Document:

<PAGE>

                               LEASE AGREEMENT BETWEEN

                        CARRAMERICA REALTY L.P., AS LANDLORD,

                                         AND

                             OBJECTSPACE, INC., AS TENANT

                                    APRIL 29, 1997

<PAGE>

                                  TABLE OF CONTENTS

<TABLE>
<CAPTION>
                                                                           PAGE
                                                                           ----
<S>    <C>                                                                 <C>
1.     DEFINITIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
2.     PREMISES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
3.     TERM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
4.     USE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
5.     RENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
       5.1    Base Rent . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
       5.2    Additional Rent . . . . . . . . . . . . . . . . . . . . . . . . 2
       5.3    Parking Charge. . . . . . . . . . . . . . . . . . . . . . . . . 2
       5.4    Payment of Rent . . . . . . . . . . . . . . . . . . . . . . . . 3
       5.5    Delinquent Payments.. . . . . . . . . . . . . . . . . . . . . . 3
       5.6    Prepaid Rent. . . . . . . . . . . . . . . . . . . . . . . . . . 3
6.     CONSTRUCTION OF IMPROVEMENTS.. . . . . . . . . . . . . . . . . . . . . 3
       6.1    General; ADA Compliance . . . . . . . . . . . . . . . . . . . . 3
       6.2    Access by Tenant Prior to Commencement of Term. . . . . . . . . 4
       6.3    Commencement Date; Adjustments to Commencement Date . . . . . . 4
       7.     SERVICES TO BE FURNISHED BY LANDLORD. . . . . . . . . . . . . . 5
       7.1    General . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
       7.2    Keys. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
       7.3    Tenant Identity . . . . . . . . . . . . . . . . . . . . . . . . 7
       7.4    Charges . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
       7.5    Operating Hours . . . . . . . . . . . . . . . . . . . . . . . . 7
8.     REPAIR AND MAINTENANCE.. . . . . . . . . . . . . . . . . . . . . . . . 8
       8.1    By Landlord . . . . . . . . . . . . . . . . . . . . . . . . . . 8
       8.2    By Tenant . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
9.     TAXES ON TENANT'S PROPERTY . . . . . . . . . . . . . . . . . . . . . . 8
10.    TRANSFER BY TENANT . . . . . . . . . . . . . . . . . . . . . . . . . . 8
       10.1   General.. . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
       10.2   Conditions. . . . . . . . . . . . . . . . . . . . . . . . . . . 9
       10.3   Liens . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
11.    ALTERATIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
12.    SPECIFICALLY PROHIBITED USES.. . . . . . . . . . . . . . . . . . . . .11
13.    ACCESS BY LANDLORD . . . . . . . . . . . . . . . . . . . . . . . . . .11
14.    CONDEMNATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
15.    CASUALTY.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
       15.1   General . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
       15.2   Acts of Tenant. . . . . . . . . . . . . . . . . . . . . . . . .12
16.    SUBORDINATION AND ATTORNMENT.. . . . . . . . . . . . . . . . . . . . .13
       16.1   General . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
       16.2   Attornment. . . . . . . . . . . . . . . . . . . . . . . . . . .13
17.    INSURANCE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
       17.1   General . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
       17.2   WAIVER OF SUBROGATION.. . . . . . . . . . . . . . . . . . . . .14
       17.3   Landlord's Insurance. . . . . . . . . . . . . . . . . . . . . .14
18.    INDEMNITY. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
19.    THIRD PARTIES; ACTS OF FORCE MAJEURE.. . . . . . . . . . . . . . . . .15
20.    SECURITY INTEREST. . . . . . . . . . . . . . . . . . . . . . . . . . .15
21.    CONTROL OF COMMON AREAS. . . . . . . . . . . . . . . . . . . . . . . .15
22.    INTENTIONALLY DELETED. . . . . . . . . . . . . . . . . . . . . . . . .15
23.    QUIET ENJOYMENT. . . . . . . . . . . . . . . . . . . . . . . . . . . .16
24.    DEFAULT BY TENANT. . . . . . . . . . . . . . . . . . . . . . . . . . .16

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       24.1   Events of Default . . . . . . . . . . . . . . . . . . . . . . .16
       24.2   Remedies of Landlord. . . . . . . . . . . . . . . . . . . . . .16
       24.3   Payment by Tenant.. . . . . . . . . . . . . . . . . . . . . . .17
       24.4   Reletting . . . . . . . . . . . . . . . . . . . . . . . . . . .17
       24.5   Landlord's Right to Pay or Perform. . . . . . . . . . . . . . .17
       24.6   No Waiver . . . . . . . . . . . . . . . . . . . . . . . . . . .18
25.    DEFAULTS BY LANDLORD . . . . . . . . . . . . . . . . . . . . . . . . .18
26.    RIGHT OF REENTRY . . . . . . . . . . . . . . . . . . . . . . . . . . .18
27.    MISCELLANEOUS. . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
       27.1   Independent Obligations . . . . . . . . . . . . . . . . . . . .19
       27.2   Time of Essence.. . . . . . . . . . . . . . . . . . . . . . . .19
       27.3   Applicable Law. . . . . . . . . . . . . . . . . . . . . . . . .19
       27.4   Assignment by Landlord. . . . . . . . . . . . . . . . . . . . .19
       27.5   Commencement Date and Estoppel Certificates . . . . . . . . . .19
       27.6   Signs, Building Name and Building Address.. . . . . . . . . . .19
       27.7   Notices.. . . . . . . . . . . . . . . . . . . . . . . . . . . .20
       27.8   Entire Agreement, Amendment and Binding Effect. . . . . . . . .20
       27.9   Severability. . . . . . . . . . . . . . . . . . . . . . . . . .20
       27.10  Number and Gender, Captions and References. . . . . . . . . . .21
       27.11  Attorneys' Fees . . . . . . . . . . . . . . . . . . . . . . . .21
       27.12  Brokers.. . . . . . . . . . . . . . . . . . . . . . . . . . . .21
       27.13  Interest on Tenant's Obligations. . . . . . . . . . . . . . . .21
       27.14  Authority . . . . . . . . . . . . . . . . . . . . . . . . . . .21
       27.15  Recording . . . . . . . . . . . . . . . . . . . . . . . . . . .21
       27.16  Exhibits. . . . . . . . . . . . . . . . . . . . . . . . . . . .21
       27.17  Multiple Counterparts . . . . . . . . . . . . . . . . . . . . .21
28.    SPECIAL PROVISIONS . . . . . . . . . . . . . . . . . . . . . . . . . .21
       28.1   Roof Rights.. . . . . . . . . . . . . . . . . . . . . . . . . .21
       28.2   Security Deposit: Letter of Credit. . . . . . . . . . . . . . .23
       28.3   Rules and Regulations.. . . . . . . . . . . . . . . . . . . . .24
       28.4   Consents. . . . . . . . . . . . . . . . . . . . . . . . . . . .24
</TABLE>

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<PAGE>

                                   LEASE AGREEMENT

       THIS LEASE AGREEMENT (this "LEASE") is entered as of April 29, 1997,
between CarrAmerica Realty, L.P., a Delaware limited partnership ("LANDLORD"),
and ObjectSpace, Inc., a Texas corporation ("Tenant").

1.     DEFINITIONS.  The definitions of certain of the capitalized terms used in
this Lease are set forth in the Glossary of Defined Terms attached hereto as
EXHIBIT A.

2.     PREMISES.  Subject to the provisions of this Lease, Landlord hereby
leases to Tenant, and Tenant hereby leases from Landlord, approximately 28,606
rentable square feet of space in the Building, which space is outlined on the
floor plan attached hereto as EXHIBIT B. In connection with such demise,
Landlord hereby grants to Tenant the non-exclusive right to use during the Term
all Common Areas designed for the use of all tenants in the Building, in common
with all tenants in the Building and their invitees, for the purposes for which
designed and in accordance with all Legal Requirements. By occupying the
Premises, Tenant accepts the Premises as being suitable for Tenant's intended
use of the Premises, but such acceptance shall not limit Landlord's obligations
specifically set forth hereinafter.

3.     TERM.  The Term of this Lease shall commence on the Commencement Date
(which is scheduled to be August 1, 1997) and shall expire at 5:00 p.m. March
31, 2003, unless earlier terminated as provided herein (the "Term"), subject to
Section 6.3.

4.     USE.  Tenant shall occupy and use the Premises solely for lawful, general
business office purposes in strict compliance with the Building Rules and
Regulations from time to time in effect and all other Legal Requirements.
Tenant's permitted use shall include non-retail kitchen and eating facilities,
computer and telecommunications facilities (which shall not include call
centers), data processing and transmission, including rooftop satellite
communications (to the extent permitted under Section 28.1), accounting
facilities, conference and meeting facilities, and copying facilities. Tenant's
intended uses will not cause insurance premiums for the Building to be
increased.

       Tenant acknowledges the purpose of its first floor occupancy is as a
training facility and there exists limited parking surrounding the Building for
Tenant's contemplated trainees. Tenant hereby agrees to use commercially
reasonable efforts to encourage its trainees to locate alternative
transportation methods and parking sources. Tenant further acknowledges and
agrees to cause its trainees and students to comply with the Building Rules and
Regulations.

5.     RENT.

       5.1    BASE RENT.  In consideration of Landlord's leasing the Premises to
Tenant, Tenant shall pay to Landlord as follows:

<TABLE>
<CAPTION>
                                               Monthly         Annual
              Time Period                      Base Rent       Base Rent
              -----------                      ---------       ---------
       <S>                                    <C>             <C>
       August 1, 1997 - September 30, 1999    $42,909.00      $514,908.00

       October 1, 1999 - March 31, 2003       $48,868.58      $586,422.96
</TABLE>

       In the event that the actual Commencement Date is a date other than
August 1, 1997, Landlord shall readjust the monthly Base Rent throughout the
Term of this Lease so that the effective monthly

                                                                      Page 1
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rental rate of this Lease for the initial Term is $19.50 per rentable square
foot of space in the Premises. The Base Rent set forth in this Section 5.1 is
a negotiated figure and shall govern whether or not the actual gross rentable
square footage of the Premises is the same as set forth in Section 2 hereof
or changes pursuant to the standards set in the definition of Net Rentable
Area. Tenant shall have no right to withhold, deduct or offset any amount of
the monthly Base Rent or any other sum due hereunder even if the actual gross
rentable square footage of the Premises is less than that set forth in
Section 2 hereof or changes pursuant to the standards set forth in the
definition of Net Rentable Area.

