<PAGE>   1
Exhibit 10.9.3

                                  DEED OF LEASE

      THIS DEED OF LEASE, dated this 9th day of August, 1996, by and between
Opus East, L.L.C., a Delaware limited liability company, ("Landlord") and 
Coherent Communications Systems Corp., a Delaware corporation ("Tenant").

                                   WITNESSETH:

      That Landlord, in consideration of the rents and mutual covenants
hereinafter set forth, does hereby lease, demise and let unto Tenant, and Tenant
does hereby hire and take from Landlord the Premises (as hereinafter defined)
which includes all of the space located in the office building ("Building") to
be constructed on the land located in Loudoun County, Virginia described on
Exhibit A attached hereto and incorporated herein by reference, the exact
acreage of such land being subject to adjustment pursuant to the terms of the
Purchase Contract (as defined in Section 16.33 hereof). The Building will be
constructed in accordance with the Work Agreement attached hereto as Exhibit B.
The land (including all easement areas appurtenant thereto) upon which the
Building is located is hereinafter referred to as the "Property"; the Property
and the Building are collectively hereinafter referred to as the "Premises"; and
the Premises and all buildings and improvements and personal property of
Landlord used in connection with the operation or maintenance thereof located
therein and thereon and the appurtenant parking facilities are hereinafter
called the "Office Complex".

      Tenant hereby accepts this Lease and the Premises upon the covenants and
conditions set forth herein and subject to any encumbrances, covenants,
conditions, restrictions and other matters of record as of the date hereof and
all applicable zoning, municipal, county, state and federal laws, ordinances and
regulations governing and regulating the use of the Premises.

      TO HAVE AND TO HOLD THE SAME, for a "term" of approximately fifteen
(15) years commencing on the earlier to occur of (i) substantial completion of
that portion of the Building to be initially occupied by Tenant as described in
the Work Agreement ("Initial Premises"), or (ii) use and occupancy by Tenant of
any portion of the Building, but in no event prior to September 1, 1997, and
ending on the 31st day of August, 2012, unless sooner terminated in the manner
provided hereinafter. The date on which the term of the Lease begins is
sometimes hereinafter referred to as the "Commencement Date".

      Following the Commencement Date, Landlord shall deliver to Tenant a
Commencement Notice which shall contain the exact Commencement Date, the number
of square feet of net rentable area contained in the Building, and other
reasonably pertinent date. If Tenant disputes the square footage as set forth in
the Commencement Notice, Tenant shall notify Landlord in writing within ten (10)
days of Landlord's delivery of the Commencement Notice. If Landlord and Tenant
are unable to resolve the dispute within twenty (20) days of Landlord's delivery
of the Commencement Notice, a measurement shall be made by a third party
mutually acceptable to Landlord and Tenant and the third party's determination
shall govern. Upon execution of the Commencement Notice by Landlord and Tenant,
the Commencement Notice shall be conclusive and binding on Tenant as to all
matters set forth therein.

      Notwithstanding anything to the contrary contained in this Lease, in the
event the Commencement Date has not occurred on or before September 1, 1997, the
terms of paragraph A(3) of the Work Agreement shall govern.

                                    ARTICLE I
                                    BASE RENT

      SECTION 1.1 BASE RENT. In consideration of the leasing aforesaid, Tenant
agrees to pay to Landlord, at 6707 Democracy Boulevard, Suite 510, Bethesda,
Maryland, 20817 or at such other place as Landlord from time to time may
designate in writing, annual rental based on the number of square feet of net
rentable area contained in the Building (even if Tenant does not occupy the
entire net rentable area of the Building) as the same are measured in accordance
with Section 16.31 below, calculated as follows:

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<TABLE>
<CAPTION>
 Lease Years                          Rate Per Sq. Ft. of Net Rentable Area
<S>                                                  <C>    
 1-5                                                 $12.25 
 6-10                                                $13.48 
 1 1-15                                              $14.82 
</TABLE>
                                                     
      The aforesaid amount is sometimes hereinafter referred to as the "Base
 Rent," and shall be payable monthly, in advance, in equal installments
 commencing on the first day of the term and continuing on the first day of each
 and every month thereafter for the next succeeding months during the balance of
 the term. If the term commences on a date other than the first day of a
 calendar month or ends on a date other than the last day of a calendar month,
 monthly rent for the first month of the term or the last month of the term, as
 the case may be, shall be prorated based upon the ratio that the number of days
 in the term within such month bears to the total number of days in such month.

                                    ARTICLE 2
                                 ADDITIONAL RENT

      SECTION 2.1 ADDITIONAL RENT. In addition to the Base Rent payable by
 Tenant under the provisions of Article 1 hereof, Tenant shall pay to Landlord
 "Additional Rent" as hereinafter provided for in this Article 2. All sums under
 this Article and all other sums and charges required to be paid by Tenant under
 the Lease (except Base Rent), however denoted, shall be deemed to be
 "Additional Rent." If any such amounts or charges are not paid at the time
 provided in the Lease, they shall nevertheless be collectible as Additional
 Rent with the next installment of Base Rent falling due.

      SECTION 2.2 DEFINITIONS. For the purposes of this Article 2, the parties
hereto agree upon the following Definitions:

      (a) "Lease Year" shall mean each twelve (12) month period commencing with
and including the month during which the term of this Lease commences, and
ending with the month during which the term of this Lease (including any
extensions or renewals) terminates.

      (b) "Real Estate Taxes" shall mean and include all personal property taxes
of Landlord relating to Landlord's personal property located in the Office
Complex and used in connection with the operation and maintenance thereof
(however, if the equipment is shared between the Office Complex and other
projects, only the proportionate share of taxes applicable to the Office Complex
shall be included), real estate taxes, water rates and charges, sewer rates and
charges, charges for public utilities, street lighting, excise levies, licenses,
permits, inspection fees, installments of special assessments, including
interest thereon, relating to the Property and Office Complex, and all other
governmental charges, general and special, ordinary and extraordinary, foreseen
as well as unforeseen, of any kind and nature whatsoever, or other tax, however
described, which is levied or assessed in substitution for any of the foregoing
by the United States of America or the state in which the Office Complex is
located or any political subdivision thereof, against Landlord or all or any
part of the Office Complex as a result of Landlord's ownership of the Property
or Office Complex, and payable during the respective Lease Year. It shall not
include any net income tax, estate tax, or inheritance tax. Tenant shall be
solely responsible for all Real Estate Taxes.

      (c) "Operating Expenses" shall mean and include all expenses incurred with
respect to the maintenance and operation of the Property and Office Complex as
determined by Landlord's accountant in accordance with generally accepted
accounting principles consistently followed, including, but not limited to,
insurance premiums, maintenance and repair costs, steam, electricity, water,
sewer, gas and other utility charges, fuel, lighting, window washing, janitorial
services, trash and rubbish removal, wages payable to employees of Landlord
whose duties are connected with the operation and maintenance of the Property
and Office Complex (but only for the portion of their time allocable to work
related to the Property and Office Complex), amounts paid to contractors or
subcontractors for work or services performed in connection with the operation
and maintenance of the Property and Office Complex including air quality
monitoring and remediation efforts, all costs of uniforms, supplies and
materials used in connection with the operation and maintenance of the Property
and Office Complex, all payroll taxes, unemployment insurance costs, vacation
allowances, and the cost of providing disability insurance or benefits,
pensions, profit sharing benefits, hospitalization, retirement or other
so-called fringe benefits to employees below the level of building manager (but
only for the portion of their time allocable to work

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related to the Property and Office Complex), and any other expense imposed on
Landlord, its contractors or subcontractors, pursuant to law or pursuant to any
collective bargaining agreement covering such employees, all services, supplies,
repairs, replacements or other expenses for maintaining and operating the
Property and Office Complex, reasonable attorneys' fees and costs in connection
with appeal or contest of real estate or other taxes or levies, and such other
expenses as may be ordinarily incurred in the operation and maintenance of an
office complex in Loudoun County and not specifically set forth herein,
including reasonable management fees, not to exceed 3% of the applicable Base
Rent plus 3% of current Operating Expenses, exclusive of electricity costs.
Until the Building is fully occupied, such management fees shall be adjusted by
multiplying the full management fee otherwise due hereunder by the percentage
of the Building occupied as of the first day of each calendar month, and the
resulting product shall be the management fee for such month. The term
"Operating Expenses" shall also include capital improvement to the Office
Complex, and replacements required for normal maintenance and repair, and
expenses incurred by Landlord in connection with sidewalks adjacent to the
Property and any pedestrian walkway system (either above or below ground) or
other public facility required by applicable law to which Landlord of the Office
Complex is from time to time subject in connection with operations of the
Property and Office Complex. Tenant shall be solely responsible for all
Operating Expenses.

      The term "Operating Expenses" shall not include Real Estate Taxes (as
hereinafter defined), repairs, restoration or other work occasioned by fire,
windstorm or other insured casualty, or occasioned by condemnation; leasing
commissions; legal expenses incident to enforcement by Landlord of the terms of
any existing or potential lease; interest or principal payments on any mortgage
or other indebtedness of Landlord; payment under any ground lease; compensation
paid to any employee of Landlord above the grade of building superintendent; any
depreciation allowance or expense; capital expenditures required by Landlord's
failure to comply with Legal Requirements (as defined in the Work Agreement);
overtime expenses to Landlord due to Landlord's defaults hereunder; any cost
representing an amount paid for first class services and/or materials to a
related person, firm, or entity to the extent such amount exceeds the amount
that would be paid for such first class services and/or materials at the then
existing market rates to an unrelated person, firm or entity; costs directly
resulting from the gross negligence or misconduct of Landlord, its employees,
agents or contractors; costs or fees relating to the defense of Landlord's title
or interest in the Property; costs and expenses incurred by Landlord in forming,
operating or maintaining the ownership entity for the Premises including legal
fees incurred in connection therewith; or costs or expenses incurred by Landlord
in financing, refinancing, pledging, selling, granting or otherwise transferring
or encumbering ownership rights in the Premises. Any costs incurred by Landlord
in connection with its construction guaranty referenced in the Work Agreement,
or in connection with repairing any latent defects discovered in the Building
during the first twelve (12) months of the term shall also be excluded from
"Operating Expenses". All items contracted for and paid directly by Tenant that
would otherwise be included within the term Operating Expenses shall be excluded
from such definition. In no event shall the Operating Expenses billed to Tenant
exceed one hundred percent (100%) of the costs incurred by Landlord for same.

      Notwithstanding the foregoing provisions of this Section 2.2, prior to or
on the Commencement Date, Tenant shall secure all utilities for the Premises in
Tenant's name and for Tenant's account. During the term of this Lease, Tenant
will pay, when due, all charges of every nature, kind or description for such
utilities furnished to the Premises or chargeable against the Premises,
including all charges for water, sewage, heat, gas, light, garbage, electricity,
telephone, steam, power, or other public or private utility services. Prior to
the Commencement Date, Tenant shall reimburse Landlord for all utilities or
services at the Premises used directly and exclusively by Tenant or its agents,
employees or contractors.

      In the event that any charge or fee is required after the Commencement
Date by the state in which the Premises are located, or by any agency,
subdivision, or instrumentality thereof, or by any utility company furnishing
services or utilities to the Premises, as a condition precedent to furnishing or
continuing to furnish utilities or services to the Premises, such charge or fee
shall be deemed to be a utility charge payable by Tenant. The provisions of this
Section 2.2 shall include, but not be limited to, any charges or fees for
present or future water or sewer capacity to serve the Premises, any charges for
the underground installation of gas or other utilities or services, and other
charges relating to the extension of or change in the facilities necessary to
provide the Premises with adequate utility services, but shall specifically
exclude any charges levied to satisfy proffered conditions as set forth in the
proffers applicable to the Office Complex dated August 10, 1988, as revised
February, 1994, a copy of which has been

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provided to Tenant. In the event that Landlord has paid any such charge or fee
after the date hereof, Tenant shall reimburse Landlord for such utility charge.

      SECTION 2.3 ADJUSTMENT OF OPERATING EXPENSES. Intentionally Deleted.

      SECTION 2.4 ESTIMATED OPERATING EXPENSES FOR INITIAL LEASE YEAR. As to the
Lease Year during which the term of this Lease commences, Landlord's estimated
amount of Operating Expenses and Real Estate Taxes (based upon the estimated
number of months of the term within such initial Lease Year) shall be Three and
no/100 Dollars per square foot of net rentable area in the Building. The actual
budget on which the estimate is based is attached hereto as Exhibit G and
incorporated herein by reference.

      SECTION 2.5 ESTIMATED EXPENSES FOR SUBSEQUENT YEAR. As to each Lease Year
after the initial Lease Year, Landlord shall estimate for each such Lease Year
the total amount of Operating Expenses. Said estimate shall be in writing and
shall be delivered or mailed to Tenant at the Premises within ninety (90) days
following the start of the Lease Year.

      SECTION 2.6 PAYMENT OF ADDITIONAL RENT. Tenant shall pay, as Additional
Rent, Operating Expenses for each Lease Year, so estimated, in equal monthly
installments, in advance, on the first day of each month during each applicable
Lease Year. If for any reason Landlord has not provided Tenant with Landlord's
estimate of Operating Expenses at least thirty one (31) days prior to the
commencement of any Lease Year, then, Tenant shall be entitled to suspend
payment of Operating Expenses until it receives Landlord's estimate of same.
Within thirty (30) days of receipt of the Operating Expense estimate, Tenant
shall pay to Landlord all amounts due for the then current Lease Year, and
during the remainder of such Lease Year, Tenant shall pay to Landlord an amount
equal to one-twelfth (1/12th) of Tenant's Expenses as noted on Landlord's
estimate.

      SECTION 2.7 RE-ESTIMATES OF TAXES AND EXPENSES. From time to time during
any applicable Lease Year, but not more than one (1) time per Lease Year,
Landlord may re-estimate the amount of Operating Expenses, and in such event
Landlord shall notify Tenant, in writing, of such re-estimate in the manner
above set forth and fix monthly installments for the then remaining balance of
such Lease Year in an amount sufficient to pay the re-estimated amount over the
balance of such Lease Year after giving credit for payments made by Tenant on
the previous estimate.

      SECTION 2.8 ADJUSTMENT OF ACTUAL EXPENSES. Upon completion of each Lease
Year, Landlord shall cause its accountants to determine the actual amount of
Operating Expenses for such Lease Year and deliver a written certification of
the amounts thereof to Tenant within ninety (90) days after the end of each
Lease Year. If Tenant has paid less than the actual Operating Expenses for any
Lease Year, Tenant shall pay such deficiency within thirty (30) days after
receipt of such statement. If Tenant has paid more than the actual Operating
Expenses for any Lease Year, Landlord shall, at Tenant's option, either (a)
refund such excess, or (b) credit such excess against the most current monthly
installment or installments due Landlord for its estimate of Operating Expenses
for the next following Lease Year. If Tenant's overpayment is greater than the
equivalent of one month of Operating Expenses, Landlord shall refund the excess
to Tenant together with interest thereon at the Default Rate. A pro rata
adjustment shall be made for a fractional Lease Year occurring during the term
of this Lease or any renewal or extension thereof based upon the number of days
of the term of this Lease during said Lease Year as compared to three hundred
sixty-five (365) days and all additional sums payable by Tenant or credits due
Tenant as a result of the provisions of this Article 2 shall be adjusted
accordingly.

      SECTION 2.9 TENANT AUDIT RIGHTS. Tenant shall have the right to examine
and audit Landlord's annual statement of Operating Expenses as presented in
Landlord's statement. Tenant shall commence its examination and if applicable,
its audit within forty five (45) days after receipt of the annual statement,
shall perform its examination and audit with diligence and continuity and shall
complete its examination and audit within one hundred twenty (120) days after
receipt of the annual statement. The cost of any such examination and audit
shall be paid by Tenant, except that, if it is determined on the basis of such
audit (or if, in accordance with the following provisions, it is otherwise
ultimately determined) that the amount of Tenants obligations for Operating
Expenses for any calendar year was overstated by more than three percent (3%),
then the reasonable cost of the audit shall be paid by Landlord. Landlord shall

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refund to Tenant any overpayment for the calendar year in question within thirty
(30) days after the amount of the overpayment has been established by the audit
or as provided in this subsection. If Tenant fails to exercise its right of
audit within the forty five (45) day period, the amount of Tenant's obligations
for Operating Expenses shall be conclusively established as the amount set forth
in the annual statement delivered by Landlord to Tenant. If, however, Tenant
timely exercises its right of audit, the amount of Tenant's obligations for
Operating Expenses shall be conclusively established as the amount determined as
a result of such audit unless, within sixty (60) days after receipt of a report
of the same from the independent auditors selected by Tenant, Landlord, at its
expense, shall contest the amount thereof, in which event Tenant shall be
entitled to pursue any legal remedies it may have to finally ascertain the
amount thereof and, if appropriate, a refund on account thereof.

