/ William F. Snider
                                        -----------------------------
                                        Name:
                                        Title:

Source: [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00015-of-00352.parquet"}, [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00015-of-00352.parquet"}]]