       5.2    ADDITIONAL RENT.  For purposes of this Lease, Tenant's "ADDITIONAL
RENT" for any Fiscal Year (or portion thereof) shall mean the product of (a) Net
Rentable Area of the Premises MULTIPLIED BY (b) the difference between (i) the
Operating Expenses DIVIDED BY the Net Rentable Area of the Building MINUS (ii)
the Expense Stop, all as applicable for the period in question. By the
Commencement Date, Landlord shall estimate the Additional Rent to be due by
Tenant for the balance of the Fiscal Year in which the Commencement Date occurs.
Thereafter, unless Landlord delivers to Tenant a revision of the estimated
Additional Rent, Tenant shall pay to Landlord, coincident with Tenant's payment
of Base Rent, an amount equal to the estimated Additional Rent for the remainder
of such year divided by the number of months remaining in such year. From time
to time during any Fiscal Year, Landlord may estimate and re-estimate the
Additional Rent to be due by Tenant for that Fiscal Year and deliver a copy of
the estimate or re-estimate to Tenant. Thereafter, the monthly installments of
Additional Rent payable by Tenant shall be appropriately adjusted in accordance
with the estimation so that, by the end of the Fiscal Year, Tenant shall have
paid all of the Additional Rent as estimated by Landlord. After the conclusion
of each Fiscal Year during the Term, and after the termination or expiration of
the Term, Landlord shall deliver to Tenant a statement of actual Additional Rent
due by Tenant for the Fiscal Year (or, with respect to termination or
expiration, the portion of the Fiscal Year) just ended.  Within thirty (30) days
thereafter, Tenant shall pay to Landlord or Landlord shall credit against the
next installment of Additional Rent due by Tenant (or Landlord shall refund to
Tenant, if the Term has expired and all payments due by Tenant to Landlord have
been paid in full) the difference between the actual Additional Rent due for
such year and the estimated Additional Rent paid by Tenant during such year. In
the event that Tenant is not satisfied with the statements of actual Additional
Rent submitted by Landlord, Tenant shall have the annual right, at Tenant's
expense and after giving twenty (20) days' prior written notice to Landlord, to
cause a nationally recognized firm of independent certified public accountants
reasonably acceptable to Landlord (similar to the "big six" firms as that term
is used on the date hereof) to make a special audit of all books and records
pertaining to the Operating Expenses and the statements of Additional Rent for
any periods within two (2) Fiscal Years prior to the review; provided, however,
no review shall extend to periods of time preceding the Fiscal Year within which
the Commencement Date falls. If any such audit reveals that Landlord overcharged
Tenant for Operating Expenses by more than five percent (5%) in any one year,
Landlord will pay the proportionate cost for such audit for the year(s) in which
Landlord was found to have overcharged Tenant in excess of five percent (5%). If
any such audit indicates that the statement submitted to Tenant is incorrect,
Landlord shall pay to Tenant any overpayment or Tenant shall pay to Landlord any
underpayment, as the case may be, which is established by any such audit. Any
payments required to be made by the parties pursuant to the preceding sentence
shall be due and payable within thirty (30) business days after receipt of such
audit by the party required to make such payment.

       5.3    PARKING CHARGE.  During the Term, Landlord will provide unassigned
surface parking to Tenant at no additional cost to Tenant in a ratio of one (1)
unassigned surface parking space for each 275 rentable square feet of space in
the Premises up to 20,000 rentable square feet, and one (1) unassigned covered
parking space for each 2,000 rentable square feet of space in the Premises up to
20,000 rentable square feet; thereafter, Landlord will provide unassigned
surface and covered parking to Tenant in a ratio of one (1) parking space for
each 333 rentable square feet of space in the Premises over 20,000 rentable
square feet, provided that unassigned covered parking shall not exceed a ratio
of one (1) parking space

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for each 2,000 rentable square feet of space in the Premises over 20,000
rentable square feet. For purposes of parking allocations, trainees and
students will be included in Tenant's overall usage calculations. All
parking, whether covered or uncovered, shall be used on a first-come,
first-served, basis. In the future, in the event Landlord institutes a parking
control system for the Complex, Tenant will use its best efforts to obtain a
completed registration form from Tenant's trainees, students and employees
with respect to vehicles driven onto the Complex by Tenant's trainees,
students and employees, returning same to Landlord, and cause such trainees,
students and employees to display Landlord's parking identification within
their vehicle(s). Contemporaneously with the payment of the first (1st)
installment of Rent, Landlord will issue to Tenant twenty-one (21) access
cards. Tenant shall pay to Landlord as Additional Rent an amount equal to
Twenty Dollars ($20.00) each for any additional and/or replacement access
card that Tenant needs to gain access to the Building.

       5.4    PAYMENT OF RENT.  Except as otherwise expressly provided in this
Lease, all Rent shall be due in advance monthly installments on the first day of
each calendar month during the Term. Rent shall be paid to Landlord at its
address recited in Section 27.7 or to such other person or at such other address
as Landlord may from time to time designate in writing. Rent shall be paid
without notice, demand, abatement, deduction or offset in legal tender of the
United States of America, except as expressly provided elsewhere in this Lease.
If the Term commences or ends on other than the first or the last day of a
calendar month, the Rent for the partial month shall be prorated on the basis of
the number of days during the month for which the Term was in effect. If the
Term commences or ends on other than the first or the last day of a Fiscal Year,
the Additional Rent for the partial Fiscal Year shall be prorated on the basis
of the number of days during the Fiscal Year for which the Term was in effect.

       5.5    DELINQUENT PAYMENTS.  All Rent and other payments required of
Tenant hereunder (minus the late charge) shall bear interest from the date due
until the date paid at the rate of interest specified in Section 27.13.
Alternatively, Landlord may charge Tenant, as additional Rent hereunder, a fee
equal to five percent (5%) of the delinquent payment to reimburse Landlord for
its cost and inconvenience incurred as a consequence of Tenant's delinquency
commencing on the fourth (4th) day after the due date for such payment. In no
event, however, shall the charges permitted under this Section 5.5 or elsewhere
in this Lease, to the extent the same are considered to be interest under
applicable law, exceed the maximum rate of interest allowable under applicable
law.

       5.6    PREPAID RENT.  Simultaneously with execution hereof, Landlord
hereby acknowledges receipt of $42,909.00, representing the first monthly
installment of Base Rent paid in advance, to be applied to the Rent for the
first month of the Term when due.

6.     CONSTRUCTION OF IMPROVEMENTS.

       6.1    GENERAL; ADA COMPLIANCE.  Subject to events of Force Majeure,
Landlord shall install, furnish, perform and apply, at its expense, the
Landlord's Work as specified in the Work Letter. Performance of the Landlord's
Work shall constitute Landlord's sole construction obligation to Tenant under
this Lease. Tenant will assure that the plans and specifications for its
improvements, as well as its business operations within the Premises comply with
the Americans With Disabilities Act of 1990, as amended, and all related state
and local laws (collectively, the "ADA"). Landlord will be responsible for all
ADA compliance for the remainder of the Building (taking into account other
tenants' obligations to comply with the ADA and the fact that the Building was
constructed before the effective date of the ADA). Landlord shall be responsible
for ensuring the Common Areas of the Building comply with all accessibility
requirements and laws. Tenant shall have the fight to use any and all existing
improvements or equipment on the Premises. Tenant shall not be charged for any
existing improvements or equipment. Window blinds will remain as existing. Prior
to the Commencement Date, missing or damaged blinds will

                                                                      Page 3
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be replaced at cost paid from the Leasehold Improvements Allowance. Landlord
will repair any existing water leaks prior to the Commencement Date at its
expense and not as a deduction from the Leasehold Improvements Allowance.
Tenant shall be allowed to use existing communications conduits between the
floors of the Building and to install additional communications conduits
within floors on which the Premises are located, extending to the roof to the
extent permitted by Section 28.1. Tenant shall be allowed to use floor cores
so long as precautionary measures are taken during construction, and provided
the floor cores do not interfere with the structural integrity of the
Building. Within two (2) weeks after execution of this Lease, Landlord shall,
at its cost, and without reimbursement from Tenant or the Leasehold Improvements
Allowance, deliver to Tenant base building plans and specifications reflecting
existing conditions for Tenant's space planner/architect to prepare space
plans.  The contractors and subcontractors employed to perform Landlord's
Work shall not be deemed to be Tenant's contractors or subcontractors, shall
be awarded contracts based on a competitively bid system involving at least
three (3) different contractors, and shall be subject to Tenant's approval,
not to be unreasonably withheld. No construction management fee shall be
payable to Landlord hereunder. Teant shall have the right to select any
architect, space planner, and engineer it desires, subject to Landlord's
approval, which shall not be unreasonably withheld. Landlord shall pay,
without reimbursement from Tenant, the costs incurred by Landlord to review
and approve plans and specifications.

       6.2    ACCESS BY TENANT PRIOR TO COMMENCEMENT OF TERM. Provided that
Tenant obtains and delivers to Landlord the certificates or policies of
insurance called for in Section 17.1, Landlord, in its reasonable discretion,
may permit Tenant and its employees, agents, contractors and suppliers to enter
the Premises before the Commencement Date [and such entry, alone, shall not
constitute Tenant's taking possession of the Premises for the purpose of Section
6.3(c)) to prepare the Premises for Tenant's occupancy. Tenant and each other
person or firm, who or which enters the Premises before the Commencement Date
shall conduct itself so as to not unreasonably interfere with Landlord or other
occupants of the Building. Landlord may withdraw any permission granted under
this Section 6.2 upon twenty-four (24) hours' notice to Tenant if Landlord, in
its reasonable discretion, determines that any such interference has been or may
be caused. Any prior entry shall be under all of the terms of this Lease (other
than the obligation to pay Base Rent and Additional Rent) and at Tenant's sole
risk. Landlord shall not be liable in any way for personal injury, death or
property damage (including damage to any personal property which Tenant may
bring into, or any work which Tenant may perform in, the Premises) which may
occur in or about the Complex by Tenant or such other person or firm as a result
of any prior entry.

       6.3    COMMENCEMENT DATE; ADJUSTMENTS TO COMMENCEMENT DATE.  For purposes
of this Lease, the "COMMENCEMENT DATE" shall mean the earliest of: (a) five (5)
days after Landlord notifies Tenant that Landlord has substantially completed
the Landlord's Work and the Tenant Improvements have passed final inspection by
the city of Addison, Texas; (b) the date on which Landlord would have
substantially completed the Landlord's Work and tendered possession of the
Premises to Tenant but for (i) the delay or failure of Tenant to furnish
information or other matters required in the Work Letter, (ii) Tenant's request
for changes in the Plans or non-Building Standard Items or (iii) any other
action or inaction of Tenant, or any person or firm employed or retained by
Tenant (collectively, items (i), (ii) and (iii) shall hereinafter be referred to
as "Tenant Delay"); (c) the date on which Tenant takes possession of the
Premises; and (d) August 1, 1997; provided that Landlord has made the Premises
available to Tenant's architect as provided in the Work Letter on or before June
15, 1997, that the Premises are made available to Tenant's architect as provided
in the Work Letter.  If by the scheduled Commencement Date specified in Section
3 the Landlord's Work has not been substantially completed or Landlord is unable
to tender possession of the Premises to Tenant, through no Tenant Delay, and
such failure to substantially complete prevents Tenant from legally occupying
the Premises, thereby using the Premises for their intended purpose, all as
reasonably determined by Landlord, then the Commencement Date (and the
commencement of payment of Base Rent and Additional Rent) shall be postponed
until the Landlord's

                                                                      Page 4
<PAGE>

Work is substantially completed as reasonably determined by Landlord.  Except
as otherwise provided hereinbelow, the postponement of the payment of Base
Rent and Additional Rent under this Section 6.3 shall be Tenant's exclusive
remedy for Landlord's delay in completing the Landlord's Work or tendering
possession of the Premises to Tenant.  Notwithstanding the foregoing, in the
event Tenant has prepared and Landlord has approved the construction drawings
relating to Landlord's Work on or before June 15, 1997, and the actual
Commencement Date with respect to that portion of the Premises other than the
Ground Floor Premises has not occurred prior to December 15, 1997, and such
delay is not a result of Tenant Delay, special order materials or Force
Majeure, then Tenant shall have the option to terminate this Lease by giving
written notice to Landlord during the period commencing on December 16, 1997,
and ending on December 30, 1997.  In the event Tenant does not give such
written notice to Landlord within such period, this Lease shall continue in
full force and effect and Tenant shall not have the right to terminate this
Lease pursuant to this Section 6.3.  Failure by Tenant to deliver to Landlord
construction drawings relating to Landlord's Work by June 15, 1997, shall
void Tenant's termination option described above.  In the event Tenant has
prepared and Landlord has approved the construction drawings relating to
Landlord's Work on or before June 15, 1997, and the actual Commencement Date
with respect to the Ground Floor Premises has not occurred prior to December
15, 1997, and such delay is not a result of Tenant Delay, special order
materials or Force Majeure, then Tenant shall not have the option to
terminate this Lease but instead Landlord shall give Tenant a credit against
the Base Rent allocable to the Ground Floor Premises in an amount equal to
two (2) days of base Rent allocable to the Ground Floor Premises for every
one (1) day that the actual Commencement Date occurs after December 15, 1997,
which rent credit shall be applied against Base Rent due and payable by
Tenant in respect of the Ground Floor Premises after the Commencement Date
occurs in respect thereof.  In the event the Commencement Date does not occur
at the same time in connection with that portion of the Premises other than
the Ground Floor Premises and the Ground Floor Premises, then Base Rent and
Additional Rent due and payable by Tenant under this Lease shall be prorated
for such respective portions of the Premises based upon the rentable square
footage allocable to each of such portions of the Premises.  Within thirty
(30) days after the actual Commencement Date with respect to the Premises,
or, in the event the actual Commencement Date for the portion of the Premises
other than the Ground Floor Premises differs from the Commencement Date for
such Ground Floor Premises, within thirty (30) days after the respective
Commencement Dates therefor, Landlord and Tenant shall execute a Commencement
Date agreement setting forth the exact Commencement Date and the expiration
date of this Lease.