      SECTION 2.10 TAXES AND OTHER ADDITIONAL RENT. Beginning on the
Commencement Date and continuing throughout the Term of the Lease, Tenant shall
be responsible for all Real Estate Taxes. Tenant shall pay all amounts due
within thirty (30) days of receipt of written request and an invoice therefor,
including a copy of the tax bill. If by law any special assessment is payable
(without default) in installments (whether or not interest shall accrue on the
unpaid balance of such special assessment), and if Landlord elects to pay same
in installments, Tenant shall pay all amounts due in connection therewith,
together with any interest accrued, in installments within thirty (30) days of
receipt of Landlord's written request and invoice therefor. Landlord shall be
responsible for all installments of special assessments (including interest
accrued on the unpaid balance) which are payable prior to the Commencement Date
and after the termination date of the term of this Lease.

      Further, Tenant shall pay, also as Additional Rent, all other sums and
charges required to be paid by Tenant under this Lease, and any tax or excise on
rents, gross receipts tax, or other tax, however described, which is levied or
assessed by the United States of America or the state in which the Office
Complex is located or any political subdivision thereof, against Landlord in
respect to the Base Rent, Additional Rent, or other charges reserved under this
Lease or as a result of Landlord's receipt of such rents or other charges
accruing under this Lease but only to the extent such levy, tax, assessment or
charge on rent shall be expressly in lieu of or in substitution for any existing
Real Estate Taxes; provided, however, tenant shall have no obligation to pay net
income taxes of Landlord.

      SECTION 2.11 TENANT'S RIGHT TO CONTEST REAL ESTATE TAXES. Tenant shall
have the right at its own expense to contest the amount or validity, in whole or
in part, of any Real Estate Taxes by appropriate proceedings diligently
conducted in good faith, but only after payment of such Real Estate Taxes,
unless such payment, or a payment thereof under protest, would operate as a bar
to such contest or interfere materially with the prosecution thereof, in which
event, notwithstanding the provisions of Article 2, Tenant may postpone or defer
payment of such Real Estate Taxes if (a) neither the Premises nor any portion
thereof would, by reason of such postponement or deferment, be in danger of
being forfeited or lost, and (b) Tenant shall have deposited with Landlord cash
or a letter of credit payable to Landlord issued by a national bank or federal
savings and loan association in the amount of the Real Estate Taxes so contested
and unpaid. If, during the continuance of such proceedings, Landlord shall, from
time to time, reasonably deem the amount deposited, as aforesaid, insufficient,
Tenant shall, upon demand of Landlord, make additional deposits of such
additional sums of money or such additional certificates of deposit as Landlord
may reasonably request. Upon failure of Tenant to make such additional deposits
within thirty (30) days, the amount theretofore deposited may be applied by
Landlord to the payment, removal and discharge of such Real Estate Taxes, and
the interest, fines and penalties in connection therewith, and any reasonable
costs, fees (including reasonable attorney's fees) and other liability
(including costs incurred by Landlord, but excluding consequential or punitive
damages) accruing in any such proceedings. Upon the termination of any such
proceedings, Tenant shall pay the amount of such Real Estate Taxes or part
thereof, if any, as finally determined in such proceedings, the payment of which
may have been deferred during the prosecution of such proceedings, together with
any reasonable costs, fees (including reasonable attorney's fees), interest,
penalties, fines and other liability in connection therewith, and upon such
payment Landlord shall return all amounts deposited with it with respect to the
contest of such Real Estate Taxes, as aforesaid, or, at the written direction of
Tenant, Landlord shall make such payment out of the funds on deposit with
Landlord and the balance, if any, shall be returned to Tenant.

      Tenant shall be entitled to the refund of any Real Estate Taxes, penalty,
fine and interest thereon received by Landlord which has been paid by Tenant or
which has been paid by Landlord but for which

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Landlord has been previously reimbursed in full by Tenant, such amount to be
paid within thirty (30) days of receipt by Landlord. Landlord shall not be
required to join in any proceedings referred to in this Section 2.11 unless the
provisions of any law, rule or regulation at the time in effect shall require
that such proceedings be brought by or in the name of Landlord, in which event
Landlord shall join in such proceedings or permit the same to be brought in
Landlord's name upon compliance with such conditions as Landlord may reasonably
require. Landlord shall not ultimately be subject to any liability for the
payment of any fees, including attorney's fees, costs and expenses in connection
with such proceedings. Tenant agrees to pay all such fees (including reasonable
attorney's fees), costs and expenses or, on demand, to make reimbursement to
Landlord for such payment. During the time when any such amount is on deposit
with Landlord, and prior to the time when the same is returned to Tenant or
applied against the payment, removal or discharge of Real Estate Taxes, as above
provided, Tenant shall be entitled to receive all interest paid thereon, if any.
Landlord agrees to cooperate with Tenant's efforts in connection with this
Section 2. 11, at no cost or expense to Landlord.

      SECTION 2.12 LANDLORD'S RIGHT TO CONTEST REAL ESTATE TAXES. In addition to
the right of Tenant under Section 2.11 to contest the amount or validity of Real
Estate Taxes, Landlord shall also have the right to contest same; provided
however, Landlord shall first give Tenant written notice of such intention and
Tenant shall have twenty (20) days from the date of Landlord's notice within
which to give Landlord written notice that Tenant will contest the Real Estate
Taxes, and to thereafter diligently pursue same. Landlord shall not be obligated
to contest Real Estate Taxes, and any such contest shall be by appropriate
proceedings conducted in the name of Landlord or in the name of Landlord and
Tenant. If Landlord elects to contest the amount or validity, in whole or in
part, of any Real Estate Taxes, such contests by Landlord shall be at Landlord's
expense, provided, however, that if the amounts payable by Tenant for Real
Estate Taxes are reduced (or if a proposed increase in such amounts is avoided
or reduced) by reason of Landlord's contest of Real Estate Taxes, Tenant shall
reimburse Landlord for costs incurred by Landlord in contesting Real Estate
Taxes, but such reimbursements shall not be in excess of the amount saved by
Tenant by reason of Landlord's actions in contesting such Real Estate Taxes. If
Real Estate Taxes are retroactively increased following a contest by Landlord,
Tenant shall not be responsible for such incremental increase.

      SECTION 2.13 EVIDENCE OF PAYMENT. Landlord covenants to furnish Tenant
written evidence of the payment of any Real Estate Taxes (i.e. paid tax bills)
for which Tenant has already paid Landlord.

      SECTION 2.14 ESCROW FOR TAXES AND ASSESSMENTS. At Landlord's written
demand after any Event of Default and for as long as such Event of Default is
uncured, Tenant shall pay to Landlord the known yearly Real Estate Taxes
assessments and other impositions payable with respect to the Property and
Office Complex in monthly payments equal to one-twelfth of the known yearly Real
Estate Taxes, assessments and other impositions next payable with respect to the
Property and Office Complex. If the total monthly payments made by Tenant
pursuant to this Section 2.14 shall exceed the amount of payments necessary for
said Real Estate Taxes, such excess shall be credited on subsequent monthly
payments of the same nature or, at Tenant's option, promptly refunded, but if
the total of such monthly payments so made under this paragraph shall be
insufficient to pay such Real Estate Taxes when due, then Tenant shall pay to
Landlord such amount as may be necessary to make up the deficiency. Payment by
Tenant of Real Estate Taxes under this section shall be considered as
performance of such obligation under the provisions of Section 2.14 hereof.

                                    ARTICLE 3
                            BASE AND ADDITIONAL RENT

      SECTION 3.1 INTEREST AND LATE FEE ON PAST DUE OBLIGATIONS. Any installment
of Base Rent, Additional Rent, or other charges to be paid by Tenant accruing
under the provisions of this Lease which shall not be paid within ten (10) days
of the date when due, shall bear interest at the rate ("Default Rate") of
fifteen percent (15%) per annum from the date when the same is due until the
same shall be paid, but if such rate exceeds the maximum interest rate permitted
by law, such rate shall be reduced to the highest rate allowed by law under the
circumstances. In addition, any installments of Base Rent or Additional Rent or
any other charges payable by Tenant under the provisions hereof which shall not
be paid when due and which remain unpaid ten (10) days thereafter shall be
subject to a late payment fee of five percent (5%) of the unpaid amount.

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      SECTION 3.2 RENT INDEPENDENT. Except as otherwise expressly set forth
herein, Tenant's covenants to pay the Base Rent and the Additional Rent are
independent of any other covenant, condition, provision or agreement herein
contained, and nothing herein contained shall be deemed to suspend or delay the
payment of any amount of money or charge at the time the same becomes due and
payable hereunder, or limit any other remedy of Landlord. Base Rent and
Additional Rent are sometimes collectively referred to as "Rent." Except as
otherwise expressly set forth in this Lease, Rent shall be payable without
deduction, offset, prior notice or demand, in lawful money of the United States.

      SECTION 3.3 SECURITY DEPOSIT. Intentionally Deleted.

                                    ARTICLE 4
                             POSSESSION OF PREMISES

      SECTION 4.1 DELAYED OR EARLIER POSSESSION. If Landlord shall be unable to
give possession of the Initial Premises on the date of the commencement of the
term because the construction of the Building or the completion of the Initial
Premises has not been sufficiently completed to make the Initial Premises ready
for occupancy or for any other reason, Landlord shall not be subject to any
claims, damages or liabilities for the failure to give possession on said date
except for hold over rent as provided above and except as set forth in the Work
Agreement. Under said circumstances, the rent reserved and Tenant's covenant to
pay same shall not commence until possession of the Initial Premises is given or
the Initial Premises are ready for occupancy, whichever is earlier. Failure to
give possession on the date of commencement of the term shall in no way affect
the validity of this Lease or the obligations of Tenant hereunder, nor shall the
same be construed in any way to extend the expiration date of the term. If
Tenant is given and accepts possession of the Premises or a portion thereof on a
date earlier than the date above specified for commencement of the term the rent
reserved herein and all covenants, agreements and obligations herein and the
term of this Lease shall commence on the date that possession is given to
Tenant.

      SECTION 4.2 EFFECT OF POSSESSION. Intentionally Deleted.

      SECTION 4.3 PERMITTED USE. The Premises shall be occupied and used by
Tenant for general office purposes, including, but not limited to, research,
development and testing of telecommunications equipment, and for no other
purpose, subject to the covenants and agreements hereinafter contained. Tenant
shall not use or permit the Premises to be used for any other purpose without
the prior written consent of Landlord.

      SECTION 4.4 TENANT'S COMPLIANCE WITH ENVIRONMENTAL LAWS. Tenant shall at
all times and in all respects comply with all federal, state and local laws,
ordinances and regulations ("Hazardous Materials Laws") relating to the
industrial hygiene, environmental protection or the use, analysis, generation,
manufacture, storage, presence, disposal or transportation of any oil, petroleum
products, flammable explosives, asbestos, urea formaldehyde, polychlorinated
biphenyls, radioactive materials or waste, or other hazardous, toxic,
contaminated or polluting materials, substances or wastes, including without
limitation any "hazardous substances," "hazardous wastes," "hazardous materials"
or "toxic substances" under any such laws, ordinances or regulations
(collectively, "Hazardous Materials"). The foregoing shall not be construed to
prohibit Tenant from storing and using reasonable quantities of customary office
and cleaning supplies in the Building as contemplated by the permitted use
contained in Section 4.3 above.

      Tenant shall at its own expense procure, maintain in effect and comply
with all conditions of any and all permits, licenses and other governmental and
regulatory approvals required for Tenant's use of the Premises and Office
Complex including, without limitation, discharge of (appropriately treated)
materials or waste into or through any sanitary sewer system serving the
Premises and Office Complex. Except as discharged into the sanitary sewer in
strict accordance and conformity with all applicable Hazardous Materials Laws,
Tenant shall cause any and all Hazardous Materials to be removed from the
Premises and Office Complex and transported solely by duly licensed haulers to
duly licensed facilities for final disposal of such Hazardous Materials and
wastes. Tenant shall in all respects, handle, treat, deal with and manage any
and all Hazardous Materials in, on, under or about the Premises and Office
Complex in complete

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<PAGE>   8
conformity with all applicable Hazardous Materials Laws and prudent industry
practices regarding the management of such Hazardous Materials. All reporting
obligations to the extent imposed upon Tenant by Hazardous Materials Laws are
solely the responsibility of Tenant. Upon expiration or earlier termination of
this Lease, Tenant shall cause all Hazardous Materials (except to the extent
such Hazardous Materials are generated, stored, released or disposed of during
the term of this Lease by Landlord) to be removed from the Premises and Office
Complex and transported for use, storage or disposal in accordance and in
compliance with all applicable Hazardous Materials Laws. Tenant shall not take
any remedial action in response to the presence of any Hazardous Materials in,
on, about or under the Premises, the Building, the Office Complex or the
Property, nor enter into any settlement agreement, consent, decree or other
compromise in respect to any claims relating to any way connected with the
foregoing without first Landlord of Tenant's intention to do so and affording
Landlord ample opportunity to appear, intervene or otherwise appropriately
assert and protect Landlord's interest with respect thereto. In addition, at
Landlord's written request, at the expiration of the term of this Lease or
within sixty (60) days following the date of such request, whichever is later,
Tenant shall remove all tanks or fixtures which were placed on the Premises and
Office Complex during the term of this Lease and which contain, or are
contaminated with, Hazardous Materials.

      Tenant shall immediately notify Landlord in writing of (a) any
enforcement, clean-up, removal or other governmental or regulatory action
instituted, completed or threatened pursuant to any Hazardous Materials Laws;
(b) any claim made or threatened by any person against Landlord, or the Premises
or the Office Complex, relating to damage, contribution, cost recovery,
compensation, loss or injury resulting from or claimed to result from any
Hazardous Materials; and (c) any reports made to any environmental agency
arising out of or in connection with any Hazardous Materials in, on or about the
Premises or the Office Complex, or with respect to any Hazardous Materials
removed from the Premises or the Office Complex, including, any complaints,
notices, warnings, reports or asserted violations in connection therewith.
Tenant shall also provide to Landlord, as promptly as possible, and in any event
within five business days after Tenant first receives or sends the same, copies
of all claims, reports, complaints, notices, warnings or asserted violations
relating in any way to the Hazardous Materials in or on the Office Complex or
Premises. Upon written request of Landlord (to enable Landlord to defend itself
from any claim or charge related to any Hazardous Materials Law), Tenant shall
promptly deliver to Landlord notices of hazardous waste manifests reflecting the
legal and proper disposal of all such Hazardous Materials removed or to be
removed from the Premises or Office Complex. All such manifests shall list the
Tenant or its agent as a responsible party and in no way shall attribute
responsibility for any such Hazardous Materials to Landlord.

      SECTION 4.5 LANDLORD'S COMPLIANCE WITH ENVIRONMENTAL LAWS. Landlord
covenants not to bring onto the Office Complex or into the Building, or common
areas, any Hazardous Materials, as that term is defined herein. Notwithstanding
the foregoing, Tenant recognizes and acknowledges that Landlord or its agents
may use and store within the Building reasonable quantities of customary office
and cleaning supplies; provided such items are stored, used and disposed of in
accordance with applicable federal, state or local law.

                                    ARTICLE 5
                            SERVICES AND MAINTENANCE

      SECTION 5.1 SERVICES PROVIDED BY LANDLORD. Subject to the provisions of
Article 2 hereof, Landlord shall provide the following services on all days
excepting Saturdays, Sundays, holidays, and as otherwise stated in this Section
5.1:

      (a) JANITORIAL SERVICE. Both Landlord and Tenant acknowledge that Tenant
shall provide janitorial and CHAR services for the entire Building at its sole
cost and expense.

      (b) PARKING FACILITIES AND LANDSCAPED AREAS. Maintenance in good order,
condition and repair and appropriate illumination of the parking facilities and
all driveways leading thereto and keeping the same free from any unreasonable
accumulation of snow. Landlord shall keep and maintain the landscaped area and
parking facilities in a neat, safe and orderly condition.

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<PAGE>   9
      (c) HEATING AND AIR CONDITIONING. Heating and air conditioning in amounts
and ranges required by Tenant's Plans (as defined in the Work Agreement) during
regular business hours as the same are set by Tenant from time to time. Except
in the case of an emergency, Landlord will give Tenant at least five (5)
business days prior notice if Landlord intends to interrupt any of the services
required to be furnished by Landlord. Provided Tenant gives Landlord notice of
its need for overtime HVAC service during normal business hours, Landlord shall
provide such service and Tenant shall only be responsible for the actual utility
costs relating to such overtime service.

      SECTION 5.2 TENANT'S UTILITY SERVICES. During the term of this lease,
Tenant will pay, when due, all charges of every nature, kind or description for
utilities furnished to the Premises including all charges for water, sewage,
heat, gas, light, garbage, electricity, telephone, power or other public or
private utility services. Prior to the Commencement Date, Tenant shall pay for
all utilities or services at the Premises directly and exclusively used by
Tenant or its agents, employees or contractors.