       7.     SERVICES TO BE FURNISHED BY LANDLORD.

       7.1    GENERAL.  Landlord shall provide to Tenant, the cost for each
shall be included as Operating Expenses and not as an additional or separate
charge to Tenant, the level and quality of services generally provided by
landlords of office buildings of similar size, age and construction in the
Quorum, Addison, Texas, submarket. Subject to applicable Legal Requirements, and
repair and maintenance requirements from time to time, Landlord shall furnish
the following services:

              (a)    Air-conditioning and heating to the Premises during
       Building Operating Hours, at such temperatures and in such amounts as are
       described on EXHIBIT H. Tenant acknowledges that heat sources, such as
       specialized data processing equipment and sophisticated telephone
       systems, cannot be supported with standard air-conditioning service to be
       provided to the Premises. The after hours rate for use of the existing
       HVAC system is $45.00 per hour during the Term of this Lease. In the
       event Tenant elects to use the HVAC system currently serving the Premises
       after hours, Tenant agrees to notify Landlord at least eight (8) hours
       prior to Tenants need for after hours usage on weekdays and prior to noon
       on Fridays for any weekend usage. At Tenant's sole cost and expense,
       Tenant shall have the right to install and thereafter maintain separate
       self-contained ceiling-mounted HVAC equipment. At Tenant's sole cost and
       expense,

                                                                      Page 5
<PAGE>

       Tenant agrees to install electrical metering for such HVAC equipment and
       thereafter to pay for electrical service provided to such HVAC equipment.

              (b)    Hot and cold water at those points of supply common to all
       floors for lavatory and drinking purposes only twenty-four (24) hours per
       day, 365/366 days per year;

              (c)    Janitor service and periodic window washing in and about
       the Building and the Premises;

              (d)    Elevator service to provide access to and egress from the
       Premises twenty-four (24) hours per day, 365/366 days per year;

              (e)    Electric current twenty-four (24) hours per day, 365/366
       days per year for normal office machines and other machines of low
       electrical consumption (such as typewriters, calculators, photocopiers,
       personal computers, word processors, and specifically including laser
       printers,) and fluorescent lighting (which shall exclude electric current
       for commercial electronic data processing equipment, lighting in excess
       of Building Standard or any other item of electrical equipment which
       singly consumes more than 0.8 kilowatts per hour at rated capacity or
       requires a voltage other than 120 volts single phase). At Tenant's sole
       cost and expense, Tenant shall have the right to submeter electrical
       usage for all or a portion of the Premises, in which event Operating
       Expenses shall be prorated for the usage within the Premises until the
       time such submetering goes into effect, and thereafter shall be prorated
       to reflect any portion of the Premises not included in the submetering
       and normal common area usage charges;

              (f)    Replacement of fluorescent lamps in Building Standard light
       fixtures installed by Landlord and of incandescent bulbs or fluorescent
       lamps in all public restrooms, stairwells and other common areas in the
       Building; and

              (g)    Access control and security services as may from time to
       time be generally standard for comparable buildings in the Quorum,
       Addison, Texas, submarket. NOTWITHSTANDING ANYTHING HEREIN TO THE
       CONTRARY, TENANT EXPRESSLY ACKNOWLEDGES AND AGREES THAT LANDLORD IS NOT
       WARRANTING THE EFFICIENCY OF ANY SUCH SECURITY PERSONNEL, SERVICE,
       PROCEDURES OR EQUIPMENT AND THAT TENANT IS NOT RELYING AND SHALL NOT
       HEREAFTER RELY ON ANY SUCH PERSONNEL, SERVICE, PROCEDURES OR EQUIPMENT.
       LANDLORD SHALL NOT BE RESPONSIBLE OR LIABLE IN ANY MANNER FOR FAILURE OF
       ANY SUCH SECURITY PERSONNEL, SERVICES, PROCEDURES OR EQUIPMENT TO
       PREVENT, CONTROL, OR APPREHEND ANYONE SUSPECTED OF CAUSING PERSONAL
       INJURY OR DAMAGE IN, ON OR AROUND THE COMPLEX. TENANT DOES NOT HEREBY
       WAIVE ANY CLAIMS IT MAY HAVE DIRECTLY AGAINST ANY SUCH SECURITY PROVIDER.

If any of the services described above or elsewhere in this Lease are
interrupted, Landlord shall use reasonable diligence to promptly restore same.
However, neither the interruption or cessation of such services nor the failure
of Landlord to restore same shall render Landlord liable for damages to person
or property, or be construed as an eviction of Tenant, or work an abatement of
Rent or relieve Tenant from fulfilling any of its other obligations hereunder.
Notwithstanding the foregoing, in the event of a material interruption or
failure of services and such material interruption or failure of services
continues for seven (7) consecutive days, rendering the Premises untenantable,
Landlord shall abate the Base Rent on a per

                                                                      Page 6
<PAGE>

them basis retroactive to the first day of such failure and continuing until
such time as such services are restored.

       7.2    KEYS.  Landlord shall furnish Tenant, at Landlord's expense, with
ten (10) keys, and at Tenant's expense with such additional keys as Tenant may
request to unlock each corridor door entering the Premises. Tenant shall not
install, or permit to be installed, any additional lock on any door into or in
the Premises or make, or permit to be made, any duplicates of keys to the
Premises. Landlord shall be entitled at all times to possession of a duplicate
of all keys to all doors to or inside of the Premises. All keys referred to in
this Section 7.2 shall remain the property of Landlord. Upon the expiration or
termination of the Term, Tenant shall surrender all such keys and access cards
to Landlord and shall deliver to Landlord the combination to all locks on all
safes, cabinets and vaults which will remain in the Premises. Landlord shall be
entitled to install, operate and maintain security systems in or about the
Premises and the Complex which monitor, by closed circuit television or
otherwise, all persons leaving or entering the Complex, the Building and the
Premises. Tenant also shall have the right, at its sole cost and expense, to
install and operate such additional access control systems within the Premises
as it shall determine for the purpose of limiting access to or within the
Premises provided Landlord, its agents and employees are provided with
applicable keys and/or codes to the Premises guaranteeing access twenty-four
(24) hours per day, 365/366 days per year.

       7.3    TENANT IDENTITY.  Landlord shall provide and install, in Building
Standard graphics, letters or numerals identifying Tenant's name and suite
number on entrance doors to the Premises. Without Landlord's prior written
consent, no other signs, numerals, letters, graphics, symbols or marks
identifying Tenant shall be placed on the exterior, or on the interior if they
are visible from the exterior, of the Premises. Landlord shall install up to one
(1) directory strip for each ten thousand (10,000) net rentable square feet in
the Premises, listing the names and suite numbers of Tenant on the Building
directory board to be placed in the main lobby of the Building. Tenant shall
have the right, at its sole expense and subject to Landlord's prior written
approval of the design, size, location and method of installation, to install
Tenant's name on the multi-tenant monument sign currently existing at the
Complex. Tenant shall pay to Landlord, within ten (10) days after receipt of an
invoice for same, as Additional Rent, all costs and expenses incurred by
Landlord in connection with installing Tenant's name on such monument sign, and
Tenant's pro rata share (based upon the total number of tenant names included on
such monument sign) of all costs and expenses incurred by Landlord during the
Term of this Lease for the maintenance and repair such monument sign. Subject to
Landlord's prior approval, which approval shall not be unreasonably withheld,
Tenant may install non-Building Standard signage, including Tenant's logo, in
the elevator lobby on any single-tenant floors wholly occupied by Tenant.

       7.4    CHARGES.  Tenant shall pay to Landlord, monthly as billed, as
additional Rent, such charges as may be separately metered or as Landlord may
compute for (a) any utility services utilized by Tenant in excess of that agreed
to be furnished by Landlord pursuant to Section 7.1(e), (b) lighting installed
in the Premises in excess of Building Standard lighting, (c) air-conditioning,
heating and other services in excess of that stated in Section 7.1(a) or
provided at times other than Building Operating Hours and (d) janitorial
services required with respect to Non-Building Standard Items within the
Premises. Landlord may elect to estimate the charges to be paid by Tenant under
this Section 7.4 and bill such charges to Tenant monthly in advance, in which
event Tenant shall promptly pay the estimated charges. When the actual charges
are determined by Landlord an appropriate cash adjustment shall be made between
Landlord and Tenant to account for any underpayment or overpayment by Tenant.
Tenant shall pay all costs associated with providing separate utility meters to
the Leased Premises.

       7.5    OPERATING HOURS.  Subject to Building Rules and Regulations and
such security standards as Landlord may from time to time adopt, the Building
shall be open to the public during the Building Operating Hours and the
Premises shall be open to Tenant twenty-four (24) hours per day, 365/366 days
per year.

                                                                      Page 7
<PAGE>

8.     REPAIR AND MAINTENANCE.

       8.1    BY LANDLORD.  Landlord shall maintain the Building (excluding
leasehold improvements which become fixtures thereto) in a good and operable
condition, and shall make such repairs and replacements as may be required to
maintain the Building in such condition. This Section 8.1 shall not apply to
damage resulting from a Taking (as to which Section 14 shall apply), or damage
resulting from a casualty (as to which Section 15.1 shall apply) or to damage
for which Tenant is otherwise responsible under this Lease. Landlord shall
maintain the Building, all base Building improvements, all mechanical,
electrical and plumbing facilities, subject to the provisions of Section 28.1,
the roof and roof membrane, and the Common Areas in a similar condition to other
office buildings of similar size, age and construction in the Quorum, Addison,
Texas, submarket.

       8.2    BY TENANT. Tenant shall maintain the Premises in a clean, safe,
operable, attractive condition, and will not commit or allow to remain any waste
or damage to any portion of the Premises. Tenant shall repair or replace,
subject to Landlord's direction and supervision, any damage to the Complex
caused by Tenant or Tenant's agents, contractors or invitees. If Tenant fails to
make such repairs or replacements, Landlord may make same at Tenant's cost. Such
cost shall be payable to Landlord by Tenant on demand as additional Rent. All
contractors, workmen, artisans and other persons which or who Tenant proposes to
retain to perform work in the Premises (or the Complex, pursuant to the second
sentence of this Section 8.2) pursuant to this Section 8.2 or Section 11 shall
be approved by Landlord prior to the commencement of any such work.

9.     TAXES ON TENANT'S PROPERTY.  Tenant shall be liable for and shall pay,
before their becoming delinquent, all taxes and assessments levied against any
personal property placed by Tenant in the Premises (even if same becomes a
fixture by operation of law or the property of Landlord by operation of this
Lease), including any additional Impositions which may be assessed, levied,
charged or imposed against Landlord or the Building by reason of Non-Building
Standard Items in the Premises. Tenant may withhold payments of any taxes and
assessments described in this Section 9 so long as Tenant contests its
obligation to pay in accordance with applicable law and the non-payment thereof
does not pose a threat of loss or seizure of the Building or any interest of
Landlord therein.

10.    TRANSFER BY TENANT

       10.1   GENERAL.

              (a)    Without the prior written consent of Landlord (which shall
       not be unreasonably withheld or delayed), Tenant shall not effect or
       suffer any Transfer. Any attempted Transfer without such consent shall be
       void. If Tenant desires to effect a Transfer, it shall deliver to
       Landlord written notice thereof in advance (in accordance with
       subparagraph (b) below) of the date on which Tenant proposes to make the
       Transfer, together with all of the terms of the proposed Transfer and the
       identity of the proposed Transferee. Landlord shall have thirty (30) days
       following receipt of the notice and information within which to notify
       Tenant in writing whether Landlord elects (i) to refuse to consent to the
       Transfer and to terminate this Lease as to the space proposed to be
       Transferred as of the date so specified by Tenant, in which event Tenant
       will be relieved of all further obligations hereunder as to such space;
       however, Landlord will permit occupancy (subject to the terms and
       conditions of this Lease, including, without limitation, Tenant' s
       obligation to pay Rent) of such space by Tenant for ninety (90) days
       following

                                                                      Page 8
<PAGE>

       Landlord's notice of termination provided above, (ii) to refuse to
       consent to the Transfer and to continue this Lease in full force as to
       the entire Premises or (iii) to permit Tenant to effect the proposed
       Transfer. If Landlord fails to notify Tenant of its election within said
       thirty (30) day period, Landlord shall be deemed to have elected option
       (ii). The consent by Landlord to a particular Transfer shall not be
       deemed a consent to any other Transfer. If a Transfer occurs without the
       prior written consent of Landlord as provided herein, Landlord may
       nevertheless collect rent from the Transferee and apply the net amount
       collected to the Rent payable hereunder, but such collection and
       application shall not constitute a waiver of the provisions hereof or a
       release of Tenant from the further performance of its obligations
       hereunder.

              (b)    Landlord and Tenant hereby agree that the granting of
       consent by Landlord, as to those assignments or subleases requiring
       Landlord's consent, shall be preconditioned upon the fulfillment of the
       following requirements of Landlord, as well as any other reasonable
       requirements of Landlord including, without limitation, those set forth
       in Section 10.2 hereof:

                     (1)    Landlord shall be provided with at least twenty (20)
              days written notice prior to any proposed assignment or
              subletting;

                     (2)    The Premises shall remain intact and shall not be
              altered in any manner whatsoever unless Tenant and the prospective
              assignee or sublessee shall pay the entire cost thereof, and
              Landlord's prior written approval is obtained pursuant to Section
              11;

                     (3)    The tangible net worth of the proposed
              subtenant/assignee must be reasonably sufficient for the
              obligations to be assumed by such proposed subtenant/assignee;

                     (4)    Any use of Premises permitted hereunder by the
              proposed sublessee/assignee will not violate or create any
              potential violation of any laws, nor will it violate any other
              agreements affecting the Premises, the Building or Landlord;

                     (5)    The proposed subtenant/assignee will not increase
              traffic congestion above the existing traffic burden generated by
              Tenant's invitees, or create an unreasonable burden on existing
              parking above current parking allowances allocated to Tenant;

                     (6)    Tenant shall pay any and all reasonable attorneys'
              fees or other costs associated with Landlord's review and approval
              of a prospective assignee or sublessee; and

                     (7)    No assignment or sublease shall be to a person or
              entity with whom Landlord is then negotiating, has negotiated
              within the previous six (6) months or currently is a tenant within
              the Building.

       10.2   Conditions. Except as expressly provided below, the following
conditions shall automatically apply to each Transfer, without the necessity of
same being stated in or referred to in Landlord's written consent:

              (a)    Tenant shall execute, have acknowledged and deliver to
       Landlord, and cause the Transferee to execute, have acknowledged and
       deliver to Landlord, an instrument in form and substance acceptable to
       Landlord in which (i) the Transferee adopts this Lease and agrees to

                                                                      Page 9
<PAGE>

       perform, jointly and severally with Tenant, all of the obligations of
       Tenant hereunder, as to the space transferred to it, (ii) the Transferee
       grants Landlord an express first and prior security interest in its
       personal property brought into the transferred space to secure its
       obligations to Landlord hereunder, (iii) Tenant subordinates to
       Landlord's statutory lien and security interest any liens, security
       interests or other rights which Tenant may claim with respect to any
       property of the Transferee, (iv) Tenant agrees with Landlord that, if the
       rent or other consideration due by the Transferee exceeds the Rent for
       the transferred space, then Tenant shall pay Landlord as additional Rent
       hereunder all such excess rent and other consideration immediately upon
       Tenant's receipt thereof after deduction by Tenant of all of the direct
       costs incurred by Tenant in connection with entering into the Transfer,
       reasonable marketing, accounting or legal costs incurred, fees charged by
       Landlord for the cost of any improvements required to prepare the space
       for the Transferee (not to exceed Five Dollars ($5.00) per rentable
       square foot), and reasonable leasing commissions [not to exceed six and
       one-half percent (6 1/2%)]; provided, however, such deduction shall only
       be allowed against such excess rent and not against any portion of the
       Rent, (v) Tenant and the Transferee agree to provide to Landlord, at
       their expense, direct access from a public corridor in the Building to
       the transferred space, (vi) the Transferee agrees to use and occupy the
       transferred space solely for the purpose specified in Section 4 and
       otherwise in strict accordance with this Lease and (vii) Tenant
       acknowledges that, notwithstanding the Transfer, Tenant remains directly
       and primarily liable for the performance of all the obligations of Tenant
       hereunder (including, without limitation, the obligation to pay all
       Rent), and Landlord shall be permitted to enforce this Lease against
       Tenant or the Transferee, or both, without prior demand upon or
       proceeding in any way against any other persons;

              (b)    Tenant may, without the consent of Landlord, Transfer this
       Lease, in whole or in part, to: (i) a corporation into which or with
       which Tenant is wholly merged or consolidated; or (ii) a corporation
       acquiring this Lease and all or substantially all of the other property
       of Tenant and assuming all or substantially all of the liabilities of
       Tenant; or (iii) an entity that acquires all or substantially all of the
       stock or other ownership interests in or of Tenant; or (iv) an Affiliate,
       in which case, no excess consideration will be paid by Tenant to
       Landlord, provided that such Transferee complies with the conditions set
       forth in Section 10.2(a)(i), (ii), (iii), and (vi); and

              (c)    Tenant shall deliver to Landlord a counterpart of all
       instruments relative to the Transfer executed by all parties to such
       transaction (except Landlord).

       10.3   LIENS. Without in any way limiting the generality of the
foregoing, Tenant shall not grant, place or suffer, or permit to be granted,
placed or suffered, against the Complex or any portion thereof, any lien,
security interest, pledge, conditional sale contract, claim, charge or
encumbrance (whether constitutional, contractual or otherwise) and if any of the
aforesaid does arise or is asserted, Tenant will, promptly upon demand by
Landlord and at Tenant's expense, cause same to be released.

11.    ALTERATIONS. Tenant shall not make, or permit to be made, any alteration,
improvement or addition to, or install, or permit to be installed, any fixture
or equipment (other than desk top electrical equipment) in, the Premises without
the prior written consent of Landlord; which in the case of non-structural
alterations, improvements or additions shall not be unreasonably withheld or
delayed by Landlord; provided, however, Tenant shall have the right, without the
prior written consent of Landlord, to make non-structural, cosmetic alterations
with an aggregate cost of less than Ten Thousand Dollars ($10,000.00) provided
that Tenant notifies Landlord at least five (5) business days in advance of the
nature and extent of such proposed alterations, and provided further, that any
such alterations shall be made in a good and workmanlike manner and shall be
made in accordance with the terms and conditions of this Lease and shall not
affect any areas of the

                                                                      Page 10
<PAGE>

Building or the Complex other than the Premises. All such alterations,
improvements and additions shall become the property of Landlord and shall,
at Landlord's election, be (a) surrendered with the Premises as part thereof
at the termination or expiration of the Term, without any payment,
reimbursement or compensation therefor, or (b) removed by Tenant, at Tenant's
expense, with all damage caused by such removal repaired by Tenant.
Landlord's determination of Tenants obligation to remove any such
alterations, improvements and additions shall, within ten (10) business days
following comprehensive submission by Tenant to Landlord, be made by
Landlord, provided adequate specifications as to such alterations,
improvements and additions is submitted with Tenant's notification. Tenant
may remove Tenant's trade fixtures, office supplies, movable office furniture
and equipment provided such removal is made within five days after the
expiration of the Term, no uncured Event of Default exists and Tenant
promptly repairs all damage caused by such removal.

12.    SPECIFICALLY PROHIBITED USES.  Tenant will not (a) use, occupy or permit
the use or occupancy of the Premises for any purpose or in any manner which is
or may be, directly or indirectly, violate of any Legal Requirement, or
dangerous to life or property, or a public or private nuisance or disruptive or
obstructive of any other tenant of the Building, (b) keep, or permit to be kept,
any substance in or conduct, or permit to be conducted, any operation from the
Premises which might emit offensive odors or conditions into other portions of
the Building, or make undue noise or create undue vibrations, (c) commit or
permit to remain any waste to the Premises, (d) install or permit to remain any
improvements to the Premises (other than window coverings which have first been
approved by Landlord) which are visible from the outside of the Premises, or
exceed the structural loads of floors or walls of the Building, or adversely
affect the mechanical, plumbing or electrical systems of the Building or affect
the structural integrity of the Building in any way, (e) install any food, soft
drink or other vending machine (other than those for the exclusive,
non-commercial use of Tenant and its business invitees) in the Premises or (f)
commit, or permit to be committed, any action or circumstance in or about the
Building which, directly or indirectly, would or might justify any insurance
carrier in canceling or increasing the premium on the fire and extended coverage
insurance policy maintained by Landlord on the Building or contents, and if any
increase results from any act of Tenant, then Tenant shall pay such increase
promptly upon demand therefor by Landlord.

13.    ACCESS BY LANDLORD.  Landlord, its employees, contractors, agents and
representatives, shall have the right (and Landlord, for itself and such persons
and firms, hereby reserves the right) to enter the Premises at all hours (a) to
inspect, clean, maintain, repair, replace or alter the Premises or the Building,
(b) to show the Premises to prospective purchasers (or, during the last six (6)
months of the Term, to prospective tenants), (c) to determine whether Tenant is
performing its obligations hereunder and, if it is not, to perform same at
Landlord's option and Tenant's expense or (d) for any other purpose deemed
reasonable by Landlord. In an emergency, Landlord (and such persons and firms)
may use any means to open any door into or in the Premises without any liability
therefor. Entry into the Premises by Landlord or any other person or firm named
in the first sentence of this Section 13 for any purpose permitted herein shall
not constitute a trespass or an eviction (constructive or otherwise), or entitle
Tenant to any abatement or reduction of Rent or constitute grounds for any claim
(and Tenant hereby waives any claim) for damages for any injury to or
interference with Tenant's business, for loss of occupancy or quiet enjoyment or
for consequential damages.

14.    CONDEMNATION.  If all of the Complex is Taken, or if so much of the
Complex is Taken that, in Landlord's reasonable opinion, the remainder cannot be
restored to an economically viable, quality office building, or if the awards
payable to Landlord as a result of any Taking are, in Landlord's reasonable
opinion, inadequate to restore the remainder to an economically viable, quality
office building, Landlord may, at its election, exercisable by the giving of
written notice to Tenant within sixty (60) days after the date of the Taking,

                                                                      Page 11
<PAGE>

terminate this Lease as of the date of the Taking or the date Tenant is
deprived of possession of the Premises (whichever is later). Except in the
case of a temporary Taking, if any portion of the Premises or roof of the
Building shall be the subject of a Taking so as to render any portion of the
Premises unusable for Tenant's business, this Lease shall, at Tenants option,
terminate. If this Lease is not terminated as result of a Taking, Landlord
shall restore the Premises remaining after the Taking to the condition the
Premises were in upon completion of the Landlord's Work, wear and tear and
damages and alterations by the Tenant excepted, such restoration to be
completed by Landlord within two hundred seventy (270) days from the date of
the Taking; provided, however, in the event the Premises have not been
restored to a Building Standard condition within two-hundred seventy (270)
days, Tenant may, at its election, exercisable by the giving of written
notice to Landlord within ten (10) days after the expiration of such two
hundred seventy (270) day period, terminate this Lease. During the period of
restoration, Base Rent shall be abated to the extent the Premises are
rendered untenantable and, after the period of restoration, Base Rent and
Tenant's Share shall be reduced in the proportion that the area of the
Premises Taken or otherwise rendered untenantable bears to the area of the
Premises just prior to the Taking.  All awards, proceeds, compensation or
other payments from or with respect to any taking of the Complex or any
portion thereof shall belong to Landlord, Tenant hereby assigning to Landlord
all of its right, title, interest and claim to same.  Tenant may assert a
claim for and recover from the condemning authority, but not from Landlord,
such compensation as may be awarded on account of Tenant's moving and
relocation expenses, and depreciation to and loss of Tenant's moveable
personal property.