      SECTION 5.3 OTHER PROVISIONS RELATING TO SERVICES. Except as specifically
provided in this Section 5.3, no interruption in, or temporary stoppage of, any
of the aforesaid services caused by repairs, renewals, improvements'
alterations, strikes, lockouts, labor controversy, accidents, inability to
obtain fuel or supplies, or other Unavoidable Delays shall be deemed an eviction
or disturbance of Tenant's use and possession, or render Landlord liable for
damages, by abatement of rent or otherwise or relieve Tenant from any obligation
herein set forth. In no event shall Landlord be required to provide any service
in excess of that permitted by involuntary guidelines or laws, ordinances or
regulations of governmental authority. Landlord reserves the right, from time to
time, to make reasonable and non-discriminatory modifications to the standards
for utilities and services set forth in this Article 5 upon providing not less
than thirty (30) days' notice to Tenant. If utility services to the Premises are
interrupted for more than five (5) consecutive business days and, as a result
thereof, Tenant ceases operating at the Premises, Rent shall abate on a daily
basis beginning on the sixth (6th) consecutive business day and continuing until
services are restored.

      SECTION 5.4 EFFECTS ON UTILITIES. Tenant shall not connect with electric
current or water pipes, except through existing electrical or water outlets
already in the Premises, any apparatus or device for the purposes of using
electric current or water.

      SECTION 5.5 PARK DUES. Tenant acknowledges that the Property is part of a
larger development and that certain dues or assessments are owed on a regular
periodic basis for additional services or maintenance pursuant to covenants,
conditions and restrictions of record. Tenant will pay all such dues
attributable to the Property as Additional Rent, or directly, if possible.

      SECTION 5.6 MAINTENANCE. Subject to Tenant's reimbursement obligations and
Tenant's right to assume the property management functions contained in Article
2 and Section 5.7 of this Lease respectively, Landlord shall keep and maintain
in good order and repair consistent with a first class office building in
Loudoun County the Premises and the remainder of the Office Complex including
but not limited to, the exterior structure and systems, the walls, load bearing
elements, foundations, pipes and conduits, roof and common areas that form a
part of the Premises, parking areas, elevators and the building standard
mechanical, electrical, HVAC and plumbing systems; provided, however, Tenant
shall perform certain maintenance obligations as required by Section 9.1 hereof.

      SECTION 5.7 TENANT'S ASSUMPTION OF PROPERTY MANAGEMENT FUNCTIONS. Tenant
shall have the right, at its option, to assume all property management functions
which are the responsibility of Landlord under this Lease. In such event, Tenant
shall provide written notice of such election to Landlord and shall execute and
deliver to Landlord an Assumption of Property Management Services Certificate
("Assumption Certificate") to be prepared by Landlord in form and content
reasonably satisfactory to Tenant, in which Tenant agrees to undertake all
management and maintenance obligations with respect to the Property and the
Building and to comply with the terms of all existing third-party contracts for
the provision of such services. Landlord agrees that the form and content of the
service contracts which it enters into in connection with the Premises shall be
consistent with then current industry standards and shall contain a provision
permitting Landlord to terminate same upon the giving of no more than sixty (60)
days prior written notice. Landlord shall provide the service contracts to
Tenant for its review upon request. Such assumption shall be effective as of the
date specified in the Assumption

                                        9
<PAGE>   10
Certificate, which shall in no event be more than 60 days from the date of
initial notice. Upon execution and delivery of the Assumption Certificate, all
management fees shall be excluded from Operating Expenses as of the date
specified in the Assumption Certificate.

                                    ARTICLE 6
                                    INSURANCE

      SECTION 6.1 LANDLORD'S CASUALTY INSURANCE OBLIGATIONS. Landlord shall keep
the Office Complex insured in an amount equivalent to the full replacement value
thereof (excluding foundation, grading and excavation costs) against:

      (a) loss or damage by fire; and

      (b) such other risk or risks of a similar or dissimilar nature as are now
or may be customarily covered with respect to buildings and improvements similar
in construction, general location, use, occupancy and design to the Office
Complex, including, but without limiting the generality of the foregoing,
windstorms, hail, explosion, vandalism, malicious mischief, civil commotion, and
such other coverage as may be deemed necessary by Landlord, provided such
additional coverage is obtainable and provided such additional coverage is such
as is customarily carried with respect to buildings and improvements similar in
construction, general location, use, occupancy and design to the Office Complex.

      These insurance provisions shall in no way limit or modify any of the
obligations of Tenant under any provision of this Lease. Landlord agrees that
such policy or policies of insurance shall permit releases of liability as
provided herein and/or waiver of subrogation clause in favor of Tenant and
Landlord waives, releases and discharges Tenant from all claims or demands
whatsoever which Landlord may have or acquire arising out of damage to or
destruction of the Office Complex or loss of use thereof occasioned by fire or
other casualty, which claim or demand may arise because of the negligence or
fault of Tenant, its agents, employees, customers or business invitees, or
otherwise, and Landlord agrees to look to the insurance coverage only in the
event of such loss. Notwithstanding the foregoing, Tenant shall be obligated to
pay the rental called for hereunder in the event of damage to or destruction of
the Premises or the Office Complex if such damage or destruction is occasioned
by the negligence or fault of Tenant, its agents or employees, such fault to be
established by arbitration or a judicial proceeding. Insurance premiums paid for
insurance coverage required under this Article 6 by Landlord shall be a portion
of the "Operating Expenses" described in Article 2 hereof.

      SECTION 6.2 TENANT'S CASUALTY INSURANCE OBLIGATIONS. Tenant shall keep all
of its machinery, equipment, furniture, fixtures and personal property which may
be located in, upon, or about the Premises insured for the benefit of Tenant in
an amount equivalent to the full insurable value thereof against:

      (a) loss or damage by fire; and

      (b) such other risk or risks of a similar or dissimilar nature as are now,
or may in the future be, customarily covered with respect to a tenant's
machinery, equipment, furniture, fixtures, personal property and business
located in a building similar in construction, general location, use, occupancy
and design to the Office Complex, including, but without limiting the
generality of the foregoing, windstorms, hail, explosions, vandalism theft
malicious mischief, civil commotion, and such other coverage as Tenant may deem
appropriate or necessary.

      Tenant agrees that such policy or policies of insurance shall permit
release of liability as provided herein and/or waiver of subrogation clause as
to Landlord and Tenant waives, releases and discharges Landlord, its agents,
employees, and contractors from all claims or demands whatsoever which Tenant
may have or acquire arising out of damage to or destruction of the machinery,
equipment, furniture, fixtures, personal property, and loss of use thereof
occasioned by fire or other casualty, whether such claim or demand may arise
because of the negligence or fault of Landlord, its agents, employees,
contractors or otherwise, and Tenant agrees to look to the insurance coverage
only in the event of such loss.

                                       10
<PAGE>   11
      SECTION 6.3 LANDLORD'S LIABILITY AND OTHER INSURANCE OBLIGATIONS. Landlord
shall, as a portion of the Operating Expenses defined in Article 2, maintain,
for its benefit and the benefit of its managing agent and Tenant, general public
liability insurance against claims for personal injury, death or property damage
occurring upon, in or about the Office Complex, such insurance to afford
protection to Landlord and its managing agent of a combined single limit of Two
Million and No/100 Dollars ($2,000,000.00) in respect to the injury, death or
property damage arising out of any accident or occurrence. In addition, Landlord
shall carry employer's liability insurance with a minimum limit of $1,000,000
for bodily injury; excess liability insurance over the public and employer's
liability insurance required above with combined, minimum coverage of
$5,000,000; worker's compensation insurance in statutory limits; and such other
insurance coverage or increased amounts of referenced coverages or deductibles
as is customarily carried in respect of comparable buildings in Loudoun County,
Virginia. Landlord agrees to include in its general public liability insurance
policy the contractual liability coverage insuring Landlord's indemnification
obligations provided for herein. Any such coverage shall be deemed primary to
any liability coverage secured by Tenant. Such insurance shall also afford
coverage for all claims based upon acts, omissions, injury or damage, which
claims occurred or arose (or the onset of which occurred or arose) in whole or
in part during the policy period.

      At Tenant's request, Landlord shall furnish Tenant with a certificate of
insurance certifying that the insurance coverage required of Landlord pursuant
to this Article 6 is in effect. Any insurance required by the terms of this
Lease to be carried by Landlord may be under a blanket policy (or policies)
covering the other properties of the Landlord and/or its related or affiliated
entities so long as the insurance requirements set forth herein are satisfied.
If such insurance is maintained under a blanket policy, Landlord shall procure
and deliver to Tenant a statement from the insurer or general agent of the
insurer setting forth the coverage maintained and the amounts thereof allocated
to the risks intended to be insured hereunder.

      SECTION 6.4 TENANT'S LIABILITY INSURANCE OBLIGATIONS. Tenant shall, at
Tenant's sole cost and expense but for the mutual benefit of Landlord, its
managing agent and Tenant, maintain general public liability insurance against
claims for personal injury, death or property damage occurring upon, in or about
the Premises, such insurance to afford protection to Landlord, its managing
agent and Tenant of a combined single limit of Two Million and No/100 Dollars
($2,000,000.00) in respect to the injury, death or property damage arising out
of any accident or occurrence in the Office Complex. In addition, Tenant shall
carry employer's liability insurance with a minimum limit of $500,000 for bodily
injury; worker's compensation insurance in statutory limits; and excess
liability insurance over the public and employer's liability insurance required
above with combined, minimum coverage of $5,000,000. Such policies of insurance
shall be written in companies reasonably satisfactory to Landlord, naming
Landlord and its managing agent as additional insureds thereunder (on a primary
basis), and such policies, or a memorandum or certificate of such insurance,
shall be delivered to Landlord with evidence reasonably satisfactory to Landlord
that the premium thereon has been paid. At such time as insurance limits
required of tenants in office buildings in the area in which the Office Complex
is located are generally increased to greater amounts, Landlord shall have the
right to require such greater limits as may then be customary. Tenant agrees to
include in such policy the contractual liability coverage insuring Tenant's
indemnification obligations provided for herein. Any such coverage shall be
deemed primary to any liability coverage secured by Landlord. Such insurance
shall also afford coverage for all claims based upon acts, omissions, injury or
damage, which claims occurred or arose (or the onset of which occurred or arose)
in whole or in part during the policy period.

      SECTION 65 INDEMNIFICATIONS. Tenant agrees to indemnify, protect, defend
and hold Landlord and Landlord's shareholders, employees, lender and managing
agent harmless from and against any and all claims, costs, liabilities, actions,
and damages, including, without limitation, attorneys' fees and costs on behalf
of any person or persons, firm or firms, corporation or corporations, arising
from any breach or default on the part of Tenant in the performance of any
covenant or agreement on the part of Tenant to be performed, pursuant to the
terms of this Lease, or arising from any act or negligence on the part of Tenant
or its agents, contractors, servants, employees or licensees, or arising from
any accident, injury or damage to the extent caused by Tenant, its agents, and
employees to any person, firm or corporation occurring during the term of this
Lease or any renewal thereof, in or about the Premises and Office Complex, and
from and against all reasonable costs, reasonable counsel fees, expenses and
liabilities incurred in or about any such claim or action or proceeding brought
thereon; and in case any action or proceeding be brought against Landlord or its
managing agent by reason of any such claim,

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<PAGE>   12
Tenant, upon notice from Landlord, covenants to resist or defend such action or
proceeding by counsel reasonably satisfactory to Landlord. Tenant's
indemnification shall not apply to losses, claims, costs and the like arising as
a result of the negligence or willful misconduct of Landlord or its agents.

      Landlord hereby waives all claims against Tenant for damage to any
property or injury to, or death of, any person in, upon, or about the Office
Complex, including the Premises, arising at any time and from any cause other
than by reason of the negligent or willful misconduct, or negligent omission of
Tenant, its employees, agents, contractors or representatives. Landlord shall,
and hereby agrees to, indemnify and hold Tenant harmless from any damage to any
property or injury to, or death of, any person arising from Landlord's breach of
its obligation hereunder, unless the damage is caused by the negligence or
willful misconduct of the Tenant, its employees, agents, contractors or
representatives. Landlord's foregoing indemnity shall include reasonable
attorneys' fees, investigation costs, and all other reasonable costs and
expenses incurred by Tenant in any connection therewith; and in case any action
or proceeding be brought against Tenant or its managing agent by reason of any
such claim, Landlord, upon notice from Tenant, covenants to resist or defend
such action or proceeding by counsel reasonably satisfactory to Tenant. The
provisions of this paragraph shall survive the termination of this Lease with
regard to any occurrence prior to such termination and any resulting damage,
injury, or death. If Tenant is made a party to any litigation commenced by or
against Landlord or relating to this Lease, and provided that in any such
litigation Tenant is not adjudicated in a court of final appeal to be at fault,
then Landlord shall pay all costs and expenses, including actual, but not
unreasonable attorneys' fees and court costs incurred by or imposed upon Tenant
because of any such litigation, and the amount of all such costs and expenses
including actual but not unreasonable attorneys' fees and court costs shall be a
demand obligation owing by Landlord to Tenant.

      SECTION 6.6 TENANT'S WAIVER. Except to the extent covered by Landlord's
indemnity in Section 6.5 above, Tenant agrees, to the extent not expressly
prohibited by law, that Landlord, its agents, employees and servants shall not
be liable, and Tenant waives all claims for damage to property and business
sustained during the term of this Lease by Tenant occurring in or about the 
Office Complex, resulting directly or indirectly from any existing or future
condition, defect, matter or thing in the Premises, the Office Complex, or any
part thereof, or from equipment or appurtenances becoming out of repair or from
accident, or from any occurrence or act or omission of Landlord, its agents,
employees or servants, or any tenant or occupant of the Building or any other
person. This paragraph shall apply especially but not exclusively, to damage
caused by aforesaid or by the flooding of basements or other subsurface areas,
or by refrigerators, sprinkling devices, air conditioning apparatus, water,
snow, frost, steam, excessive heat or cold, falling plaster, broken glass,
sewage, gas, odors or noise, or the bursting or leaking of pipes or plumbing
fixtures, and shall apply equally, whether any such damage results from the act
or omission of other tenants or occupants in the Office Complex or any other
persons, and whether such damage be caused by or result from any of the
aforesaid, or shall be caused by or result from other circumstances of a similar
or dissimilar nature.

      SECTION 6.7 LANDLORD'S DEDUCTIBLE AND TENANT'S PROPERTY. Provisions herein
to the contrary notwithstanding, in the event any damage to the Office Complex
results directly and exclusively from any act or omission of Tenant, its agents,
employees or invitees, and all or any portion of Landlord's loss is
"deductible," Tenant shall pay to Landlord the amount of such deductible loss
(not to exceed $1,000 per event).

      SECTION 6.8 TENANT'S PROPERTY. All property in the Office Complex or on
the Premises belonging to Tenant, its agents, employees, invitees or otherwise
located at the Premises, shall be at the risk of Tenant only, and Landlord,
except to the extent covered by Landlord's indemnity in Section 6. 5, shall not
be liable for damage thereto or theft, misappropriation or loss thereof and
Tenant agrees to defend and hold Landlord, its agents, employees and servants
harmless and indemnify them against claims and liability for injuries to such
property.

      SECTION 6.9 INCREASE IN INSURANCE. Intentionally Deleted.

      SECTION 6.10 TENANT'S FAILURE TO INSURE. In the event Tenant fails to
provide Landlord with evidence of insurance required under this Article 6 within
thirty (30) days of Landlord's written request therefor, but in any event at
least ten (l0) days prior to the expiration of the existing policy, Landlord

                                       12
<PAGE>   13
may, but shall not be obligated to, without further demand upon Tenant, and
without waiving or releasing Tenant from any obligation contained in this Lease,
effect such insurance and Tenant agrees to repay, upon demand, all such sums
incurred by Landlord in effecting such insurance. All such sums shall become a
part of the Additional Rent payable hereunder, but no such payment by Landlord
shall relieve Tenant from any default under this Lease.

                                    ARTICLE 7
                       CERTAIN RIGHTS RESERVED BY LANDLORD

      SECTION 7.1 RIGHTS RESERVED BY LANDLORD. Landlord reserves the following
rights exercisable without notice and without liability to Tenant and without
effecting an eviction, constructive or actual, or disturbance of Tenant's use or
possession, or giving rise to any claim for set off or abatement of rent except
as otherwise expressly set forth herein:

      (a) RETAIN KEYS. To retain at all times and to use in appropriate
instances keys to all doors within and into the Premises, except keys to the
"secure areas" designated on the Tenant's Plans, as such areas may be changed by
Tenant from time to time following written notice to Landlord. No locks shall be
changed (except locks in or to the "secure areas") without the prior written
notice to Landlord. This provision shall not apply to Tenant's safes, or other
areas maintained by Tenant for the safety and security of monies, securities,
negotiable instruments or similar items. To the extent reasonably possible, (i)
Landlord shall give Tenant notice prior to entering the Premises, (ii)
Landlord's entry shall be during normal business hours, and (iii) if required by
Tenant, Landlord shall be accompanied by a representative of Tenant.

      (b) MAKE REPAIRS. To make repairs, alterations, additions, or
improvements, whether structural or otherwise, in and about the Office Complex,
or any part thereof, and for such purposes to enter upon the Premises, and
during the continuation of any of said work to temporarily close doors,
entryways, public spaces, and corridors in the Office Complex and to interrupt
or temporarily suspend services and facilities, so long as Landlord at all times
uses its best commercially reasonable efforts and endeavors in good faith to
limit any interference with the conduct of Tenant's business or its occupancy
and use of the Premises. If, as a result of Landlord's material and adverse
interference, Tenant ceases operating at the Premises for five (5) consecutive
business days, Tenant shall be entitled to an abatement of Rent on a daily basis
beginning on the sixth (6th) consecutive business day and continuing until the
earlier of(i) cessation of such material and adverse interference, or (ii) the
date on which Tenant resumes business operations at the Premises. If as a result
of Landlord's material and adverse interference, Tenant ceases operating at the
Premises for ninety (90) consecutive business days, Tenant shall be entitled to
terminate the Lease by delivering written notice to Landlord prior to the one
hundredth (100th) consecutive business day of material and adverse interference.
In exercising its right to make repairs, alterations and the like, to the extent
reasonably possible, (i) Landlord shall give Tenant notice prior to entering the
Premises, (ii) Landlord's entry shall be during normal business hours, and (iii)
if required by Tenant, Landlord shall be accompanied by a representative of
Tenant.

      (c) REGULATE HEAVY EQUIPMENT. To approve the weight, size and location of
safes and other heavy equipment and articles in and about the Premises and the
Office Complex and to require all such items to be moved into and out of the
Office Complex and the Premises only at such times and in such manner as
Landlord shall direct in writing excluding initial move in and final move out.
Landlord hereby consents to the weight, size and location of equipment shown on
Tenant's Plans.

      SECTION 7.2 EMERGENCY ENTRY. Landlord and its agents may enter the
Premises at any time in case of emergency and shall have the right to use any
and all means which Landlord may reasonably deem proper to open such doors
during an emergency in order to obtain entry to the Premises, provided Landlord
promptly repairs all damages caused thereto. Any entry to the Premises obtained
by Landlord in the event of an emergency shall not, under any circumstances, be
construed or deemed to be a forcible or unlawful entry into, or detainer of, the
Premises, or to be an eviction of Tenant from the Premises or any portion
thereof.

      SECTION 7.3 EXHIBITION OF PREMISES. Tenant shall permit Landlord and its
agents, upon not less than twenty four hours' (24) notice, to enter and pass
through the Premises or any part thereof at

                                       13
<PAGE>   14
reasonable times during normal business hours to: (a) post notices of
non-responsibility; (b) exhibit the Premises to holders of encumbrances on the
interest of Landlord under the Lease and to prospective purchasers or mortgagees
of the Office Complex; and (c) during the period of six (6) months prior to the
expiration of the Lease Term, exhibit the Premises to prospective tenants
thereof. In addition, Landlord may post commercially reasonable signage
indicating that the Premises will be available for occupancy. If during the last
month of the Lease Term, Tenant shall have removed substantially all of Tenant's
property and personnel from the Premises, Landlord may, after obtaining the
consent of Tenant and satisfying such reasonable insurance obligations and
indemnification requirements as Tenant may impose, enter the Premises and
repair, alter, and redecorate the same, without abatement of Rent and without
liability to Tenant; and such acts shall have no effect on this Lease.

      SECTION 7.4 RIGHT OF LANDLORD TO PERFORM. All covenants and agreements to
be performed by Tenant under any of the terms of this Lease shall be performed
by Tenant at Tenant's sole cost and expense and without any abatement of Rent.
If Tenant shall fail to pay any sum of money (other than Rent due Landlord)
required to be paid by it hereunder or shall fail to perform any other act on
its part to be performed hereunder, and such failure shall continue for five (5)
days following receipt of detailed notice from Landlord including, but not
limited to, the failure to commence and complete repairs promptly and
adequately, and the failure to remove any liens or otherwise to perform any act
or fulfill any obligation required of Tenant under this Lease, Landlord may, but
shall not be obligated to, and without waiving or releasing Tenant from any
obligations of Tenant, make any such payment or perform any such act on Tenant's
part to be made or performed as in this Lease provided. Notwithstanding the
foregoing, Landlord shall not be required to give Tenant written notice prior to
performing on Tenant's behalf in the event of an emergency. All sums so paid by
Landlord and all necessary incidental costs, together with an administrative
overhead charge equal to twenty percent (20%) of the actual costs incurred,
shall be payable to Landlord by Tenant as Rent on demand and Tenant covenants to
pay all such sums. Landlord shall have (in addition to any other right or remedy
of Landlord) the same rights and remedies in the event of Tenant's nonpayment of
such sums, as in the case of default by Tenant in the payment of Rent to
Landlord. Notwithstanding the foregoing, except in the case of an emergency,
Landlord agrees not to perform for Tenant's account until the expiration of all
applicable notice and cure periods referenced in this Lease.

                                  ARTICLE 8
                         ALTERATIONS AND IMPROVEMENTS

      SECTION 8.1 TENANT'S CHANGES AND ALTERATIONS. Tenant shall have the right
at any time, and from time to time during the term of this Lease, to make such
changes and alterations, structural or otherwise, to the Premises, improvements
and fixtures hereafter erected on the Premises as Tenant shall deem necessary or
desirable in connection with the requirements of its business, which changes and
alterations (other than changes or alterations of Tenant's movable trade
fixtures and equipment) shall be made in all cases subject to the following
conditions, which Tenant covenants to observe and perform:

  (a) PERMITS. No change or alteration shall be undertaken until Tenant shall
      have procured and paid for, so far as the same may be required by the
      applicable governmental authorities from time to time, all municipal,
      state and federal permits and authorizations of the various governmental
      bodies and departments having jurisdiction thereof, and Landlord agrees to
      join in the application for such permits or authorizations whenever such
      action is necessary, all at Tenant's sole cost and expense.

  (b) COMPLIANCE WITH PLANS AND SPECIFICATIONS. Before commencement of any
      change, alteration, restoration or construction (hereinafter sometimes
      referred to as "Work") involving in the aggregate an estimated cost of
      more than $10,000 or which would materially alter the mechanical,
      structural, or electrical systems of the Building, Tenant shall (i)
      furnish Landlord with detailed plans and specifications of the proposed
      change or alteration; (ii) obtain Landlord's prior written consent, which
      consent shall not be unreasonably withheld; (iii) provide Landlord with
      the name of the licensed architect or licensed professional engineer
      selected and paid for by Tenant, who shall supervise any such work
      (hereinafter referred to as "Alterations Architect or Engineer"); and (iv)
      obtain Landlord's prior written approval of detailed plans and
      specifications prepared and

                                       14
<PAGE>   15
approved in writing by said Alterations Architect or Engineer, and of each
amendment and change thereto.

  (c) VALUE MAINTAINED. Any change or alteration shall, when completed, be of
      such character as not to reduce the value of the Premises or the Building
      to which such change or alteration is made below its value immediately
      before such change or alteration, nor shall such change or alteration
      reduce the area or cubic content of the Building, nor change the Building
      as to use without Landlord's e xpress written consent. Tenant further
      agrees that in no event shall any change or alteration void or impair any
      of Landlord's warranties on the Building and, to the extent same are
      voided or impaired, Landlord's corresponding warranties to Tenant as
      contained in this Lease shall be likewise voided.

 (d)  COMPLIANCE WITH LAWS. All Work done in connection with any change or
      alteration shall be done promptly and in a good and workmanlike manner and
      in compliance with all building and zoning laws of the place in which the
      Premises are situated, and with all laws, ordinances, orders, rules,
      regulations and requirements of all federal, state and municipal
      governments and appropriate departments, commissions, boards and officers
      thereof, and in accordance with the orders, rules and regulations of the
      Board of Fire Underwriters where the Premises are located, or any other
      body exercising similar functions. The cost of any such change or
      alteration shall be paid so that the Premises and all portions thereof
      shall at all times be free of liens for labor and materials supplied to
      the Premises, or any portion thereof. The Work of any change or alteration
      shall be prosecuted with reasonable dispatch, delays due to strikes,
      lockouts, acts of God, inability to obtain labor or materials,
      governmental restrictions or similar causes beyond the control of Tenant
      excepted. Tenant shall obtain and maintain, or cause to be obtained and
      maintained, at no expense to Landlord, during the performance of the Work,
      workers' compensation insurance in normal and customary amounts, covering
      all persons employed in connection with the Work and with respect to which
      death or injury claims could be asserted against Landlord or Tenant or
      against the Premises or any interest therein. Tenant shall also cause any
      contractor performing work on Tenant's behalf to carry and maintain, at no
      expense to Landlord, a non-deductible comprehensive general liability
      insurance policy, which shall include contractor's liability coverage,
      contractual liability coverage, completed operations coverage, a broad
      form property damage endorsement and contractor's protective liability
      coverage to afford protection with limits, for each occurrence, of not
      less than Three Million Dollars ($3,000,000) combined single limit,
      written on an occurrence basis. In addition, the fire insurance with
      "extended coverage" endorsement required by Section 6.1 hereof shall be
      supplemented with "builder's risk" insurance on a completed value form or
      other comparable coverage on the Work. All such insurance shall be in a
      company or companies authorized to do business in the state in which the
      Premises are located and reasonably satisfactory to Landlord, and all such
      policies of insurance or, at Tenant's option, certificates of insurance
      shall be delivered to Landlord endorsed "Premium Paid" by the company or
      agency issuing the same, or with other evidence of payment of the premium
      satisfactory to Landlord.

  (e) PROPERTY OF LANDLORD. Unless otherwise designated by Tenant at the time
      Landlord's consent is obtained, all improvements and alterations (other
      than Tenant's movable trade fixtures and equipment) made or installed by
      Tenant shall immediately, upon completion or installation thereof, become
      the property of Landlord without payment therefor by Landlord, and shall
      be surrendered to Landlord on the expiration of the term of this Lease.

  (f) LOCATION OF IMPROVEMENTS. No change, alteration, restoration or new
      construction shall be in or connect the Premises with any property,
      building or other improvement located outside the boundaries of the Land,
      nor shall the same obstruct or interfere with any existing easement.

  (g) REMOVAL OF IMPROVEMENTS. As a condition to granting approval for any
      changes or alterations Landlord, by written notice to Tenant, given at or
      prior to the time of granting

                                       15
<PAGE>   16
such approval, may require Tenant to remove any improvements, additions or
installations installed by Tenant in the Premises at Tenant's sole cost and
expense, and repair and restore any damage caused by the installation and
removal of such improvements, additions, or installations; provided, however,
the only improvements, additions or installations which Tenant shall remove
shall be those specified in such notice. All improvements, additions or
installations installed by Tenant which did not require Landlord's prior
approval shall be removed by Tenant as provided for in this Section 8.1(g),
unless Tenant has obtained a written waiver of such condition from Landlord.

  (h) WRITTEN NOTIFICATION REQUIRED. Tenant shall notify Landlord in writing ten
      (10) days prior to commencing any alterations, additions or improvements
      to the Premises which have been approved by Landlord so that Landlord
      shall have the right to record and post notices of non-responsibility on
      the Premises.

      SECTION 8.2 NONSTRUCTURAL ALTERATIONS/WITHOUT LANDLORD'S CONSENT.
Notwithstanding the foregoing, Tenant shall have the right from time to time and
at any time, without Landlord's consent, to perform the following work within
the Premises: (i) install, remove and relocate nonstructural office partitioning
provided such work does not materially and adversely affect the base building
structure or HVAC systems, (ii) paint and install wall coverings, (iii) install
and remove office furniture, (iv) relocate electrical outlets, (v) install and
remove workstations, (vi) install and remove Tenant's equipment and perform
cable pulls in connection therewith, and (vii) install and remove carpeting and
other floor coverings.

      SECTION 8.3 FREEDOM FROM LIENS. Tenant shall not suffer or permit any
mechanic's lien or other lien to be filed against the Office Complex, or any
portion thereof, by reason of work labor, skill, services, equipment or
materials supplied or claimed to have been supplied to the Office Complex at the
request of Tenant, or anyone holding the Premises, or any portion thereof,
through or under Tenant. If any such mechanic's lien or other lien shall at any
time be filed against the Office Complex, or any portion thereof, Tenant shall
cause the same to be discharged of record or satisfied by bonding within 30 days
of the date of filing the same. If Tenant shall fail to discharge or bond off
such mechanic's lien or liens or other lien within such period, then, in
addition to any other right or remedy of Landlord, after five (5) days prior
written notice to Tenant, Landlord may, but shall not be obligated to, discharge
the same by paying to the claimant the amount claimed to be due or by procuring
the discharge of such lien as to the Office Complex by deposit in the court
having jurisdiction of such lien, the foreclosure thereof or other proceedings
with respect thereto, of a cash sum sufficient to secure the discharge of the
same, or by the deposit of a bond or other security with such court sufficient
in form, content and amount to procure the discharge of such lien, or in such
other manner having reasonable cost as is now or may in the future be provided
by present or future law for the discharge of such lien as a lien against the
Office Complex. Such amount paid by Landlord, or the value of such deposit so
made by Landlord, together with all reasonable costs, fees and expenses in
connection therewith (including reasonable attorney's fees of Landlord),
together with interest thereon at the Default Rate, shall be repaid by Tenant to
Landlord within thirty (30) days following demand by Landlord and if unpaid may
be treated as Additional Rent. Tenant shall indemnify and defend Landlord
against and save Landlord and the Office Complex, and any portion thereof,
harmless from all losses, costs, damages, expenses, liabilities, suits,
penalties, claims, demands and obligations, including, without limitation,
reasonable attorney's fees resulting from the assertion, filing, foreclosure or
other legal proceedings with respect to any such mechanic's lien or other lien.

      Tenant shall specifically notify all materialmen, contractors, artisans,
mechanics, laborers and any other person now or hereafter furnishing any labor,
services, materials, supplies or equipment to Tenant with respect to the Office
Complex, or any portion thereof, that they must look exclusively to Tenant to
obtain payment for the same, and that Landlord shall not be liable for any
labor, services, materials, supplies, skill, machinery, fixtures or equipment
furnished or to be furnished to Tenant upon credit, and that no mechanic's lien
or other lien for any such labor, services, materials, supplies, machinery,
fixtures or equipment shall attach to or affect the estate or interest of
Landlord in and to the Office Complex, or any portion thereof.

      SECTION 8.4 LANDLORD'S INDEMNIFICATION. The provisions of Section 8.3
above shall not apply to any mechanic's lien or other lien for labor, services,
materials, supplies, machinery, fixtures or

                                       16
<PAGE>   17
equipment furnished to the Office Complex in the performance of Landlord's
obligations to construct required by the Work Agreement, and Landlord does
hereby agree to indemnify and defend Tenant against and save Tenant and the
Office Complex, and any portion thereof, harmless from all losses, costs,
damages, expenses, liabilities, suits, penalties, claims, demands and
obligations, including, without limitation, reasonable attorney's fees resulting
from the assertion, filing, foreclosure or other legal proceedings with respect
to any such mechanic's lien or other lien.

      SECTION 8.5 REMOVAL OF LIENS. Except as otherwise provided for in this
Article 8, Tenant shall not create, permit or suffer, and shall promptly
discharge and satisfy of record, any other lien, encumbrance, charge, security
interest, or other right or interest which shall be or become a lien,
encumbrance, charge or security interest upon the Office Complex, or any portion
thereof, or the income therefrom, or on the interest of Landlord or Tenant in
the Office Complex, or any portion thereof, save and except for those liens,
encumbrances, charges, security interests, or other rights or interests
consented to, in writing, by Landlord, or those mortgages, assignments of rents,
assignments of leases and other mortgage documentation placed thereon by
Landlord in financing or refinancing the Office Complex.

                                  ARTICLE 9
                                   REPAIRS

      SECTION 9.1 TENANT'S REPAIR OBLIGATIONS. Subject to Article 6 hereof, and
except to the extent the responsibility of Landlord hereunder, Tenant shall,
during the term of this Lease, at Tenant's expense, keep the non-structural
elements of the Building and all changes and alterations made by Tenant to the
Building (whether non-structural or structural) in as good order, condition and
repair as they were at the time Tenant took possession of the same, reasonable
wear and tear and damage from fire and other casualties excepted. Tenant shall
keep the Premises in a neat and sanitary condition and shall not commit any
nuisance or waste on the Premises or in, on, or about the Office Complex or
throw foreign substances in the plumbing facilities. All uninsured damage or
injury to the Premises, or to the Office Complex caused by Tenant moving
furniture, fixtures, equipment, or other devices in or out of the Premises or
Office Complex or by installation or removal of furniture, fixtures, equipment,
devices or other property of Tenant, its agents, contractors, servants or
employees, due to carelessness, omission, neglect, improper conduct, or other
cause of Tenant, its servants, employees, agents, visitors, or licensees, shall
be repaired, restored and replaced promptly by Tenant at its sole cost and
expense to the reasonable satisfaction of Landlord. All repairs, restorations
and replacements shall be in quality and class equal to the original work and
shall comply with all requirements of the Lease.

      SECTION 9.2 LANDLORD'S INSPECTION. Intentionally Deleted.

      SECTION 9.3 JOINT INSPECTION UPON VACATION. Tenant shall give written
notice to Landlord at least thirty (30) days prior to vacating the Premises for
the express purpose of arranging a meeting with Landlord for a joint inspection
of the Premises. In the event of Tenant's failure to give such notice and
arrange such joint inspection, Landlord's inspection at or after Tenant's
vacation of the Premises shall be conclusively deemed correct for purposes of
determining Tenant's responsibility for repairs and restoration hereunder.