15.    CASUALTY.

       15.1   GENERAL. Tenant shall give prompt written notice to Landlord of
any casualty to the Complex of which Tenant is aware and any casualty to the
Premises. If the Complex or the Premises are totally destroyed, or if the
Complex or the Premises are partially destroyed but in Landlord's opinion, they
cannot be restored to an economically viable, quality office building within two
hundred seventy (270) days from the date of such casualty, or if the insurance
proceeds payable to Landlord as a result of any casualty are, in Landlord's
reasonable opinion, inadequate to restore the portion remaining to an
economically viable and quality office building, Landlord may, at its election
exercisable by the giving of written notice to Tenant within sixty (60) days
after the casualty, terminate this Lease as of the date of the casualty or the
date Tenant is deprived of possession of the Premises (whichever is later). If
this Lease is not terminated as a result of a casualty, Landlord shall (subject
to Section 15.2) restore the Premises to a Building Standard condition;
provided, however, in the event the Premises have not been restored to a
Building Standard condition within two hundred seventy (270) days, Tenant may,
at its election, exercisable by the giving of written notice to Landlord within
ten (10) days after the expiration of such two hundred seventy (270) days
period, terminate this Lease. During the period of restoration, Base Rent shall
be abated to the extent the Premises are rendered untenantable and, after the
period of restoration, Base Rent and Tenant's Share shall be reduced in the
proportion that the area of the Premises remaining tenantable after the casualty
bears to the area of the Premises just prior to the casualty.

       15.2   ACTS OF TENANT.  Notwithstanding any provisions of this Lease to
the contrary, if the Premises or the Complex are damaged or destroyed as a
result of a casualty arising from the acts or omissions of Tenant, or any of
Tenant's officers, directors, shareholders, partners, employees, contractors,
agents, invitees or representatives which constitute gross negligence or willful
misconduct, to the extent not waived pursuant to Section 17.2(a) Tenant's
obligation to pay Rent and to perform its other obligations under this Lease
shall not be abated, reduced or altered in any manner, (b) Landlord shall not be
obligated to repair or restore the Premises or the Complex, and (c) subject to

                                                                      Page 12
<PAGE>

Section 17.2, Tenant shall be obligated, at Tenant's cost, to repair and
restore the Premises or the Complex to the condition they were in just prior
to the damage or destruction under the direction and supervision of, and to
the satisfaction of, Landlord and any Landlord Mortgagee.

16.    SUBORDINATION AND ATTORNMENT.

       16.1   GENERAL. This Lease, Tenant's leasehold estate created hereby and
all of Tenant's rights, titles and interests hereunder and in and to the
Premises are subject and subordinate to any Mortgage presently existing upon all
or any portion of the Complex. However, Landlord and Landlord's Mortgagee may,
at any time upon the giving of written notice to Tenant and without any
compensation or consideration being payable to Tenant, make this Lease, and the
aforesaid leasehold estate and rights, titles and interests, superior to any
Mortgage. Upon the written request by Landlord or by Landlord's Mortgagee to
Tenant, and within five (5) days of the date of such request, and without any
compensation or consideration being payable to Tenant, Tenant shall execute,
have acknowledged and deliver a recordable instrument confirming that this
Lease, Tenant's leasehold estate in the Premises and all of Tenant's rights,
titles and interests hereunder are subject and subordinate (or, at the election
of Landlord or Landlord's Mortgagee, superior) to the Mortgage benefiting
Landlord's Mortgagee. Landlord shall use reasonable efforts to obtain a
non-disturbance agreement reasonably satisfactory to Tenant from all existing
deed of trust lienholders within thirty (30) days following the execution of
this Lease.

       16.2   ATTORNMENT. Upon the written request of any person or party
succeeding to the interest of Landlord under this Lease, Tenant shall
automatically become the tenant of and attorn to such successor in interest
without any change in any of the terms of this Lease. No successor in interest
shall be (a) bound by any payment of Rent for more than one month in advance,
except payments of security for the performance by Tenant of Tenant's
obligations under this Lease, (b) subject to any offset, defense or damages
arising out of a default or any obligations of any preceding Landlord, or (c)
bound by any amendment of this Lease entered into after Tenant has been given
written notice of the name and address of Landlord's Mortgagee and without the
written consent of Landlord's Mortgagee or such successor in interest. The
subordination, attornment and mortgage protection clauses of this Section 16
shall be self-operative and no further instruments of subordination, attornment
or mortgagee protection need be required by any Mortgagee or successor in
interest thereto. Nevertheless, upon the written request therefor and without
any compensation or consideration being payable to Tenant, Tenant agrees to
execute, have acknowledged and deliver such instruments as may be requested to
confirm the same. Notwithstanding the foregoing, any instrument of
subordination, attornment and non-disturbance shall be satisfactory to
Landlord's Mortgagee, its successors and assigns.

17.    INSURANCE

       17.1   GENERAL. Tenant shall obtain and maintain throughout the Term the
following policies of insurance:

              (a)    fire and all risk insurance, with vandalism, malicious
       mischief and sprinkler leakage endorsements, on all of Tenant's personal
       property located in, and on all Non-Building Standard Items to, the
       Premises in an amount not less than eighty percent (80%) of the
       replacement cost thereof;

              (b)    comprehensive general and contractual liability insurance
       against claims for personal injury, bodily injury, death and property
       damage occurring in or about the Premises, such insurance to afford
       protection to the limits of not less than $ 1,000,000 per occurrence;

                                                                      Page 13
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              (c)    insurance required hereunder shall be written by companies
       licensed to do business in the State of Texas and shall have a minimum
       rating of A:VIII by Best's Key Rating Guide; and

              (d)    such other policy or policies of insurance as Landlord may
       reasonably require.

Tenant shall deliver to Landlord, prior to the Commencement Date, certificates
of such insurance and shall, at all times during the Term, deliver to Landlord
upon request true copies of such insurance policies. The policy described in
clause (b) shall (i) name Landlord as an addition insured, (ii) provide that it
will not be canceled, reduced or non-renewed without thirty (30) days' prior
written notice to Landlord, (iii) insure performance of the indemnities of
Tenant contained in Section 18 and elsewhere in this Lease and (iv) be primary
coverage, so that any insurance coverage obtained by Landlord shall be in excess
thereto. Tenant shall deliver to Landlord certificates of renewal at least
thirty (30) days before the expiration date of each such policy and copies of
new policies at least thirty (30) days before terminating any such policies. All
policies of insurance required to be obtained and maintained by Tenant shall be
subject to the approval of Landlord as to terms, coverage, deductibles and
issuer.

       17.2   WAIVER OF SUBROGATION.  LANDLORD AND TENANT HEREBY WAIVE ALL
CLAIMS, RIGHTS OF RECOVERY AND CAUSES OF ACTION THAT EITHER PARTY OR ANY PARTY
CLAIMING BY, THROUGH OR UNDER SUCH PARTY MAY NOW OR HEREAFTER HAVE BY
SUBROGATION OR OTHERWISE AGAINST THE OTHER PARTY OR AGAINST ANY OF THE OTHER
PARTY'S OFFICERS, DIRECTORS, SHAREHOLDERS, PARTNERS OR EMPLOYEES FOR ANY LOSS OR
DAMAGE THAT MAY OCCUR TO THE COMPLEX, THE PREMISES, TENANT'S IMPROVEMENTS OR ANY
OF THE CONTENTS OF ANY OF THE FOREGOING BY REASON OF FIRE OR OTHER CASUALTY, OR
BY REASON OF ANY OTHER CAUSE (THUS INCLUDING SIMPLE NEGLIGENCE OF THE PARTIES
HERETO OR THEIR OFFICERS, DIRECTORS, SHAREHOLDERS, PARTNERS OR EMPLOYEES), THAT
COULD HAVE BEEN INSURED AGAINST UNDER THE TERMS OF (A) IN THE CASE OF LANDLORD,
THE STANDARD FIRE AND EXTENDED COVERAGE INSURANCE POLICIES AVAILABLE IN THE
STATE WHERE THE COMPLEX IS LOCATED AT THE TIME OF THE CASUALTY AND (B) IN THE
CASE OF TENANT, THE FIRE AND EXTENDED COVERAGE INSURANCE POLICY REQUIRED TO BE
OBTAINED AND MAINTAINED UNDER SECTION 17.1. LANDLORD AND TENANT SHALL CAUSE AN
ENDORSEMENT TO BE ISSUED TO THEIR RESPECTIVE INSURANCE POLICIES RECOGNIZINGTHIS
WAIVER OF SUBROGATION.

       17.3   LANDLORD'S INSURANCE. Landlord, at all times during the term of
this Lease, shall insure the Building (excluding any property which Tenant is
obligated to insure under Section 17.1 hereof) against damage with all risk
insurance (with replacement cost coverage) and comprehensive general public
liability insurance, all in such amounts, and with such deductibles as are
obtained by similarly situated landlords of office buildings comparable to the
Building in the Quorum, Addison, Texas, submarket from time to time, including
eighty percent (80%) replacement cost with twelve (12) months rent loss
coverage. Notwithstanding any contribution by Tenant to the cost of insurance
premiums, as provided in this Lease, Tenant acknowledges that it has no right to
receive any proceeds from any insurance policies carried by Landlord. Annually,
upon the request of Tenant, a copy of a duly executed certificate of insurance
reflecting Landlord's maintenance of the insurance required under this Section
shall be delivered to Tenant.

18.    INDEMNITY.  SUBJECT TO SECTION 17.2, TENANT SHALL DEFEND, INDEMNIFY AND
HOLD HARMLESS LANDLORD AND LANDLORD'S OFFICERS, DIRECTORS, SHAREHOLDERS,

                                                                      Page 14
<PAGE>

PARTNERS AND EMPLOYEES FROM AND AGAINST, ALL LIABILITIES, OBLIGATIONS,
LOSSES, DAMAGES, PENALTIES, CLAIMS, ACTIONS, SUITS, COSTS, EXPENSES AND
DISBURSEMENTS (INCLUDING COURT COSTS AND REASONABLE ATTORNEYS' FEES) RESULTING
FROM ANY INJURIES TO OR DEATH OF ANY PERSON OR DAMAGE TO ANY PROPERTY
OCCURRING DURING THE TERM IN OR ABOUT THE PREMISES. TENANT SHALL NOT BE
OBLIGATED TO INDEMNIFY LANDLORD AGAINST, AND TENANT DOES NOT WAIVE ANY CLAIMS
ARISING OUT OF, LANDLORD'S GROSS NEGLIGENCE OR WILLFUL MISCONDUCT. LANDLORD
WILL INDEMNIFY AND HOLD TENANT HARMLESS FROM AND AGAINST ANY CLAIMS, LOSSES,
DEMANDS, LIABILITIES, DAMAGES, AND EXPENSES (INCLUDING LEGAL FEES) RESULTING
FROM ANY INJURIES TO OR DEATH OF ANY PERSON OR DAMAGE TO ANY PROPERTY
OCCURRING DURING THE TERM IN OR ABOUT THE PREMISES, BUILDING OR COMPLEX
CAUSED BY THE GROSS NEGLIGENCE OR WILLFUL MISCONDUCT OF LANDLORD, ITS AGENTS,
SERVANTS, AND EMPLOYEES.

19.    THIRD PARTIES; ACTS OF FORCE MAJEURE. Landlord shall have no liability to
Tenant or to Tenant's officers, directors, shareholders, partners, employees,
agents, contractors or invitees, for bodily injury, death, property damage,
business interruption, loss of profits, loss of trade secrets or other direct or
consequential damages occasioned by (a) the acts or omissions of any other
tenant or such other tenant's officers, directors, shareholders, partners,
employees, agents, contractors or other invitees within the Complex, (b) Force
Majeure, (c) vandalism, theft, burglary and other criminal acts (other than
those committed by Landlord and its employees), (d) water leakage, or (e) the
repair, replacement, maintenance, damage, destruction or relocation of the
Premises, except if caused by Landlord's gross negligence or willful misconduct.
Nothing contained herein shall limit Landlord's obligations under this Lease,
such as repair and maintenance.

20.    SECURITY INTEREST.  As security for Tenant's payment of Rent and
performance of all of its other obligations under this Lease, Tenant hereby
grants to Landlord a security interest in all fixtures, furniture, phones,
computers and equipment of Tenant now or hereafter placed in the Premises. In no
event shall the security interest apply to customer files, or books or records.
Landlord, as secured party, shall be entitled to all of the rights, remedies and
recourses afforded to a secured party under the Texas Uniform Commercial Code,
which rights, remedies and recourses shall be cumulative of all other rights,
remedies, recourses, liens and security interests afforded Landlord by law,
equity or this Lease. Contemporaneously with the execution of this Lease, Tenant
shall execute and deliver, as debtor, promptly upon request and without any
compensation or consideration being payable to Tenant, such additional financing
statement or statements as Landlord may request. However, Landlord may at any
time file a copy of this Lease as a financing statement. So long as no Event of
Default exists and upon five (5) days' prior written notice to Landlord, Tenant
shall have the right to remove less than all or substantially all of its
personal property from the Premises without Landlord's approval, including
telephones, satellite dishes and related equipment and cabling. The foregoing
security interest shall commence simultaneously with the expiration of the
Letter of Credit described in Section 28.2, however brought about, and
thereafter remain in effect.

21.    CONTROL OF COMMON AREAS.  Subject to the terms of Section 28.1, Landlord
shall have the exclusive control over the Common Areas. Landlord may, from time
to time, create different Common Areas, close or otherwise modify the Common
Areas, and modify the Building Rules and Regulations with respect thereto.

22.    INTENTIONALLY DELETED.

                                                                      Page 15
<PAGE>

23.    QUIET ENJOYMENT.  Provided Tenant is not in default beyond any applicable
notice and cure periods, if curable, under this Lease, Tenant shall and may
peaceably and quietly have, hold, occupy, use and enjoy the Premises during the
Term subject to the provisions of this Lease. Landlord shall warrant and forever
defend Tenant's right to occupancy of the Premises against the claims of any and
all persons whomsoever lawfully claiming the same or any part thereof, by,
through or under Landlord, but not otherwise, subject to the provisions of this
Lease.

24.    DEFAULT BY TENANT.

       24.1   EVENTS OF DEFAULT. Each of the following occurrences shall
constitute an Event of Default (herein so called):

              (a)    The failure of Tenant to pay Rent as and when due hereunder
       and the continuance of such failure for a period of five (5) days after
       written notice from Landlord to Tenant specifying the failure; provided,
       however, after Landlord has given Tenant written notice pursuant to this
       clause (a) on two (2) separate occasions in any single calendar year,
       Landlord shall not be required to give Tenant any further notice under
       this clause (a);

              (b)    The failure of Tenant to perform, comply with or observe
       any other agreement, obligation or undertaking of Tenant, or any other
       term, condition or provision, in this Lease, and the continuance of such
       failure for a period of thirty (30) days after written notice from
       Landlord to Tenant specifying the failure and such additional time [but
       not to exceed ninety (90) days after such written notice from Landlord to
       Tenant], if any, as is reasonably necessary to cure such failure if such
       failure is of such a nature that it cannot reasonably be cured within
       such thirty (30) day period, provided that Tenant commences the curing of
       the same within such thirty (30) day period and diligently and
       continuously prosecutes the curing of the same in good faith and with due
       diligence;

              (c)    The failure of Tenant to accept and move into the Premises
       following satisfaction by Landlord of the provisions contained in EXHIBIT
       D passage of the Commencement Date and Tenant's failure to enter into the
       Commencement Date agreement pursuant to Section 6.3 within thirty (30)
       days following submission thereof to Tenant by Landlord;

              (d)    The filing of a petition by or against Tenant (the term
       "Tenant" also meaning, for the purpose of this clause (d), any guarantor
       of the named Tenant's obligations hereunder) (i) in any bankruptcy or
       other insolvency proceeding, (ii) seeking any relief under the Bankruptcy
       Code or any similar debtor relief law, (iii) for the appointment of a
       liquidator or receiver for all or substantially all of Tenant's property
       or for Tenant's interest in this Lease or (iv) to reorganize or modify
       Tenant's capital structure (and, in the event that such petition is filed
       against Tenant, that petition is not removed or set aside within sixty
       (60) days from the filing date thereof); and

              (e)    The admission by Tenant in writing that it cannot meet its
       obligations as they become due or the making by Tenant of an assignment
       for the benefit of its creditors.

       24.2   REMEDIES OF LANDLORD.  Upon any Event of Default, Landlord may, at
Landlord's option and in addition to all other rights, remedies and recourses
afforded Landlord hereunder or by law or equity, do any one or more of the
following:

              (a)    Terminate this Lease by the giving of written notice to
       Tenant, in which event Tenant shall pay to Landlord the sum of (i) all
       Rent and other amounts accrued hereunder to the

                                                                      Page 16
<PAGE>

       date of termination, (ii) all amounts due under Section 24.3 and (iii)
       liquidated damages in an amount equal to (A) the total Rent that
       Tenant would have been required to pay for the remainder of the Term
       discounted to present value at the prime lending rate (or equivalent
       rate, however denominated) in effect on the date of termination at the
       largest national bank in the state where the Complex is located minus
       (B) the then present fair rental value of the Premises for such
       period, similarly discounted.

              (b)    Terminate Tenant's right to possession of the Premises
       without terminating this Lease by the giving of written notice to Tenant,
       in which event Tenant shall pay to Landlord (i) all Rent and other
       amounts accrued hereunder to the date of termination of possession, (ii)
       all amounts due from time to time under Section 24.3 and (iii) all Rent
       and other sums required hereunder to be paid by Tenant during the
       remainder of the Term, diminished by any net sums thereafter received by
       Landlord through reletting the Premises during said period. Reentry by
       Landlord in the Premises will not affect the obligations of Tenant
       hereunder for the unexpired Term. Landlord may bring action against
       Tenant to collect amounts due by Tenant on one or more occasions, without
       the necessity of Landlord's waiting until expiration of the Term. If
       Landlord elects to proceed under this Section 24.2(b), it may at any time
       elect to terminate this Lease pursuant to Section 24.2(a).

              (c)    Without notice, alter any and all locks and other security
       devices at the Premises without being obligated to deliver new keys to
       the Premises, unless Tenant has cured all Events of Default before
       Landlord has terminated this Lease under Section 24.2(a) or has entered
       into a lease to relet all or a portion of the Premises.

              (d)    If an Event of Default specified in Section 24.1 (c)
       occurs, Landlord may remove and store any property that remains on the
       Premises, and, if Tenant does not claim such property within ten (10)
       days after Landlord has delivered to Tenant notice of such storage,
       Landlord may appropriate, sell, destroy, or otherwise dispose of the
       property in question without notice to Tenant or any other person and
       without any obligation to account for such property.

       24.3   PAYMENT BY TENANT. Upon any Event of Default, Tenant shall also
pay to Landlord all costs and expenses incurred by Landlord, including court
costs and reasonable attorneys' fees, in (a) retaking or otherwise obtaining
possession of the Premises, (b) removing and storing Tenant's or any other
occupant's property, (c) repairing, restoring, altering, remodeling or otherwise
putting the Premises into condition acceptable to a new tenant or tenants (which
amount Landlord agrees shall not exceed $12.00 per square foot), (d) reletting
all or any part of the Premises, (e) paying or performing the underlying
obligation which Tenant failed to pay or perform and (f) enforcing any of
Landlord's rights, remedies or recourses arising as a consequence of the Event
of Default.

       24.4   RELETTING.  Upon termination of this Lease or upon termination of
Tenant's right to possession of the Premises, Landlord shall use reasonable
efforts to relet the Premises on such terms and conditions as Landlord in its
sole discretion may determine (including a term different than the Term, rental
concessions, and alterations to, and improvements of, the Premises); however,
Landlord shall not be obligated to relet the Premises before leasing other
portions of the Building. Landlord shall not be liable, nor shall Tenant's
obligations hereunder be diminished because of, Landlord's failure to relet the
Premises or collect rent due in respect of such reletting. Tenant shall not be
entitled to the excess of any rent obtained by reletting over the Rent herein
reserved.

       24.5   LANDLORD'S RIGHT TO PAY OR PERFORM. Upon an Event of Default,
Landlord may, but without obligation to do so and without thereby waiving or
curing such Event of Default, pay or perform

                                                                      Page 17
<PAGE>

the underlying obligation for the account of Tenant, and enter the Premises
and expend the Security Deposit for such purpose.

       24.6   NO WAIVER.  No Implied Surrender, Provisions of this Lease may
only be waived by the party entitled to the benefit of the provision evidencing
the waiver in writing. Thus, neither the acceptance of Rent by Landlord
following an Event of Default (whether known to Landlord or not), nor any other
custom or practice followed in connection with this Lease, shall constitute a
waiver by Landlord of such Event of Default or any other Event of Default.
Further, the failure by Landlord to complain of any action or inaction by
Tenant, or to assert that any action or inaction by Tenant constitutes (or would
constitute, with the giving of notice and the passage of time) an Event of
Default, regardless of how long such failure continues, shall not extinguish,
waive or in any way diminish the rights, remedies and recourses of Landlord with
respect to such action or inaction. No waiver by Landlord of any provision of
this Lease or of any breach by Tenant of any obligation of Tenant hereunder
shall be deemed to be a waiver of any other provision hereof, or of any
subsequent breach by Tenant of the same or any other provision hereof.
Landlord's consent to any act by Tenant requiring Landlord's consent shall not
be deemed to render unnecessary the obtaining of Landlord's consent to any
subsequent act of Tenant. No act or omission by Landlord (other than Landlord's
execution of a document acknowledging such surrender) or Landlord's agents,
including the delivery of the keys to the Premises, shall constitute an
acceptance of a surrender of the Premises.

25.    DEFAULTS BY LANDLORD.  Landlord shall not be in default under this Lease,
and Tenant shall not be entitled to exercise any right, remedy or recourse
against Landlord or otherwise as a consequence of any alleged default by
Landlord under this Lease, except as expressly set forth herein, unless Landlord
fails to perform any of its obligations hereunder and said failure continues for
a period of thirty (30) days after Tenant gives Landlord and (provided that
Tenant shall have been given the name and address of Landlord's Mortgagee)
Landlord's Mortgagee written notice thereof specifying, with reasonable
particularity, the nature of Landlord's failure. If, however, the failure cannot
reasonably be cured within the thirty (30) day period, Landlord shall not be in
default hereunder if Landlord or Landlord's Mortgagee commences to cure the
failure within the thirty (30) days and thereafter pursues the curing of same
diligently to completion. If Tenant recovers a money judgment against Landlord
for Landlord's default of its obligations hereunder or otherwise, the judgment
shall be limited to Tenant's actual direct, but not consequential, damages
therefor and shall be satisfied only out of the interest of Landlord in the
Complex as the same may then be encumbered, and Landlord shall not otherwise be
liable for any deficiency. In no event shall Tenant have the right to levy
execution against any property of Landlord other than its interest in the
Complex. The foregoing shall not limit any right that Tenant might have to
obtain specific performance of Landlord's obligations hereunder.