                                  ARTICLE 10
                          ASSIGNMENT AND SUBLETTING

      SECTION 10.1 RESTRICTION ON TRANSFER. Tenant shall not sublet the
Premises, or any portion thereof, nor assign, mortgage, pledge, transfer or
otherwise encumber or dispose of this Lease, or any interest therein, or in any
manner assign, mortgage, pledge, transfer or otherwise encumber or dispose of
its interest or estate in the Premises, or any portion thereof, without
obtaining Landlord's prior written consent in each and every instance, which
consent shall not be unreasonably withheld or delayed, provided the following
conditions are complied with:

  (a) Any assignment of this Lease (but specifically excluding any sublease)
      shall transfer to the assignee all of Tenant's right, title and interest
      in this Lease and all of Tenant's estate or interest in the Premises.

                                       17
<PAGE>   18
  (b) At the time of any assignment or subletting, and at the time when Tenant
      requests Landlord's written consent thereto, this Lease must be in full
      force and effect, without any breach or default thereunder on the part of
      Tenant beyond any applicable notice and cure period.

 (c) Any such assignee (but specifically excluding any sublessee) shall assume,
      by written, recordable instrument, in form and content reasonably
      satisfactory to Landlord and such assignee, the due performance of all of
      Tenant's obligations under this Lease, and such assumption agreement shall
      state that the same is made by the assignee for the express benefit of
      Landlord as a third party beneficiary thereof. A copy of the assignment
      and assumption agreement, both in form and content reasonably satisfactory
      to Landlord, fully executed and acknowledged by assignee, together with a
      certified copy of a properly executed corporate resolution (if the
      assignee be a corporation) authorizing the execution and delivery of such
      assumption agreement, shall be sent to Landlord ten (10) days prior to the
      effective date of such assignment.

  (d) In the case of a subletting, a copy of any sublease fully executed and
      acknowledged by Tenant and the sublessee shall be mailed to Landlord
      within thirty (30) days following the effective date of such subletting.

  (e) Such assignment or subletting shall be subject to all the provisions,
      terms, covenants and conditions of this Lease (except, in the case of a
      sublease, payment of the Base Rent and Additional Rent due under this
      Lease), and Tenant-assignor (and the guarantor or guarantors of this
      Lease, if any) and the assignee or assignees shall continue to be and
      remain liable under this Lease.

 (f) Each sublease permitted under this Section 10.1 shall contain provisions to
      the effect that (i) such sublease is only for the use and occupancy by the
      sublessee and not any other third party; (ii) such sublease is subject and
      subordinate to all of the terms, covenants and conditions of this Lease
      and to all of the rights of Landlord thereunder; and (iii) in the event
      this Lease shall terminate before the expiration of such sublease, the
      sublessee thereunder will, provided Landlord and its lender(s) recognizes
      such sublessee's rights under the sublease and agrees not to disturb
      Tenant's occupancy and possession so long as Tenant is not in default
      thereunder, attorn to Landlord and waive any rights the sublessee may have
      to terminate the sublease or to surrender possession thereunder, as a
      result of the termination of this Lease. Landlord agrees to enter into a
      Subordination, Non-Disturbance and Attornment Agreement ("SNDA") with the
      subtenants, the substance of which shall be substantially similar to the
      SNDA attached as Exhibit C, and Landlord agrees to use its best
      commercially reasonable efforts to obtain such an SNDA from Landlord's
      Mortgagee(s) (as defined in Section 15.3 hereof) for the benefit of the
      subtenants.

  (g) Tenant agrees to pay on behalf of Landlord any and all reasonable, actual
      out-of-pocket costs of Landlord, including reasonable attorney's fees
      actually paid or payable to outside counsel, occasioned by such assignment
      or subletting. Landlord agrees to use good faith efforts to minimize the
      fees of outside counsel.

      For purposes of this Lease, any transfer of less than fifty percent (50%)
in the aggregate of stock membership interest or partnership interest in Tenant
shall not constitute an assignment.

      Notwithstanding the terms of this Section 10.1, Tenant may sublet up to
seventy percent (70%) of the square footage contained in the Building in the
aggregate without Landlord's prior written consent, provided (i) every such
sublease shall be subject to the conditions contained in sections 10.1 (b), (d),
(e), (f) and (g) above, and (ii) any sublessee shall be of a type and quality
consistent with a first class office building. Tenant shall be entitled to erect
commercially reasonable signage on the Property signifying that space in the
Building is available for sublease, such signage to be in compliance with all
Legal Requirements, recorded covenants and restrictions and the like governing
the Property. In addition, Tenant may, without Landlord's prior written consent,
(a) sublet all or a portion of the Premises to any related corporation or entity
which controls Tenant, is controlled by Tenant or is under common control

                                       18
<PAGE>   19
with Tenant; or (b) assign this Lease to a successor corporation into which or
with which Tenant is merged or consolidated or which acquires substantially all
of Tenant's assets and property; provided that (i) in the case of an assignment,
such successor entity assumes all of the obligations and liabilities of Tenant,
(ii) in the case of an assignment or a sublease, such successor entity's net
worth indicates that the entity has similar financial capability as Tenant and
the ability to meet the obligations herein, and (iii) such subletting or
assignment does not violate the terms of any deeds of trust encumbering the
Building of which Tenant has been provided notice.

      SECTION 10.2 RESTRICTION FROM FURTHER ASSIGNMENT. Any further assignment
or subleasing shall be governed by the terms of this Article 10. No assignment
or subleasing shall relieve Tenant from any of Tenant's obligations set forth in
this Lease.

      SECTION 10.3 LANDLORD'S TERMINATION RIGHTS. Intentionally Deleted.

      SECTION 10.4 TENANT'S FAILURE TO COMPLY. Tenant's failure to comply with
all of the foregoing provisions and conditions of this Article 10 shall (whether
or not Landlord's consent is required under this Article), at Landlord's option,
render any purported assignment or subletting null and void and of no force and
effect. Notwithstanding the foregoing, in the event Landlord receives written
notice of Tenant's failure to comply with the terms of this Article 10, then if
Landlord desires to exercise its right to render the applicable sublease and/or
assignment null and void, Landlord must do so within sixty (60) days of the date
of receipt of such notice.

      SECTION 10.5 SHARING OF EXCESS RENT. If Landlord consents to Tenant
assigning its interest under this Lease or subletting all or any portion of the
Premises, Tenant shall pay to Landlord (in addition to Rent and all other
amounts payable by Tenant under this Lease) 50% of the rents and other
considerations payable by such assignee or subtenant (net of brokerage
commissions, improvement costs, legal fees and other reasonable costs and
expenses incurred in connection with the assignment or subletting) in excess
of the Rent otherwise payable by Tenant from time to time under this Lease. For
the purposes of this computation, the additional amount payable by Tenant shall
be determined by either (i) application of the rental rate per square foot for
the Building or any portion thereof sublet, or (ii) the fair market rental rate
for rooftop space or other space at the Premises sublet, as applicable. Said
additional amount shall be paid to Landlord immediately upon receipt by Tenant
of such Rent or other considerations from the assignee or subtenant.

                                   ARTICLE 11
                        DAMAGE BY FIRE OR OTHER CASUALTY

      SECTION 11.1 TENANTABLE WITHIN 150 DAYS. If fire or other casualty shall
render the whole or any material portion of the Premises untenantable, Landlord
shall obtain an estimate for the time required to rebuild from a reputable
licensed contractor, and shall forward the time estimate to Tenant within thirty
(30) days from the date of such damage or destruction. If, pursuant to the
estimate, the Premises can reasonably be expected to be made tenantable within
one hundred fifty (150) days from the date of such event, then Landlord shall
repair and restore the Premises and the Office Complex within such one hundred
fifty (150) day period. In the event of the foregoing, this Lease shall remain
in full force and effect.

      SECTION 11.2 NOT TENANTABLE WITHIN 150 DAYS. If, pursuant to the time
estimate referenced in Section 11.1 above, the Premises cannot reasonably be
expected to be made tenantable within one hundred (150) days from the date of
the casualty event, then Tenant may, by written notice to Landlord within thirty
(30) days from the date of Landlord's time estimate, terminate this Lease.
Tenant's termination notice shall state a termination date which shall be at
least thirty (30) days but no more than sixty (60) days from the date of the
termination notice.

      SECTION 11.3 DAMAGE OCCURRING AT END OF TERM. Notwithstanding the terms of
Sections 11.1 and 11.2 above, in the event the Premises are damaged during the
last twenty-four (24) months of the initial term to the extent of twenty-five
percent (25%) or more of the replacement cost thereof, Landlord or Tenant may
terminate this Lease by giving written notice of such termination to the other

                                       19
<PAGE>   20
party within sixty (60) days of the date of the casualty. The termination notice
shall specify a termination date at least thirty (30) days but not more than
sixty (60) days after the date of such notice.

      Notwithstanding anything to the contrary contained in this Section 11.3,
Tenant shall be entitled to nullify Landlord's termination notice by delivering
to Landlord written notice ("Renewal Notice") of Tenant's exercise of any then
outstanding renewal options granted to Tenant pursuant to Section 16.32 of this
Lease. The Renewal Notice shall be delivered within thirty (30) days of the date
of Landlord's termination notice.

      SECTION 11.4 UNINSURED CASUALTY. If an uninsured casualty event shall
render any portion of the Premises or any material portion of the Office Complex
untenantable, then so long as Landlord shall have had in effect all insurance
required by the terms of this Lease, Landlord may, by notice to Tenant, mailed
within thirty (30) days from the date of such damages or destruction, terminate
this Lease effective upon a date within thirty (30) days from the date of such
notice.

      SECTION 11.5 DEDUCTIBLE PAYMENTS. If the Premises or the Office Complex is
damaged, and such damage is of the type insured against under the fire and
special form property damage insurance required to be maintained by Landlord
hereunder, the cost of repairing said damage up to the amount of the deductible
under said insurance policy shall be included as a part of the Operating
Expenses. If the damage is not covered by such insurance policies and Landlord
elects to repair the damage, then Tenant shall pay Landlord the "deductible
amount" (if any) under Landlord's insurance policies, and, if the damage was
directly and exclusively caused by an act or omission of Tenant, the difference
between the actual cost of repair and any insurance proceeds received by
Landlord.

      SECTION 11.6 LANDLORD'S REPAIR OBLIGATIONS. If fire or other casualty
shall render the whole or any material part of the Premises untenantable and
neither Landlord nor Tenant terminates this Lease pursuant to its rights herein,
then Landlord shall repair and restore the Premises and the Office Complex to as
near their condition prior to the fire or other casualty as is reasonably
possible with all due diligence and speed and within the applicable time period
required by this Article 11 (subject to delays for causes beyond Landlord's
reasonable control) and the Rent for the period during which the Premises are
untenantable shall be equitably abated (based upon the portion of the Premises
which is untenantable). In no event shall Landlord be obligated to repair or
restore any special equipment or improvements installed by Tenant at Tenant's
expense.

      SECTION 11.7 RENT APPORTIONMENT. In the event of a termination of this
Lease pursuant to this Article 11, Rent shall be apportioned on a per diem basis
and paid to the date of the Lease termination.

      SECTION 11.8 INSURANCE TRUSTEE. If Landlord fails to comply with its
obligation to rebuild the Premises pursuant to this Article 11 and Tenant elects
to exercise its self-help rights as set forth in Section 14.7 hereof, upon
receipt of written instructions from Tenant, Landlord shall inform its insurance
company that Tenant has undertaken the rebuilding of the Premises and all
insurance proceeds shall thereafter be placed with an insurance trustee and
disbursed upon terms and conditions similar to those contained in an industry
standard construction loan agreement.

                                  ARTICLE 12
                                EMINENT DOMAIN

      SECTION 12.1 TENANT'S TERMINATION. If the whole of or a substantial part
of the Premises is taken by any public authority under the power of eminent
domain, or taken in any manner for any public or quasi-public use, so as to
render (in Tenant's reasonable judgment) the remaining portion of the Premises
unsuitable for the purposes intended hereunder, then Tenant shall give Landlord
written notice within thirty (30) days of receiving notice of the taking and the
term of this Lease shall cease as of the day possession shall be taken by such
public authority and Landlord shall make a pro rata refund of any prepaid rent.
Subject to Section 12.2, all damages awarded for such taking under the power of
eminent domain or any like proceedings shall belong to and be the property of
Landlord, Tenant hereby assigning to Landlord its interest, if any, in said
award. Further, if all or any material part of the Office Complex is taken by
public authority under the power of eminent domain, or taken in any manner for
any public or

                                       20
<PAGE>   21
quasi-public use, so as to render any remaining portion of the Premises
unsuitable in Tenant's reasonable opinion, for the purposes intended hereunder,
upon delivery of possession to the condemning authority pursuant to the
proceedings, Tenant may, at its option, terminate this Lease as to the remainder
of the Premises by written notice to Landlord, such notice to be given to
Landlord within thirty (30) days after Tenant receives notice of the taking.
Tenant shall not have the right to terminate this Lease pursuant to the
preceding sentence unless the business of Tenant cannot in Tenant's reasonable
judgment be carried on with substantially the same utility and efficiency in the
remainder of the Premises. Any notice of termination shall specify the date not
more than sixty (60) days after the giving of such notice as the date for such
termination.

      SECTION 12.2 TENANT'S PARTICIPATION. Provisions in this Article 12 to the
contrary notwithstanding, Tenant shall have the right to prove in any
condemnation proceedings and to receive any separate award which may be made for
damages to or condemnation of Tenant's movable trade fixtures and equipment and
for moving expenses; provided, however, Tenant shall in no event have any right
to receive any award for its interest in this Lease or for loss of leasehold.
Provisions in this Article 12 to the contrary notwithstanding, in the event of a
partial condemnation of the Office Complex or the Premises and this Lease is not
terminated, Landlord shall, at its sole cost and expense, promptly restore the
Premises and Office Complex to a complete architectural unit as near as possible
to that condition which existed prior to such partial condemnation and the Base
Rent provided for herein during the period from and after the date of delivery
of possession pursuant to such proceedings to the termination of this Lease
shall be reduced to the fair market rent of the Premises after such taking.

                                  ARTICLE 13
                            SURRENDER OF PREMISES

      SECTION 13.1 SURRENDER OF POSSESSION. On the last day of the term of this
Lease, or on the sooner termination thereof, Tenant shall peaceably surrender
the Premises in good condition and repair consistent with Tenant's duty to make
repairs as herein provided, reasonable wear and tear and casualty loss excluded.
On or before the last day of the term of this Lease, or the date of sooner
termination thereof, Tenant shall, at its sole cost and expense, remove all of
its property and trade fixtures and equipment from the Premises which Tenant is
required to remove pursuant to the terms of this Lease. All property not removed
within ten (10) days following receipt of notice from Landlord shall be deemed
abandoned. Tenant hereby appoints Landlord its agent to remove all abandoned
property of Tenant from the Premises upon termination of this Lease and to cause
its transportation and storage for Tenant's benefit, all at the sole cost and
risk of Tenant and Landlord shall not be liable for damage, theft,
misappropriation or loss thereof and Landlord shall not be liable in any manner
in respect thereto. Tenant shall pay all reasonable costs and expenses of such
removal, transportation and storage.

      Tenant shall reimburse Landlord upon demand for any reasonable expenses
incurred by Landlord with respect to removal, transportation, or storage of
abandoned property and with respect to restoring said Premises to good order,
condition and repair. All alterations, additions and fixtures, other than those
which Tenant may, or is required to, remove pursuant to the terms of this Lease,
shall remain the property of Landlord and shall be surrendered with the Premises
as a part thereof. Tenant shall promptly surrender all keys for the Premises to
Landlord at the place then fixed for the payment of rent and shall inform
Landlord of combinations on any vaults, locks and safes left on the Premises.
Notwithstanding any provision to the contrary contained herein, in no event
shall Tenant be liable for, or otherwise be obligated to pay, lost actual or
potential profits or any other damages of a consequential, speculative, special,
punitive or similar nature.

      SECTION 13.2 TENANT RETAINING POSSESSION. In the event Tenant remains in
possession of the Premises after expiration of this Lease, and without the
execution of a new lease, but with Landlord's written consent, it shall be
deemed to be occupying the Premises as a tenant from month to month, subject to
all the provisions, conditions and obligations of this Lease insofar as the same
can be applicable to a month-to-month tenancy, except that the Base Rent shall
be 150% of the then current Base Rent for the Premises. In the event Tenant
remains in possession of the Premises after expiration of this Lease and without
the execution of a new lease and without Landlord's written consent, Tenant
shall be deemed to be occupying the Premises without claim of right and Tenant
shall pay a charge for each day of occupancy an amount equal to double the Base
Rent and Additional Rent (on a daily basis) then due under this Lease.
Notwithstanding any provision to the contrary contained herein, in no event
shall Tenant be liable

                                       21
<PAGE>   22
for, or otherwise be obligated to pay, lost actual or potential profits or any
other damages of a consequential, speculative, special, punitive or similar
nature.