26.    RIGHT OF REENTRY.  Upon the expiration or termination of the Term for
whatever cause, or upon the exercise by Landlord of its right to re-enter the
Premises without terminating this Lease, Tenant shall immediately, quietly and
peaceably surrender to Landlord possession of the Premises in "broom clean" and
good order, condition and repair, except only for ordinary wear and tear, damage
by casualty not covered by Section 15.2 and repairs to be made by Landlord
pursuant to Section 15.1. If Tenant fails to surrender possession as herein
required, Landlord may, without giving Tenant prior notice to vacate the
Premises or any other notice, initiate any and all legal action as Landlord may
elect to dispossess Tenant and all of its property, and all persons or firms
claiming by, through or under Tenant and all of their property, from the
Premises, and may remove from the Premises and store (without any liability for
loss, theft, damage or destruction thereto) any such property at Tenant's cost.
While Tenant remains in possession of the Premises after such expiration,
termination or exercise by Landlord of its re-entry right, Tenant shall be
deemed to be occupying tile Premises as a tenant-at-sufferance, subject to all
of the obligations of Tenant under this Lease, except that the daily Rent shall

                                                                      Page 18
<PAGE>

be twice the per day Rent in effect immediately before such expiration,
termination or exercise by Landlord; provided, that if Tenant provides notice
to Landlord no less than six (6) months prior to the scheduled expiration
date of this Lease that Tenant desires to holdover for a term of six (6)
months, then the daily rent shall be one hundred seventy-five percent (175%)
of the per day rent in effect immediately before such expiration, termination
or exercise by Landlord, and Tenant shall be entitled to holdover for a
period not to exceed six (6) months. No such holding over shall extend the
Term and no further notice to Landlord by Tenant shall extend Tenant's
permitted occupancy of the Premises. If Tenant fails to surrender possession
of the Premises in the condition herein required, Landlord may, at Tenant's
expense, restore the Premises to such condition.

27.    MISCELLANEOUS.

       27.1   INDEPENDENT OBLIGATIONS. The obligations of Tenant to pay Rent
and to perform the other undertakings of Tenant hereunder constitute
independent unconditional obligations to be performed at the times specified
hereunder, regardless of any breach or default by Landlord hereunder. Tenant
shall have no right, and Tenant hereby waives and relinquishes all rights
which Tenant might otherwise have, to claim any nature of lien against the
Complex or, except as otherwise expressly provided for herein, to withhold,
deduct from or offset against any Rent or other sums to be paid to Landlord
by Tenant.

       27.2   TIME OF ESSENCE.  Time is of the essence with respect to each date
or time specified in this Lease by which an event is to occur.

       27.3   APPLICABLE LAW.  THIS LEASE SHALL BE GOVERNED BY AND CONSTRUED IN
ACCORDANCE WITH THE LAWS OF THE STATE OF TEXAS. ALL MONETARY AND OTHER
OBLIGATIONS OF LANDLORD AND TENANT ARE PERFORMABLE IN THE COUNTY WHERE THE
COMPLEX IS LOCATED.

       27.4   ASSIGNMENT BY LANDLORD.  Landlord shall have the right to assign,
in whole or in part, any or all of its rights, titles or interests in and to the
Complex or this Lease and, upon any such assignment, (i) Landlord shall be
relieved of all unaccrued liabilities and obligations hereunder to the extent of
the interest so assigned, and (ii) to the extent assignable, Landlord shall
assign the Letter of Credit described in Section 28 or any Security Deposit
remaining hereunder to its successors and assigns. To the extent the Letter of
Credit described in Section 28.2 is not assignable, Tenant will cooperate
promptly to secure a replacement Letter of Credit issued for the benefit of
Landlord's successors and assigns.

       27.5   COMMENCEMENT DATE AND ESTOPPEL CERTIFICATES.  From time to time at
the request of Landlord or Landlord's Mortgagee, Tenant will promptly and
without compensation or consideration execute, have acknowledged and deliver a
certificate stating (a) the Commencement Date and the date of expiration of the
Term, (b) the rights (if any) of Tenant to extend the Term or to expand the
Premises, (c) the Rent (or any components of the Rent) currently payable
hereunder, (d) whether this Lease has been amended in any respect and, if so,
submitting copies of or otherwise identifying the amendments, (e) whether,
within the knowledge of Tenant, there are any existing breaches or defaults by
Landlord hereunder and, if so, stating the defaults with reasonable
particularity and (f) such other information pertaining to this Lease as
Landlord or Landlord's Mortgagee may reasonably request.

       27.6   SIGNS, BUILDING NAME AND BUILDING ADDRESS.  Landlord may, from
time to time at its discretion, maintain any and all signs anywhere in the

                                                                      Page 19
<PAGE>

Complex, and to change the name and street address of the Complex. Tenant
shall not use the name of the Building for any purpose other than as the
address of the business to be conducted by Tenant from the Premises.

       27.7   NOTICES.  All notices and other communications given pursuant to
this Lease shall be in writing and shall either be mailed by first class United
States mail, postage prepaid, registered or certified with return receipt
requested, and addressed as set forth in this Section 27.7, or delivered in
person to the intended addressee, or sent by prepaid telegram, cable or telex
followed by a confirmatory letter. Notice mailed in the aforesaid manner shall
become effective three (3) business days after deposit; notice given in any
other manner, and any notice given to Landlord, shall be effective only upon
receipt by die intended addressee. Each party shall have the continuing right to
change its address for notice hereunder by the giving of fifteen (15) days'
prior written notice to the other party in accordance with this Section 27.7.
All payments should be made payable to CarrAmerica Realty, L. P. t/a Quorum
Place and delivered to P.O. Box 100899, Atlanta, Georgia 30384-0899, or wired to
CarrAmerica Realty, L.P. t/a Quorum Place, Acct. No. 3255807887, ABA#
061-000-0052 at NationsBank of Georgia.

              Landlord:
              CarrAmerica Realty, L.P.
              14901 Quorum Drive, Suite 180
              Dallas, Texas 75240
              Attn: Property Manager

              With a copy to:
              CarrAmerica Realty, L.P.
              1700 Pennsylvania Avenue, N.W.
              Suite 700
              Washington, DC 20006
              Attn: Lease Administration

              Tenant:
              ObjectSpace, Inc.
              14881 Quorum Drive, Suite 400
              Dallas, Texas 75240
              Attn: John W. Pritchett, Chief Financial Officer

       27.8   ENTIRE AGREEMENT, AMENDMENT AND BINDING EFFECT.  This Lease
constitutes the entire agreement between Landlord and Tenant relating to the
subject matter hereof and all prior agreements relative hereto which are not
contained herein are terminated. This Lease may be amended only by a written
document duly executed by Landlord and Tenant (and, if a Mortgage is then in
effect, by the Landlord's Mortgagee entitled to the benefits thereof), and any
alleged amendment which is not so documented shall not be effective as to either
party. The provisions of this Lease shall be binding upon and inure to the
benefit of the parties hereto and their heirs, executors, administrators,
successors and assigns; provided, however, that this Section 27.8 shall not
negate, diminish or alter the restrictions on Transfers applicable to Tenant set
forth elsewhere in this Lease.

       27.9   SEVERABILITY.  This Lease is intended to be performed in
accordance with and only to the extent permitted by all Legal Requirements. If
any provision of this Lease or the application thereof to any person or
circumstance shall, for any reason and to any extent, be invalid or
unenforceable, but the extent of the invalidity or unenforceability does not
destroy the basis of the bargain between the parties as contained herein, the
remainder of this Lease and the application of such provision to other

                                                                      Page 20
<PAGE>

persons or circumstances shall not be affected thereby, but rather shall be
enforced to the greatest extent permitted by law.

       27.10  NUMBER AND GENDER, CAPTIONS AND REFERENCES.  As the context of
this Lease may require, pronouns shall include natural persons and legal
entities of every kind and character, the singular number shall include the
plural and the neuter shall include the masculine and the feminine gender.
Section headings in this Lease are for convenience of reference only and are not
intended, to any extent and for any purpose, to limit or define any section
hereof. Whenever the terms "hereof", "hereby", "herein", "hereunder" or words of
similar import are used in this Lease, they shall be construed as referring to
this Lease in its entirety rather than to a particular section or provision,
unless the context specifically indicates to the contrary. Any reference to a
particular "Section" shall be construed as referring to the indicated section of
this Lease.

       27.11  ATTORNEYS' FEES.  If either party hereto initiates any litigation
against the other party relating to this Lease, the prevailing party shall be
entitled to recover, in addition to all damages allowed by law and other relief,
all court costs and reasonable attorneys' fees incurred in connection with such
litigation.

       27.12  BROKERS.  Tenant and Landlord hereby warrant and represent unto
the other that it has not incurred or authorized any brokerage commission,
finder's fees or similar payments in connection with this Lease, other than that
which is due to Glenhurst Realty Advisors, Inc. and The Staubach Company, which
payment shall be paid Landlord. Each party shall defend, indemnify and hold the
other harmless from and against any claim for brokerage commission, finder's
fees or similar payment arising by virtue of authorization of such party, or any
Affiliate of such party, in connection with this Lease.

       27.13  INTEREST ON TENANT'S OBLIGATIONS.  Following the lapse of any
applicable cure periods set forth herein, any amount due from Tenant to Landlord
which is not paid when due shall bear interest at the maximum rate allowed by
law from the date such payment is due until paid, but the payment of such
interest shall not excuse or cure the default in payment.

       27.14  AUTHORITY.  Tenant warrants and represents to Landlord that (a)
Tenant is a duly organized and existing legal entity, in good standing in the
State of Texas, (b) Tenant has full right and authority to execute, deliver and
perform this Lease, (c) the person executing this Lease on behalf of Tenant was
authorized to do so and (d) upon request of Landlord, such person will deliver
to Landlord satisfactory evidence of his or her authority to execute this Lease
on behalf of Tenant.

       27.15  RECORDING.  Neither this Lease (including any Exhibit hereto) nor
any memorandum hereof shall be recorded without the prior written consent of
Landlord.

       27.16  EXHIBITS.  All Exhibits and written addenda hereto are
incorporated herein for any and all purposes.

       27.17  MULTIPLE COUNTERPARTS.  This Lease may be executed in two or more
counterparts, each of which shall be an original, but all of which shall
constitute but one instrument.

                                                                      Page 21
<PAGE>

28.    SPECIAL PROVISIONS

       28.1   ROOF RIGHTS.

              (a)    Tenant shall have the non-exclusive right to install,
       operate, and maintain at its sole expense, a maximum of one (1) 6-foot
       satellite dish and other related equipment, which related equipment shall
       not exceed thirty (30) pounds (collectively, the "Communications
       Equipment"), in an area on the roof of the Building designated by
       Landlord, which area shall be encompassed by a four foot (4') radius
       measured from the center of such Communications Equipment (the "Roof
       Space"), to use in connection with Tenant's business in the Premises;
       provided, however, that none of such installations of Communications
       Equipment may be visible at the ground level in the vicinity of the
       Building. Tenant's use of the Roof Space pursuant to this Section will be
       without charge to Tenant during the Lease Term.

              (b)    Tenant shall have access to the roof and Tenant's equipment
       relating to the Communications Equipment at all times throughout the
       Lease Term, such right to be limited to authorized engineers of Tenant or
       persons under Tenant's direct supervision and subject to the Building
       Rules and Regulations. During normal business hours (for purposes hereof,
       between 8:00 a.m. and 5:00 p.m., Monday through Friday), Tenant must
       notify Building personnel of Tenant's need to gain access to the Building
       roof Building personnel must escort Tenant to the roof access. During
       requested after-hours access, Tenant's personnel must be accompanied by
       Building personnel and Tenant will be billed at a rate of $35.00 per hour
       for scheduled maintenance with a three (3) hour minimum for unscheduled
       call-backs.