                                  ARTICLE 14
                              DEFAULT OF TENANT

      SECTION 14.1 EVENTS OF DEFAULT. The occurrence of any one or more of the
following events (in this Article sometimes called "Event of Default") shall
constitute a default and breach of this Lease by Tenant:

      (a) If Tenant fails to pay any Base Rent or Additional Rent payable under
this Lease or fails to pay any obligation required to be paid by Tenant when and
as the same shall become due and payable, and such default continues for a
period often (10) days after receipt of written notice thereof given by Landlord
to Tenant.

      (b) If Tenant fails to perform any of Tenant's nonmonetary obligations
under this Lease for a period of thirty (30) days after receipt of written
notice from Landlord; provided that if more time is required to complete such
performance, Tenant shall not be in default if Tenant commences such performance
within the thirty (30) day period and thereafter diligently pursues its
completion within ninety (90) days. However, Landlord shall not be required to
give such notice if Tenant's failure to perform constitutes a non-curable breach
of this Lease. The notice required by this subsection is intended to satisfy any
and all notice requirements imposed by law on Landlord and is not in addition to
any such requirement.

      (c) If Tenant, by operation of law or otherwise, violates the provisions
of Article 10 hereof relating to assignment, sublease, mortgage or other
transfer of Tenant's interest in this Lease or in the Premises and such
violation continues for five (5) days after written notice from Landlord.

      (d) If default shall be made by Tenant in keeping, observing or performing
any of the terms contained in this Lease, other then those referred to in
Subparagraphs (a) and (c) of this Section 14.1, and such default will result in
Landlord being subject to criminal liability, and such default shall continue
after written notice thereof given by Landlord to Tenant, and Tenant fails to
thereafter proceed timely and promptly with all due diligence and in good faith
to cure the same and thereafter to prosecute the curing of such default with all
due diligence, it being intended that in connection with a default which exposes
Landlord to criminal liability that Tenant shall proceed immediately to cure or
correct such condition with continuity and with all due diligence and in good
faith.

      SECTION 14.2 LANDLORD'S REMEDIES. Upon the occurrence of an Event of
Default by Tenant, and at any time thereafter, with or without notice or demand
and without limiting Landlord in the exercise of any right or remedy which
Landlord may have, Landlord shall be entitled to the rights and remedies set
forth below.

      (a) TERMINATION OF POSSESSION. Terminate Tenant's right to possession of
the Premises by any lawful means, in which case the Lease shall terminate and
Tenant shall immediately surrender possession of the Premises to Landlord. In
such event, Landlord shall have the immediate right to reenter and remove all
persons and property, and such property may be removed and stored in a public
warehouse or elsewhere at the cost of, and for the account of Tenant, all
without service of notice or resort to legal process and without being deemed
guilty of trespass, or becoming liable for any loss or damage which may be
occasioned thereby, except for Landlord's gross negligence or willful
misconduct. In the event that Landlord shall elect to so terminate this Lease,
then Landlord shall be entitled to recover from Tenant all damages incurred by
Landlord by reason of Tenant's default, including:

           (i) The equivalent of the amount of the Base Rent and Additional Rent
which would be payable under this Lease by Tenant if this Lease were still in
effect, less

           (ii) The net proceeds of any commercially reasonable reletting
affected pursuant to the provisions of Section 14.2 hereof after deducting all
of Landlord's reasonable expenses in connection with such reletting, including,
without limitation, all repossession costs, brokerage commissions, legal

                                       22
<PAGE>   23
expenses, reasonable attorneys' fees, alteration costs, and expenses of
preparation of the Premises, or any portion thereof, for such reletting.

           Tenant shall pay such current damages in the amount determined in
accordance with the terms of this Section 14.2 as set forth in a written
statement thereof from Landlord to Tenant (hereinafter caged the "Deficiency"),
to Landlord in monthly installments on the days on which the Rent would have
been payable under this Lease if this Lease were still in effect, and Landlord
shall be entitled to recover from Tenant each monthly installment of the
Deficiency as the same shall arise.

      (b) DAMAGES. At any time after an Event of Default and termination of this
Lease, whether or not Landlord shall have collected any monthly Deficiency as
set forth in Section 14.2, Landlord shall be entitled to recover from Tenant, in
lieu of continuing monthly payments for the Deficiency, and Tenant shall pay to
Landlord, on demand, as and for final damages for Tenant's default, an amount
equal to the difference between the then present worth of the aggregate of the
Base Rent and Additional Rent and any other charges to be paid by Tenant
hereunder for the remainder of the temm of this Lease, and the then present
worth of the then aggregate fair and reasonable fair market rent of the Premises
for the same period, net of the costs and expenses referenced in Section
14.2(a)(ii). In the computation of present worth, a discount at the rate of nine
percent (9%) per annum shall be employed. If the Premises, or any portion
thereof, shall be relet by Landlord on commercially reasonable temms for the
unexpired term of this Lease, or any part thereof, before presentation of proof
of such damages to any court, commission or tribunal, the amount of Rent
reserved upon such reletting shall, prima facie, be the fair and reasonable fair
market rent for the part or the whole of the Premises so relet during the term
of the reletting. Nothing herein contained or contained in Section 14.2 shall
limit or prejudice the right of Landlord to prove for and obtain, as damages by
reason of such expiration or termination, an amount equal to the maximum allowed
by any statute or rule of law in effect at the time when, and governing the
proceedings in which, such damages are to be proved, whether or not such amount
be greater, equal to or less than the amount of the difference referred to
above.

      (c) REENTRY AND REMOVAL. Upon the occurrence of an Event of Default by
Tenant, Landlord shall also have the right, with or without terminating this
Lease, to reenter the Premises to remove all persons and property from the
Premises. Such property may be removed and stored in a public warehouse or
elsewhere at the cost of and for the account of Tenant. If Landlord shall elect
to reenter the Premises, Landlord shall not be liable for, and Tenant shall
indemnify and hold Landlord harmless for, damages by reason of such reentry
except for Landlord's gross negligence or willful misconduct.

      (d) NO TERMINATION; RECOVERY OF RENT. If Landlord does not elect to
terminate this Lease as provided in this Section 14.2, then Landlord may, from
time to time, recover all Rent as it becomes due under this Lease. At any time
thereafter, Landlord may elect to terminate this Lease and to recover damages to
which Landlord is entitled pursuant to this Article 14.

      (e) RELETTING THE PREMISES. In the event that Landlord should elect to
terminate this Lease, Landlord shall use commercially reasonable efforts to
relet the Premises on commercially reasonable terms, in which event it may
execute any new lease in its own name. Tenant hereunder shall have no right or
authority whatsoever to collect any Rent from such tenant. The proceeds of any
such reletting shall be applied as follows:

           (i) First, to the payment of any indebtedness other than Rent due
hereunder from Tenant to Landlord, including but not limited to reasonable
storage charges or reasonable brokerage commissions owing from Tenant to
Landlord as the result of such reletting;

           (ii) Second, to the payment of the reasonable costs and expenses of
reletting the Premises, including alterations and repairs which Landlord, in its
sole discretion, reasonably deems necessary in connection with such re-letting
and reasonable attorneys' fees incurred by Landlord in connection with the
retaking of the said Premises and such reletting;

           (iii) Third, to the payment of Rent and other charges due and unpaid
hereunder; and

                                       23
<PAGE>   24
           (iv) Fourth, to the payment of future Rent and other damages payable
by Tenant under this Lease.

      The parties hereto shall, and they hereby do, waive trial by jury in any
action, proceeding, or counterclaim brought by either of the parties hereto
against the other on any matters whatsoever arising out of, or in any way
connected with, this Lease, the relationship of Landlord and Tenant, Tenant's
use or occupancy of the Premises and/or Office Complex, and/or claim or injury
or damage. In the event Landlord commences any proceeding to enforce this Lease
or the Landlord/Tenant relationship between the parties or for nonpayment of
Rent (of any nature whatsoever) or additional monies due Landlord from Tenant
under this Lease, Tenant will not interpose any counterclaim of whatever nature
or description in any such proceedings. In the event Tenant must, because of
applicable court rules, interpose any counterclaim or other claim against
Landlord in such proceedings, Landlord and Tenant covenant and agree that, in
addition to any other lawful remedy of Landlord, upon motion of Landlord, such
counterclaim or other claim asserted by Landlord shall be severed out of the
proceeding instituted by Landlord (and, if necessary, transferred to a court of
different jurisdiction), and the proceedings, instituted by Landlord may proceed
to final judgment separately and apart from and without consolidation with or
reference to the status of each counterclaim or any other claim asserted by
Tenant.

      SECTION 14.3 WRITTEN NOTICE OF TERMINATION REQUIRED. Landlord shall not be
deemed to have terminated this Lease and the Tenant's right to possession of the
leasehold or the liability of Tenant to pay Rent thereafter to accrue or its
liability for damages under any of the provisions hereof, unless Landlord shall
have notified Tenant in writing that it has so elected to terminate this Lease.
Tenant covenants that the service by Landlord of any notice pursuant to the
applicable unlawful detainer statutes of the state in which the Office Complex
is located and the Tenant's surrender of possession pursuant to such notice
shall not (unless Landlord elects to the contrary at the time of, or at any time
subsequent to the service of, such notice, and such election be evidenced by a
written notice to Tenant) be deemed to be a termination of this Lease or of
Tenant's right to possession thereof.

      SECTION 14.4 REMEDIES CUMULATIVE; NO WAIVER. All rights, options and
remedies of Landlord contained in this Lease shall be construed and held to be
cumulative, and no one of them shall be exclusive of the other, and Landlord
shall have the right to pursue any one or all of such remedies or any other
remedy or relief which may be provided at law or in equity whether or not stated
in this Lease, including, without limitation, the right of self help, but
subject to all applicable provisions of this Lease.

      No waiver by Landlord or Tenant ("Waiving Party") of a breach of any of
the terms, covenants or conditions of this Lease by the other party ("Breaching
Party") shall be construed or held to be a waiver of any succeeding or preceding
breach of the same or any other term, covenant or condition therein contained.
No waiver of any default of the Breaching Party hereunder shall be implied from
any omission by the Waiving Party to take any action on account of such default
if such default persists or is repeated, and no express waiver shall affect
default other than as specified in said waiver. The consent or approval by the
Waiving Party to or of any act by the Breaching Party requiring the Waiving
Party's consent or approval shall not be deemed to waive or render unnecessary
the Waiving Party's consent to or approval of any subsequent similar acts by the
Breaching Party.

      SECTION 14.5 LEGAL COSTS. Tenant shall reimburse Landlord, upon demand,
for any costs or expenses incurred by Landlord in connection with any Event of
Default of Tenant under this Lease, whether or not suit is commenced or judgment
entered. Such costs shall include reasonable legal fees and costs incurred for
the negotiation of a settlement, enforcement of rights or otherwise.
Furthermore, if any action for an Event of Default to enforce the provisions of
this Lease is commenced, the court in such action shall award to the party in
whose favor a judgment is entered a reasonable sum as attorneys' fees and costs.
Such attorneys' fees and costs shall be paid by the losing party in such action
at such time as it is no longer subject to appeal. Tenant shall also indemnify
Landlord against and hold Landlord harmless from all costs, expenses, demands
and liability incurred by Landlord if Landlord becomes or is made a party to any
claim or action (a) instituted by Tenant, or by any third party against Tenant;
(b) for foreclosure of any lien for labor or material furnished to or for Tenant
or such other person; (c) otherwise arising out of or resulting from any act or
transaction of Tenant or such other person; or (d) necessary to protect
Landlord's interest under this Lease in a bankruptcy proceeding, or other
proceeding under Title 11 of the United States Code, as amended. Tenant shall
defend Landlord against any such claim or action at Tenant's expense with
counsel reasonably acceptable to Landlord or, at Landlord's election, Tenant

                                       24
<PAGE>   25
shall reimburse Landlord for any reasonable legal fees or costs incurred by
Landlord in any such claim or action.

      In addition, Tenant shall pay Landlord's reasonable attorneys' fees
incurred in connection with Tenant's request for Landlord's consent in
connection with any act which Tenant proposes to do and which requires
Landlord's consent.

SECTION 14.6 WAIVER OF DAMAGES FOR REENTRY. Intentionally Deleted.

      SECTION 14.7 TENANT SELF-HELP. Tenant may provide Landlord written notice
if Landlord fails to (i) comply with any of its repair and maintenance
obligations under this Lease, or (ii) comply with its obligations to provide
services under the terms of this Lease, both subject to Unavoidable Delay (as
defined in the Work Agreement). Tenant's written notice shall specify the action
required to be taken, demand that Landlord proceed with such action, and
indicate that Tenant may perform on Landlord's behalf if Landlord fails to
timely respond. Landlord shall, within three (3) days after receipt of such
notice (or immediately after receipt of such notice if Landlord's failure to
comply with its Lease obligations gives rise to an emergency), commence
investigation of the cause of the asserted problem. Landlord shall promptly
commence such repair or replacement, or other action, and diligently pursue
completion thereof. In the event that (x) Landlord fails to respond to Tenant's
notice within the foregoing three (3) day period, or (y) fails to promptly
commence, diligently pursue and ultimately complete same within thirty (30) days
of commencement (or such shorter or longer period of time as is commercially
reasonable under the circumstances) any action set forth in clauses (i) and (ii)
above, then, if the repair, replacement or other action required to be taken
does not affect the structure of the Building and does not affect the
mechanical, electrical, plumbing or other base building systems then, upon
written notice to Landlord, Tenant shall have the right to effect such repair or
replacement, or pursue such other action as may reasonably be necessary in order
to correct the condition. Landlord shall reimburse Tenant on demand for all of
the reasonable costs and expenses incurred by Tenant in connection with such
foregoing remedial activities plus an administrative overhead charge equal to
twenty percent (20%) of the actual cost of repair. Any repair, replacement or
other work performed by Tenant shall be performed in a good and workmanlike
manner and in strict compliance with any Federal, state, local and municipal
laws, rules, regulations and ordinances, and shall be performed by licensed and
bonded contractors carrying customary insurance coverage, which insurance shall
include Landlord as an additional insured. Notwithstanding anything to the
contrary contained herein, no payment by Tenant shall be construed as a waiver
of a default by Landlord under this Section 14.7.

                                  ARTICLE 15
                            SUBORDINATION/ESTOPPEL

      SECTION 15.1 LEASE SUBORDINATE. This Lease shall be subject and
subordinate to any mortgage, deed of trust or ground lease now encumbering the
Premises, the Office Complex, the Property, or any portion thereof by Landlord,
its successors or assigns. The foregoing subordination shall be effective
without the necessity of the execution and delivery of any further instruments
on the part of Tenant to effectuate such subordination. Provided Tenant receives
a non-disturbance agreement substantially in the form attached hereto as Exhibit
C, this Lease shall be further subject and subordinate to any future mortgages,
deeds of trust or ground leases and any amendments, replacements, renewals and
extensions thereof. Tenant agrees at any time hereafter, within fifteen (15)
days following demand, to execute and deliver any instruments, releases, or
other documents that may be reasonably required for the purpose of subjecting
and subordinating this Lease, as above provided, to the lien of any such
mortgage, deed of trust or ground lease, provided such documents shall be
reasonably acceptable to Tenant. It is agreed, nevertheless, that as long as
Tenant is not in default in the payment of Base Rent, Additional Rent, and the
payment of other charges to be paid by Tenant under this Lease, and the
performance of all covenants, agreements and conditions to be performed by
Tenant under this Lease beyond any applicable notice and cure period, then
neither Tenant's right to quiet enjoyment under this Lease, nor the right of
Tenant to continue to occupy the Premises and to conduct its business thereon,
in accordance with the terms of this Lease as against any Landlord, Tenant,
mortgagee, trustee, or their successors or assigns shall be interfered with.

                                       25
<PAGE>   26
      SECTION 15.2 ATTORNMENT. Subject to the terms of this Article 15, in the
event the holder of any mortgage, deed of trust or ground lease shall at any
time elect to have this Lease constitute a prior and superior lien to its
mortgage, deed of trust or ground lease, then, and in such event, upon any such
holder or landlord notifying Tenant to that effect in writing, this Lease shall
be deemed prior and superior in lien to such mortgage, deed of trust, ground
lease, whether this Lease is dated prior or subsequent to the date of such
mortgage, deed of trust or ground lease and Tenant shall execute such attornment
agreement as may be reasonably requested by said holder or landlord, provided
the form and content thereof are reasonably acceptable to Tenant and contain
recognition and non-disturbance covenants satisfactory to Tenant.

      SECTION 15.3 TENANT'S NOTICE OF DEFAULT. Tenant agrees, provided the
mortgagee, ground landlord or trust deed holder under any mortgage, ground
lease, deed of trust or other security instrument ("Mortgagee") shall have
notified Tenant in writing (by the way of a notice of assignment of lease or
otherwise) of its address, Tenant shall give such Mortgagee, simultaneously with
delivery of notice to Landlord, by registered or certified mail, a copy of any
such notice of default served upon Landlord. Tenant further agrees that said
Mortgagee shall have the right to cure any alleged default during the same
period that Landlord has to cure such default.

      SECTION 15.4 ESTOPPEL CERTIFICATES. Landlord and Tenant shall, each
without charge at any time and from time to time, within fifteen (15) days after
written request by the other party, but not more frequently than two (2) times
in any twelve month period, certify, to the extent true, by written instrument,
duly executed, acknowledged and delivered to any mortgagee, assignee of a
mortgagee, proposed mortgagee, or to any purchaser or proposed purchaser, or to
any other person transacting business with Landlord or Tenant and relating to
the Premises:

 (a)  That this Lease (and all guaranties, if any) is unmodified and in full
      force and effect (or, if there have been modifications, that the same is
      in full force and effect, as modified, and stating the modifications);

  (b) The dates to which the Base Rent or Additional Rent have been paid in
      advance;

  (c) Whether or not there are then existing any breaches or defaults by such
      party or the other party known by such party under any of the covenants,
      conditions, provisions, terms or agreements of this Lease, and specifying
      such breach or default, if any, or any setoffs or defenses against the
      enforcement of any covenant, condition, provision, term or agreement of
      this Lease (or of any guaranties) upon the part of Landlord or Tenant (or
      any guarantor), as the case may be, to be performed or complied with (and,
      if so, specifying the same and the steps being taken to remedy the same),
      and

  (d) Such other statements or certificates as Landlord, Tenant or any mortgagee
      may reasonably request.

      It is the intention of the parties hereto that any statement delivered
pursuant to this Section may be relied upon by any of such parties transacting
business with Landlord or Tenant and relating to the Premises. If Landlord or
Tenant does not deliver such statement to the requesting party within such
fifteen (lS) day period, and such failure continues for five (5) additional days
following receipt of a second notice stipulating that such continuing failure
shall have the consequences set forth herein, the requesting party, and any
applicable party transacting business relative to the Premises with the
requesting party, may conclusively presume and rely upon the following facts:
(i) that the terms and provisions of this Lease have not been changed except as
otherwise represented by the requesting party; (ii) that this Lease has not been
canceled or terminated and is in full force and effect, except as otherwise
represented by the requesting party; that the current amount of the Base Rent is
as represented by the requesting party; that there have been no subleases or
assignments of the Lease; (iii) that not more than one month's Base Rent or
other charges have been paid in advance; and (iv) that the requesting party is
not in default under the Lease. In such event, the non-requesting party shall be
estopped from denying the truth of such facts.

                                       26
<PAGE>   27
                                   ARTICLE 16
                                  MISCELLANEOUS

      SECTION 16.1 TIME IS OF THE ESSENCE. Time is of the essence with respect
to the performance of every provision of this Lease in which time of performance
is a factor.

      SECTION 16.2 MEMORANDUM OF LEASE. Upon not less than ten (10) days prior
written request by either party, the parties hereto agree to execute and deliver
to each other a Memorandum Lease, in recordable form, setting forth the
following:

 (a) The date of this Lease;

 (b) The parties to this Lease;

 (c) The term of this Lease;

 (d) The legal description of the Premises; and

 (e) Such other matters reasonably requested by Landlord or Tenant to be stated
     therein.

The cost of recording the memorandum shall be at the expense of the requesting
party.

       SECTION 16.3 JOINT AND SEVERAL LIABILITY. All parties signing this Lease
as Tenant shall be jointly and severally liable for all obligations of Tenant.

       SECTION 16.4 BROKER. Landlord and Tenant represent to each other that
they have not dealt with any brokers in connection with this Lease. Landlord and
Tenant acknowledge that the Nichols Company has served as consultant and will be
paid pursuant to a separate agreement. Landlord and Tenant shall indemnify and
hold each other harmless against any claims for brokerage or other commissions
arising by reason of a breach of the aforesaid representation and warranty.

       Section 16.5 Notices. All notices, demands and requests shall be in
writing, and shall be effectively served by forwarding such notice, demand or
request by certified or registered mail, postage prepaid, or by commercial
overnight courier service, or by hand delivery with signed receipts, addressed
as follows:

         (a)  IF ADDRESSED TO TENANT:

              Coherent Communications Systems Corp.
              (prior to the Commencement Date)
              44084 Riverside Parkway
              Leesburg, Virginia 22075
              Attn: Daniel L. McGinnis, CEO
              (after the Commencement Date: The Premises)

         with a copy to:

              McGuire, Woods, Battle & Boothe, L.L.P. 
              8280 Greensboro Drive, Suite 900 
              McLean, Virginia 22102 
              Attn: Stanley M. Franklin, Esq., and John G. Lavoie, Esq.

         (b)  IF ADDRESSED TO LANDLORD:

              Opus East, L.L.C.
              6707 Democracy Boulevard
              Suite 510
              Bethesda, Maryland 20817

                                       27
<PAGE>   28
         with a copy to:

              Opus U.S. Corporation 
              700 Opus Center 
              9900 Bren Road 
              Minnetonka, Minnesota 55343 
              Attn: Dan F. Nicol, Esq.

         and

              Hazel & Thomas, P.C. 
              3110 Fairview Park Drive 
              Suite 1400 
              Falls Church, Virginia 22042 
              Attn: Donna P. Shafer, Esq.

or at such other address as Landlord and Tenant may hereafter designate by
written notice to the other party. The effective date of all notices shall be
(i) three (3) days after the date of mailing if sent by United States Postal
Service, (ii) the date of delivery if sent by a nationally recognized overnight
courier service, or (iii) the date of receipt if sent by hand delivery with
signed receipts.

      SECTION 16.6 LANDLORD'S AGENT. All rights and remedies of Landlord under
this Lease or that may be provided by law may be executed by Landlord in its own
name individually, or in the name of its agent, and all legal proceedings for
the enforcement of any such rights or remedies, including those set forth in
Article 14, may be commenced and prosecuted to final judgment and execution by
Landlord in its own name or in the name of its agent.

      SECTION 16.7 QUIET POSSESSION. Landlord covenants and agrees that Tenant,
upon paying the Base Rent, Additional Rent and other charges herein provided for
and observing and keeping the covenants, agreements and conditions of this Lease
on its part to be kept and performed, shall lawfully and quietly hold, occupy
and enjoy the Premises during the term of this Lease without hindrance or
molestation by Landlord or by any person claiming under or through Landlord.

      SECTION 16.8 SUCCESSORS AND ASSIGNS. The covenants and agreements herein
contained shall bind and inure to the benefit of the Landlord, its successors
and assigns, and Tenant and its permitted successors and assigns.

      SECTION 16.9 SEVERABILITY. If any term or provision of this Lease shall to
any extent be held invalid or unenforceable, the remaining terms and provisions
of this Lease shall not be affected thereby, but each term and provision of this
Lease shall be valid and enforced to the fullest extent permitted by law. This
Lease shall be construed and enforced in accordance with the laws of the state 
in which the Premises are located.

      SECTION 16.10 NO ABANDONMENT OR WASTE. Tenant covenants not to do or
suffer any waste or damage or disfigurement or injury to the Premises or Office
Complex.

      SECTION 16.11 TRANSFERS BY LANDLORD. The term "Landlord" as used in this
Lease so far as covenants or obligations on the part of Landlord are concerned
shall be limited to mean and include only the owner or owners of the Office
Complex at the time in question, and in the event of any transfer or transfers
or conveyances the then grantor shall be automatically freed and released
(except to the extent otherwise provided in Section 16.20 hereof) from all
liability accruing from and after the date of such transfer or conveyance as
respects the performance of any covenant or obligation on the part of Landlord
contained in this Lease to be performed so long as the successor landlord agrees
to assume the original landlord's obligations and a copy of such instrument is
promptly delivered to Tenant. It is intended hereby that the covenants and
obligations contained in this Lease on the part of Landlord shall be binding on
the Landlord, its successors and assigns, only during and in respect to their
respective successive periods of ownership.

                                       28
<PAGE>   29
      In the event of a sale or conveyance by Landlord of the Office Complex or
any part of the Office Complex, the same shall operate to release Landlord from
any future liability upon any of the covenants or conditions herein contained
and in such event Tenant agrees to look solely to the responsibility of the
successor in interest of Landlord in and to this Lease. This Lease shall not be
affected by any such sale or conveyance, and Tenant agrees to attorn to the
purchaser or grantee, which shall be personally obligated on this Lease only so
long as it is the owner of Landlord's interest in and to this Lease.
Notwithstanding anything to the contrary contained in this Section 16.11,
Landlord shall not assign its interest in this Lease prior to the Commencement
Date without the prior written consent of Tenant.

      SECTION 16.12 HEADINGS. The marginal or topical headings of the several
articles and sections are for convenience only and do not define, limit or
construe the contents of said articles and sections.

      SECTION 16.13 WRITTEN AGREEMENT. All preliminary negotiations are merged
into and incorporated in this Lease, except for written collateral agreements
executed contemporaneouslv herewith.

      SECTION 16.14 MODIFICATIONS OR AMENDMENTS. This Lease can only be modified
or amended by an agreement in writing signed by the parties hereto. No receipt
of money by Landlord from Tenant or any other person after termination of this
Lease or after the service of any notice or after the commencement of any suit,
or after final judgment for possession of the Premises shall reinstate, continue
or extend the term of this Lease or affect any such notice, demand or suit, or
imply consent for any action for which Landlord's consent is required, unless
specifically agreed to in writing by Landlord. Any amounts received by Landlord
may be allocated to any specific amounts due from Tenant to Landlord as Landlord
determines.

      SECTION 16.15 LANDLORD CONTROL. Landlord shall have the right to
temporarily close any portion of the building area or land area to the extent as
may, in Landlord's reasonable opinion, be necessary to prevent a dedication
thereof or the accrual of any rights to any person or the public therein.

      SECTION 16.16 UTILITY EASEMENT. Provided such does not materially
interfere with Tenant's business or reduce the size or utility of the Premises
as contemplated by this Lease, Tenant shall permit Landlord (or its designees)
to erect, use, maintain, replace and repair pipes, cables, conduits, plumbing,
vents, and telephone, electric and other wires or other items, in, to and
through the Premises, as and to the extent that Landlord may now or hereafter
deem necessary or appropriate for the proper operation and maintenance of the
Office Complex.

      SECTION 16.17 NOT BINDING UNTIL PROPERLY EXECUTED. Employees or agents of
Landlord have no authority to make or agree to make a lease or other agreement
or undertaking in connection herewith. The submission of this document for
examination does not constitute an offer to lease, or a reservation of, or
option for, the Premises. This document becomes effective and binding only upon
the execution and delivery hereof by the proper officers of Landlord and by
Tenant. Tenant confirms that Landlord and its agents have made no
representations or promises with respect to the Premises or the making of or
entry into this Lease except as in this Lease expressly set forth, and agrees
that no claim or liability shall be asserted by Tenant against Landlord for, and
Landlord shall not be liable by reason of, breach of any representations or
promises not expressly stated in this Lease. This Lease, except for the Building
Rules and Regulations, in respect to which Section 16.18 of this Article shall
prevail, can be modified or altered only by agreement in writing between
Landlord and Tenant, and no act or omission of any employee or agent of Landlord
shall alter, change or modify any of the provisions hereof.

      SECTION 16.18 BUILDING RULES AND REGULATIONS. Tenant shall perform,
observe and comply with the Building Rules and Regulations of the Office Complex
as set forth below, with respect to the safety, care and cleanliness of the
Premises and the Office Complex, and the preservation of good order thereon,
and, upon written notice thereof to Tenant, Tenant shall perform, observe, and
comply with any changes, amendments or additions thereto as from time to time
shall be established and deemed advisable by Landlord for tenants of the Office
Complex. Notwithstanding the foregoing, in no event shall any amendments or
revisions to the Rules and Regulations change or alter Tenant's obligations or
rights under this Lease, and in the event of a discrepancy between the Rules and
Regulations and the Lease, the Lease shall govern.

                                       29
<PAGE>   30
      SECTION 16.19 COMPLIANCE WITH LAWS AND RECORDED COVENANTS. Tenant shall
not use the Premises or permit anything to be done in or about the Premises
which will, in any way, conflict with any law, statute, ordinance or
governmental rule or regulation now in force or which may hereafter be enacted
or promulgated. Tenant shall, at its sole cost and expense, promptly comply with
all laws, statutes, ordinances and governmental rules and regulations now in
force or which may hereafter be in force, and with the requirements of any fire
insurance underwriters or other similar body now or hereafter constituted
relating to or affecting the condition, use or occupancy of the Premises. Tenant
shall use the Premises and comply with any recorded covenants, conditions, and
restrictions affecting the Premises and the Office Complex as of the
commencement of the Lease or which are recorded during the lease term following
notice to and acceptance by Tenant.

      Tenant shall have the responsibility to comply with the requirements of
the ADA in the Premises only after the Commencement Date. As used in this Lease,
"ADA" shall mean the Americans with Disabilities Act of 1991, 42 U.S.C. Section
12.101 et seq. and all regulations applicable thereto promulgated as of the date
hereof (collectively, "ADA").

      SECTION 16.20 OBLIGATIONS SURVIVE TERMINATION. All obligations of Landlord
and Tenant hereunder not fully performed as of the expiration or earlier
termination of the term of this Lease shall survive the expiration or earlier
termination of the term hereof, including, without limitation, all payment or
repayment/refund obligations with respect to Operating Expenses and Real Estate
Taxes and all obligations concerning the condition of the Premises.

      SECTION 16.21 TENANT'S WAIVER. Intentionally Deleted.

      SECTION 16.22 AUTHORIZATION. Landlord and Tenant shall furnish to each
other, within ten (10) business days of written request from the other party, a
corporate resolution, proof of due authorization of partners, or other
appropriate and reasonable documentation evidencing the due authorization to
enter into this Lease.

      SECTION 16.23 NO PARTNERSHIP OR JOINT VENTURE. This Lease shall not be
deemed or construed to create or establish any relationship or partnership or
joint venture or similar relationship or arrangement between Landlord and Tenant
hereunder.

      SECTION 16.24 LANDLORD'S RIGHT TO SUBSTITUTE PREMISES. Intentionally
Deleted.

      SECTION 16.25 TENANT'S OBLIGATION TO PAY MISCELLANEOUS TAXES. Tenant shall
pay, prior to delinquency, all taxes assessed or levied upon its occupancy of
the Premises, or upon the trade fixtures, furnishings, equipment and all other
personal property Of Tenant located in the Premises, and when possible, Tenant
shall cause such trade fixtures, furnishings, equipment and other personal
property to be assessed and billed separately from the property of Landlord. In
the event any or all of Tenant's trade futures, furnishings, equipment or other
personal property, or Tenant's occupancy of the Premises, shall be assessed and
taxed with the property of Landlord, Tenant shall pay to Landlord its share of
such taxes within thirty (30) days after delivery to Tenant by Landlord of a
statement in writing setting forth the amount of such taxes applicable to
Tenant's personal property.

      SECTION 16.26 SIGNS. In addition to the signs shown on the Final Plans and
Specifications, Tenant may erect additional signs on the exterior or interior of
the Building or on the landscaped area adjacent thereto, provided that such sign
or signs are acceptable to Landlord in Landlord's reasonable discretion, and
such signs (a) do not cause any structural damage or other damage to the
Building; (b) do not violate applicable governmental laws, ordinances, rules or
regulations; (c) do not violate any existing restrictions affecting the Demised
Premises; and (d) are compatible with the architecture of the Building and the
landscaped area adjacent thereto. Landlord further agrees that Tenant's name and
the names of its key employees shall be listed on the lobby directory of the
Premises without additional cost to Tenant.

      SECTION 16.27 EXHIBITS. The following are made a part hereof, with the
same force and effect as if specifically set forth herein:

                                       30
<PAGE>   31
    (a)  Exhibit A - Legal Description of the Land
    (b)  Exhibit B - Work Agreement
    (c)  Exhibit C - Non Disturbance Agreement
    (d)  Exhibit D - Expansion Option
    (e)  Exhibit E - Rules and Regulations
    (f)  Exhibit F - Base Building
    (g)  Exhibit G - Budget for Operating Expenses

      SECTION 16.28 LANDLORD'S LIMITED LIABILITY. Anything contained in this
Lease to the contrary notwithstanding, but subject to the terms of this Section
16.28, from and after the Final Completion of the Building (as defined in the
Work Agreement), Tenant agrees that Tenant shall look solely to the estate and
property of Landlord in the Premises or the proceeds from the sale, transfer,
foreclosure, refinance or conversion thereof, and insurance and condemnation
proceeds for the collection of any judgment or other judicial process requiring
the payment of money by Landlord for any default or breach by Landlord under
this Lease, subject, however, to the prior rights of any mortgagee or Landlord
of the Premises. No other assets of Landlord or any partners, shareholders, or
other principals of Landlord shall be subject to levy, execution or other
judicial process for the satisfaction of Tenant's claim. In the event Tenant
obtains a final, non-appealable judgment against Landlord, but the estate and
property of Landlord in the Premises are not sufficient to satisfy the judgment,
then Tenant may, at its option, offset the judgment against Rent coming due
under the Lease and, if the judgment remains unsatisfied as of the end of the
term, extend the term and continue to offset its Rent obligations.

      SECTION 16.29 ROOFTOP RIGHTS. Subject to Landlord's review and prior
written approval, which shall not be unreasonably withheld, and subject to
compliance with applicable laws and all restrictions of record, Tenant shall at
all times during, the term of this Lease, have the right to use the Building's
shafts for conduits between the Premises and the roof of the Building for the
installation and maintenance of conduits and cables to extend to communications
equipment located or to be located on the roof. Further, subject to availability
of space and Landlord's prior written approval (not to be unreasonably withheld,
conditioned or delayed) of the size, location, esthetics, and height thereof,
Tenant shall have the right at all times to install and operate microwave or
satellite dishes or other antenna communications system on the roof of the
Building subject to compliance with all applicable laws and all restrictions or
record. Landlord's approval rights shall include without limitation, review and
approval of the procedures and personnel with respect to installation,
maintenance, and operation. Tenant shall not be obligated to pay rental for any
equipment which may be installed. Use of such roof space shall be subject to
reasonable rules and regulations specified by Landlord and to Tenant's obtaining
such insurance coverage as Landlord shall reasonably require. At the expiration
or earlier termination of the Lease, Tenant, at its expense, shall remove the
communications equipment. Any work required to restore the roof or any other
part of the Building from any damage occasioned by the installation,
maintenance, relocation or removal of the communications equipment shall be
borne by Tenant. Tenant shall indemnify and hold harmless Landlord from all
costs, damages, expenses, liabilities, and suits, including reasonable
attorneys' fees, occasioned by Tenant's installation, maintenance, relocation,
removal or use of the communications equipment, including without limitation,
any damage to property and/or injury or death to persons caused thereby from the
installation, maintenance, and operation. The installation, maintenance,
relocation, and removal of the communications equipment will be performed in
such a manner as not to interfere with the operation of the Building. All
communications equipment shall be maintained by the Tenant at Tenant's sole cost
and expense in good and safe condition. The communications equipment shall be
used solely by Tenant in the ordinary course of its business, and Tenant shall
not allow any parties other than Tenant to use such equipment or the rooftop
without Landlord's prior written consent, not be unreasonably withheld.

      SECTION 16.30 PARKING. Notwithstanding anything to the contrary contained
in this Lease, if any event or action or omission by Landlord renders the
parking areas for the Building and/or Tenant's parking space allocation
(including reserved spaces, if any) for whatever reason inaccessible or
unusable, or which causes the number of parking spaces for the Premises to be
reduced below applicable Loudoun County code requirements (which reasons may
include but are not limited to repairs, maintenance, casualty, condemnation, or
displacement or dislocation caused by future construction), Landlord shall
immediately provide substitute parking areas for Tenant's use and its invitees
which areas shall (i) cause no net reduction in Tenant's parking space
allocation, (ii) be similarly convenient in terms of location, quality and
safety, and (iii) except in the case of an emergency, be designated by prior
written notice to

                                       31
<PAGE>   32
Tenant with the exact location of such substitute parking areas subject to
Tenant's approval not to be unreasonably withheld, conditioned or delayed. In no
event shall Landlord charge any separate or additional charge or rent for use of
the parking areas located on the Property from time to time.

      SECTION 16.31 MEASUREMENT OF PREMISES. As used in this Lease, the term
"net rentable area" shall mean the number of square feet as measured in
accordance with the Greater Washington Commercial Association of Realtors
Standard Method of Measurement.

      SECTION 16.32 RENEWAL OPTIONS. Tenant shall have the right to renew and
extend the term of this Lease for the Renewal Terms (herein so called) upon and
subject to the following terms and conditions:

      Tenant may extend this Lease for two (2) Renewal Terms of five (5) years
each by Tenant's giving Landlord a Renewal Notice no more than six (6) months
prior to the expiration of the initial term or the immediately preceding Renewal
Term, as applicable. Such Renewal Term(s) shall commence immediately upon the
expiration of the initial term or subsequent Renewal Term, and upon exercise of
each renewal option the expiration date of the term shall automatically become
the last day of the applicable Renewal Term(s). If Tenant does not renew the
Lease in a timely manner for the Renewal Term(s), then Tenant's rights with
respect to all successive Renewal Term(s) shall expire and be of no further
force and effect.

      The exercise by Tenant of the renewal option(s) set forth herein must be
made, if at all, by delivery of the Renewal Notice to Landlord on or before the
dates set forth above. Once Tenant shall exercise such renewal option(s), Tenant
may not thereafter revoke such exercise. At Landlord's election, Tenant's
renewal options shall terminate and be of no further force or effect if (i) an
Event of Default exists under the Lease at the time Tenant attempts to exercise
its renewal option, (ii) Tenant defaults under any provision of the Lease after
exercising its renewal option and such default continues beyond any applicable
cure period provided in the Lease, (iii) at any time during the Term of the
Lease, as extended, Tenant assigns the Lease to a third party, or (iv) at the
time Tenant attempts to exercise its renewal option, Tenant has subleased or has
demonstrated an intention to sublease more than seventy percent (70%) or more
of the Premises to an unrelated third party.

      Tenant shall take the Premises "as is" for the Renewal Term(s) and, other
than as may then be a component of the "Fair Market Rental Rate", Landlord shall
have no obligation to make any improvements or alterations to same; provided,
however, Landlord shall comply with its repair and maintenance obligations as
set forth in this Lease.

      Annual Base Rent for the Renewal Term(s) shall be the "Fair Market Rental
Rate" multiplied by the number of square feet of net rentable area in the
Building. Within thirty (30) days after the date of Tenant's Renewal Notice,
Landlord and Tenant shall endeavor in good faith to agree upon the Fair Market
Rental Rate applicable to the Building for each year of the Renewal Term. In the
event Landlord and Tenant are unable to agree upon the Fair Market Rental Rate
within the aforesaid thirty (30) day period, Landlord and Tenant shall each
select a broker to determine the Fair Market Rental Rate within thirty five (35)
days after the date of the Renewal Notice. Each broker shall make an independent
determination of the Fair Market Rental Rate of the Building for each year of
the Renewal Term. If the two brokers so appointed agree on the Fair Market
Rental Rate for each year of the Renewal Term within forty (40) days after the
date of the Renewal Notice, the Fair Market Rental Rate shall be the amount
determined by them.

      If the two brokers so appointed do not agree on the Fair Market Rental
Rate within forty (40) days after the date of the Renewal Notice, the two
brokers shall jointly appoint a third broker on or before the forty fifth (45th)
day after the date of the Renewal Notice. The third broker shall make a
valuation within fifty (50) days after the date of the Renewal Notice and the
Fair Market Rental Rate for each year of the Renewal Term shall be an amount
equal to the quotient obtained by dividing the sum of the Fair Market Rental
Rates determined by the two brokers who were closest to each other in amount, by
two.

      Each broker appointed shall be an individual of recognized competence who
has a minimum of ten (l0) consecutive years' experience in the leasing of office
space in the suburban Northern Virginia area immediately preceding such
engagement. All valuations of the Fair Market Rental Rate shall be in writing,
shall be expressed in terms of an annual rent per square foot of rentable area,
and shall take into

                                       32
<PAGE>   33
consideration that the Premises are to be taken in "as is" condition for any
renewal period. Each broker shall determine the Fair Market Rental Rate on the
basis of all relevant factors affecting Fair Market Rental Rates such as
concessions then being offered in the marketplace. The party appointing each
broker shall be obligated, promptly after receipt ofthe valuation report
prepared by the broker appointed by such party, to deliver a copy of such
valuation report to the other party in the manner provided elsewhere in this
Lease for the giving of notices. If a third broker is appointed, the third
broker shall be directed, at the time of his appointment, to deliver copies of
his valuation report, promptly after its completion, to Landlord and Tenant in
the manner provided elsewhere in this Lease for the giving of notices. The
expenses of each of the first two brokers appointed shall be borne by the party
appointing such broker. The expenses of the third broker appointed shall be paid
one-half by Landlord and one-half by Tenant.

      Tenant shall not be entitled to any rental abatement concessions,
additional renewal options or other similar concessions during any Renewal Term,
except to the extent they constitute part of the determination of the Fair
Market Rental Rate.

      Except as set forth herein, the leasing of the Premises for the Renewal
Term(s) shall be upon the same terms and conditions as are applicable for the
initial term and any subsequent Renewal Term(s), and shall be upon and subject
to all of the provisions of this Lease, including, without limitation, the
obligation of Tenant to pay any costs or amounts payable by Tenant to Landlord
under the Lease.

      Tenant's rights under this Section 16.32 shall be personal to Tenant and
shall not inure to the benefit of any assignee or occupant of the Premises other
than an assignee which is a successor corporation into which or with which
Tenant is merged or consolidated or which acquires substantially all of Tenant's
assets and property, or to any subsidiary, affiliate or parent company of
Tenant, or any subsidiary of the parent company of Tenant.

      SECTION 16.33 EXPANSION OPTION. Landlord has negotiated an option to
purchase the parcel immediately adjacent to the Land containing approximately
5.24 acres upon the terms and conditions more particularly set forth in the
Standard Retail Purchase and Sale Agreement ("Purchase Contract") attached
hereto as Exhibit D. As additional consideration for this Lease, Landlord hereby
assigns any and all interest in and to such option to Tenant and shall request
the Memorandum of Option contemplated by section 9.18.c. be prepared with Tenant
as the holder of the option. Tenant shall have the right, at its expense, to
record the memorandum among the land records of Loudoun County, Virginia.

      SECTION 16.34 RIGHT OF FIRST OFFER TO PURCHASE. Landlord shall notify
Tenant of its intent to market the Property for sale, and shall accord Tenant
thirty (30) days from the date of notice (which notice shall include the
purchase price to be sought by Landlord) to reach agreement with Landlord on
terms and conditions of sale, in which event, the parties will enter into a
contract memorializing such terms and proceed to closing. If the parties do not
reach agreement within such thirty (30) day period, Landlord shall have the
absolute right to sell the Property to any other party on such terms and
conditions as may be acceptable to Landlord in its sole discretion.

      SECTION 16.35 INDOOR AIR QUALITY. Landlord shall have the Building tested
for indoor air quality on an annual basis. Landlord shall promptly provide to
Tenant copies of such annual written test reports relating to the air quality in
the Building, or any other written report, information, or data prepared as an
evaluation ofthe indoor air quality of the Building. Landlord shall implement
recommendations set forth in the report as appropriate to cause all air quality
in the Building to conform to then existing local, state or federal regulations.

      In the event that any problem with indoor air quality which is caused by
the negligent actions or omissions of Landlord or Landlord's licensees,
employees, agents, contractors or invitees use or occupancy of the Building
prevents Tenant from conducting its business in the Building for five (5)
consecutive business days, then beginning on the sixth (6th) consecutive
business day, Tenant's obligation to pay Rent shall abate until the air quality
condition is corrected and Tenant is able to resume its business operations in
the Building.

      Tenant covenants and agrees that the Building shall be a "smoke free"
building.

                                       33
<PAGE>   34
      SECTION 16.36 LANDLORD'S REPRESENTATIONS AND WARRANTIES. Landlord
represents and warrants to Tenant as follows:

      (i) To the best of Landlord's knowledge and belief and based on an
environmental report prepared by ECS Limited dated July 26, 1996, a copy of
which has been delivered to Tenant, there are no Hazardous Materials on, in or
under the Property, Building or Office Complex. Landlord further represents that
the current owner of the Property ("Owner") has not provided Landlord with, nor
has Landlord otherwise received, copies of any summons, citation, directive,
notice, complaint, letter or other written communication, from the United States
Environmental Protection Agency or other governmental authority concerning any
alleged violation of any environmental law or rule or regulation at the
Property. Landlord further represents and warrants that, to its actual
knowledge, there are no buried fuel tanks within the Property or the Option
Parcel (as defined in the Purchase Contract) or within any land adjoining or in
the immediate vicinity of either.

      The representations and warranties contained in this Section 16.36 shall
be true and correct as of the Commencement Date, and Landlord shall indemnify
Tenant and hold it harmless against any claims, damages, losses or liabilities
(including reasonable attorney's fees) incurred by Tenant and arising from any
breach of same.

      (ii) To the best of Landlord's knowledge and belief, the Premises will be
in compliance with applicable laws, statutes, ordinances and regulations in
effect as of the Commencement Date. Landlord hereby agrees that Tenant shall
have no responsibility for failure of the Premises or the Office Complex to
comply with applicable laws, statutes, ordinances and regulations which are in
effect and applicable to the Premises or the Office Complex as of the
Commencement Date.

      (iii) As of the Commencement Date, the Premises shall be in compliance
with all recorded covenants, conditions and restrictions affecting the Premises.

      (iv) To the best of Landlord's knowledge and belief, the Premises will be
in compliance with the requirements of the ADA as of the Commencement Date.
Landlord further represents and warrants that the work to be performed in
accordance with the Work Agreement shall be in compliance with or shall be made
to comply with the requirements of the ADA.

      (v) To the best of Landlord's knowledge, fiber optic service is available
to the development of which the Property is a part. Landlord will cooperate with
Tenant at Tenant's sole cost and expense to bring the fiber optic service to the
Premises.

      (vi) Based on a representation and warranty from Owner contained in the
Purchase Contract, Owner has not received any written notice of any violation
("Violation Notice") of any applicable laws, ordinances, regulations, statutes,
rules and restrictions pertaining to and affecting the Property. Landlord
further represents and warrants that it has not received any Violation Notice
relating to the Property.

      (vii) Based on a representation and warranty from Owner contained in the
Purchase Contract, there is no pending, or to Owner's actual knowledge,
threatened condemnation or similar proceeding affecting the Property or any
portion thereof, and Owner has no knowledge that any such action is presently
contemplated. Landlord represents and warrants that to its actual knowledge,
there is no such condemnation proceeding affecting any portion of the Property,
and Landlord does not have knowledge that a condemnation proceeding affecting
the Property is contemplated.

      (viii) Based on a representation and warranty from Owner contained in the
Purchase Contract, (a) Owner has granted to no other person, firm corporation or
other entity any right or option to acquire the Property or any portion thereof
or any interest therein from Owner, and (b) Owner shall not enter into any other
agreement, contract or option to sell the Property or any portion thereof or
interest therein with any other person, firm or entity during the term of the
Purchase Contract. Landlord represents and warrants that, to its knowledge,
neither Landlord nor Owner has granted any other person, firm, corporation or
entity any right or option to acquire any portion of the Property or the Option
Parcel.

      (ix) Based on a representation and warranty from Owner contained in the
Purchase Contract, Owner has not received any notice regarding proceedings to
change the zoning or land use classification

                                       34
<PAGE>   35
of the Property or the conditions applicable thereto. Landlord represents and
warrants that it has not received any such notice to change the zoning
applicable to the Property.

      (x) Based on a representation and warranty from Owner contained in the
Purchase Contract, Owner has not received any notice that the Property was ever
used as a landfill or as a garbage dump during the period of Owner's ownership.
Landlord represents and warrants that it has not received any notice that the
Property was ever used as a landfill or a garbage dump during the period of
Owner's ownership.

      (xi) Based on a representation and warranty from Owner contained in the
Purchase Contract, neither Owner nor any of its agents or employees have made
unrecorded commitments or side agreements with any governmental authority,
utility company, school board, church or other religious body, or any homeowners
or homeowners' association, or with any other organization, group, party, or
individual (collectively, "Side Agreements"), relating to the Property which
would impose an obligation upon Landlord or its successors or assigns to make
any contribution or dedication of money or land or to construct, install, or
maintain any improvements of a public or private nature on or off the Property.
Landlord represents and warrants that, to its knowledge, Owner has not entered
into any such Side Agreements.

      (xii) Based on a representation and warranty from Owner contained in the
Purchase Contract, Owner has not received written notice ("Preservation Notice")
that the Property has not been identified by any governmental body or private
organization as the habitat of any species of plant or animal which is
endangered or which requires special conservation measures. Landlord represents
and warrants that Landlord has not received any such Preservation Notice.

      (xiii) Based on a representation and warranty from Owner contained in the
Purchase Contract, Owner has not received written knowledge that any human
burial grounds or archaeological sites have been identified as existing upon the
Property and no improvements upon the Property have been designated by any
governmental authority as having special architectural or historical
significance. Landlord represents and warrants that, to its knowledge, the
Property has not been so designated as having special architectural or
historical significance.

      (xiv) After Closing (as defined in the Purchase Contract), Landlord will
own fee simple title to the Property, free and clear of all restrictions, liens,
encumbrances, easements, exceptions, covenants, conditions and reservations,
except for Permitted Exceptions (as defined in the Purchase Contract), financing
agreements for which Tenant has received a non-disturbance agreement as
contemplated by Section 15.1 of this Lease, and other title matters expressly
permitted by the terms of this Lease.

      IN WITNESS WHEREOF the parties have executed this Lease as of the day and
year first above written.

                               Landlord:                        
                               
                               Opus East, L.L.C.
                               
                               By    [SEAL]
                               
                               Its President
                               
                               Tenant:
                               
                               Coherent Communications
                               System Corp.
                               By    [SEAL]
                               Its CEO

                                       35