              (c)    Tenant's Communications Equipment, and the associated
       wiring thereto, shall be installed in accordance with plans and
       specifications approved by Landlord by contractors selected and employed
       by Tenant. The installation, operation and maintenance of Tenant's
       Communications Equipment will in no way damage the Building, interfere
       with users already on or in the Premises, or interfere with Landlord's
       maintenance of the Premises. Tenant shall cause all of Tenant's
       communications from the roof of the Building and Tenant's Communications
       Equipment to comply with Legal Requirements. Landlord and its
       representatives agree to cooperate with Tenant in connection with
       obtaining satellite permits, licenses, zoning variances, special use
       permits or other authorizations necessary for Tenants use of the
       above-described satellite dishes, provided that such permits, licenses,
       variances or special use permits do not increase Landlord's obligations
       hereunder or thereunder, and Landlord shall not be required to expend any
       money in connection therewith. Electrical power will be supplied by
       Landlord and paid for by Tenant. All work relating to the Communications
       Equipment shall be coordinated with Landlord's roofing contractor so as
       not to adversely affect any warranties in respect of the roof. The
       maintenance and operation of Tenant's Communications Equipment shall be
       accomplished at Tenant's sole expense by Tenant or contractors selected
       and employed by Tenant.

              (d)    Landlord will not be liable for the failure of Tenant's
       Communications Equipment to work, regardless of the cause of such
       failure; nor shall Landlord be liable for any interference with the
       reception of the antennas that may result from future construction in or
       around the Building. Landlord will not be liable for any failure of the
       Communications Equipment or the functionality thereof due to temporary
       interruptions of electricity and/or routine Building maintenance and
       repairs. Prior to allowing any other tenant to install equipment on the
       roof within a ten foot (10') radius from the center of Tenant's existing
       Communications Equipment, Landlord agrees to consult with Tenant to
       ensure the functionality of Tenant's Communications Equipment is not
       diminished by such additional installation. Landlord reserves the right
       to require Tenant to relocate the Communications Equipment a maximum of
       two (2) times during the Term, provided there is adequate space on the
       roof of the Building which will not diminish the functionality of
       Tenant's Communications Equipment. In the event the relocation

                                                                      Page 22
<PAGE>

       of the Communications Equipment is required to accommodate another tenant
       Landlord agrees to reimburse Tenant for the actual cost of such
       relocation and any repairs required at the original Roof Space to restore
       same to its original condition.

              (e)    Tenant agrees that its indemnification of Landlord
       contained in Section 18 shall also apply to the Roof Space and
       Communications Equipment. Furthermore Tenant agrees that the insurance
       requirements described in Section 17 shall also apply to the Roof Space
       and Communications Equipment.

              (f)    Any Communications Equipment installed on the roof by
       Tenant and any connecting wiring to the Premises shall remain Tenant's
       property notwithstanding attachment to the Building, may be removed by
       Tenant at any time, and shall be removed by Tenant at the conclusion of
       the Lease Term with Tenant restoring any damage to the Roof Space, or
       elsewhere in or on the Building, which may have been caused by the
       installation or its removal. Transfers to Tenant's Affiliates of
       ownership in and/or use of the Communications Equipment shall be governed
       by the provisions of Section 10.

       28.2   SECURITY DEPOSIT: LETTER OF CREDIT.  To secure payment and
performance of Tenant's obligations under this Lease, Tenant shall cause an
irrevocable, unconditional Letter of Credit (the "Letter of Credit") in an
amount equal to Five Hundred Seventy-Four Thousand Nine Hundred Thirteen and
72/100 Dollars ($574,913.72) in form and substance satisfactory to Landlord from
a financial institution acceptable to Landlord in its discretion to be issued to
and naming Landlord as the beneficiary within five (5) days of the execution
date of this Lease. Tenant's failure to deliver the Letter of Credit as provided
above shall, at Landlord's election, cause this Lease to terminate and neither
Landlord nor Tenant shall have any further obligations hereunder; it being
understood that the construction contemplated in the Work Letter, and any
preparation therefor on Landlord's part, will not commence until Landlord has
received such Letter of Credit. The initial term of the Letter of Credit shall
be for the period commencing on the execution date of this Lease and expiring on
the first (1st) anniversary of such execution date. Thereafter, the Letter of
Credit shall be automatically extended, with notice thereof forwarded to
Landlord by the issuer of such Letter of Credit no less than twenty (20) days
prior to the scheduled expiration date for such Letter of Credit, for two (2)
successive one (1) year terms. Landlord shall have the right to immediately
present the Letter of Credit for payment upon an Event of Default or in the
event the original Letter of Credit or the first renewal thereof are not
automatically renewed on or before twenty (20) days from their respective
expiration dates. Notwithstanding anything contained herein to the contrary,
Tenant shall be entitled to request that Landlord substitute a new letter of
credit for the existing Letter of Credit from time to time but not more often
than once per month, which new letter of credit shall be in form and substance
satisfactory to Landlord from a financial institution acceptable to Landlord in
its discretion and expiring on the same date as the Letter of Credit. The
aggregate amount of the new letter of credit may be decreased by an amount equal
to Twenty-Five Thousand Dollars ($25,000.00) per month for each month
(commencing with the Commencement Date until the date of the delivery of the new
letter of credit) that no Event of Default has occurred under this Lease. Tenant
covenants and agrees that no less than sixty (60) days prior to the third (3rd)
anniversary of the execution date hereof, Tenant shall deliver a cash security
deposit in an amount equal to Fifty Thousand Eight Hundred Thirty-Five Dollars
($50,835.00) as a Security Deposit for the full and timely payment and
performance by Tenant of its obligations under this Lease. Landlord may apply
any or all of the Security Deposit towards the payment of Any sum or the
performance of any obligation which Tenant was obligated, but failed, to pay or
perform hereunder. The Security Deposit shall not be considered an advance
payment of Rent by Tenant or a measure of or a limit to Landlord's damages upon
an Event of Default.

                                                                      Page 23
<PAGE>

       28.3   RULES AND REGULATIONS.  Tenant shall comply with the Building
Rules and Regulations attached hereto, as the same may be amended or promulgated
by Landlord from time to time. However, the Rules and Regulations may not be
amended or modified in any way which would impose additional material economic
obligations upon Tenant. The terms of this Lease shall control over any conflict
with rules and regulations.

       28.4   CONSENTS.  Unless otherwise provided herein, all consents or
approvals required or permitted of Landlord hereunder shall not be unreasonably
withheld.

       TENANT ACKNOWLEDGES THAT, EXCEPT AS OTHERWISE SPECIFICALLY SET FORTH
HEREIN, LANDLORD HAS MADE NO WARRANTIES TO TENANT AS TO THE CONDITION OF THE
PREMISES, EITHER EXPRESS OR IMPLIED, AND LANDLORD ANDTENANT EXPRESSLY DISCLAIM
ANY IMPLIED WARRANTY THAT THE PREMISES ARE SUITABLE FOR TENANT'S INTENDED
COMMERCIAL PURPOSE.

       EXECUTED as of the date and year above first written.

                     TENANT:       OBJECTSPACE, INC.,
                                   a Texas corporation

                                   By:  /s/ JOHN W. PRITCHETT
                                       -------------------------------------
                                        Name:  John W. Pritchett
                                              ------------------------------
                                        Title: Chief Financial Officer
                                              ------------------------------

                     LANDLORD:     CARRAMERICA REALTY, L.P., a Delaware limited
                                   partnership

                                   By:  CarrAmerica, Realty GP Holdings, Inc.,
                                        a Delaware corporation, its General
                                        Partner

                                   By:  /s/  ROBERT E. PETERSON
                                       -------------------------------------
                                        Name:  Robert E. Peterson
                                              ------------------------------
                                        Title: Regional Managing Director
                                              ------------------------------

                                                                      Page 24
<PAGE>

                                    EXHIBIT INDEX

Exhibit A:           Glossary

Exhibit B:           Floor Plan

Exhibit C:           Rules and Regulations

Exhibit D:           Work Letter

Exhibit E:           Property Legal Description

Exhibit F:           First Right of Refusal Space

Exhibit G:           Renewal Options

Exhibit H:           Air Conditioning and Heating Specifications

                                                                      Page 25
<PAGE>

                                     EXHIBIT A

GLOSSARY OF DEFINED TERMS

       1      "ADDENDUM" shall mean the Addendum, if any, attached to this
Lease.

       2.     "AFFILIATE" shall mean a person or party who or which controls, is
controlled by or is under common control with another person or party.

       3.     "BUILDING" shall mean that certain nine (9) floor office building
and garage structure constructed on the Land, the street address of which is
14901 Quorum Drive, Dallas, Texas, and is more particularly described in the
deed recorded in Volume 95223, Page 1085 of the Deed Records of Dallas County,
Texas. The term "Building" shall include all fixtures and appurtenances in and
to the aforesaid structure, including specifically but without limitation all
above grade walkways and all electrical, mechanical, plumbing, security,
elevator, boiler, HVAC, telephone, water, gas, storm sewer, sanitary sewer and
all other utility systems and connections, all life support systems, sprinklers,
smoke detection and other fire protection systems, and all equipment, machinery,
shafts, flues, piping, wiring, ducts, duct work, panels, instrumentation and
other appurtenances relating thereto.

       4.     "BUILDING OPERATING HOURS" shall mean 7:00 a.m. to 6:30 p.m.
Monday through Friday and Saturday 8:00 a.m. to 1:00 p.m., exclusive of Sundays
and Holidays.

       5.     "BUILDING RULES AND REGULATIONS" shall mean the rules and
regulations governing the Complex promulgated by Landlord from time to time. The
current Building Rules and Regulations maintained by Landlord are attached as
EXHIBIT C hereto.

       6.     "BUILDING STANDARD" when applied to air item, shall mean such item
as has been designated by Landlord (orally or in writing) as generally
applicable throughout the leased portions of the Building.

       7      "COMMENCEMENT DATE" shall mean the date of the commencement of the
Term, as determined pursuant to Section 6.3, with respect to the Premises.
However, in the event the Commencement Date for the portion of the Premises
other than the Ground Floor Premises differs from the Commencement Date for the
Ground Floor Premises, the earlier of such dates shall be determinative of the
Term.

       8.     "COMMON AREAS" shall mean all areas and facilities within the
Complex which have been constructed and are being maintained by Landlord for the
common, general, non-exclusive use of all tenants in the Building, and shall
include restrooms, lobbies, corridors, service areas, elevators, stairs and
stairwells, the Parking Facility, driveways, loading areas, ramps, walkways and
landscaped areas.

       9.     "COMPLEX" shall mean the Land and all improvements thereon,
including the Building and the Parking Facility.

       10.    "EXPENSE STOP" shall mean that portion of the Operating Expenses,
expressed in terms of dollars per square foot of Net Rentable Area per Fiscal
Year, which will be deducted from the computation of Additional Rent. Unless
changed by mutual agreement of the parties, the "Expense Stop" shall be equal to
the actual operating expenses per rentable square foot for the 1997 calendar
year.

                                     A-1
<PAGE>

       11.    "FISCAL YEAR" shall mean the fiscal year (or portion thereof) of
Landlord as elapses during the Term. The Fiscal Year currently commences on
January 1; however, Landlord may change the Fiscal Year at any time or times.

       12.    "FORCE MAJEURE" shall mean the occurrence of any event which
hinders, prevents or delays the performance by Landlord of any of its
obligations hereunder and which is beyond the reasonable control of Landlord.

       13.    "HOLIDAYS" shall mean (a) New Year's Day, Memorial Day,
Independence Day, Labor Day, Thanksgiving Day and Christmas Day, (b) other days
on which national or state banks located in the state where the Complex is
located must or may close for ordinary operations and (c) other days which are
commonly observed as holidays by the majority of tenants of the Building. If the
Holiday occurs on a Saturday or Sunday, the Friday preceding or the Monday
following may, at Landlord's discretion, be observed as a Holiday.

       14.    "HVA" shall mean the heating, ventilation and air conditioning
systems in the Building.

       15.    "IMPOSITIONS" shall mean (a) all real estate, personal property,
rental, water, sewer, transit, use, occupancy and other taxes, assessments,
charges, excises and levies (including any interest, costs or penalties with
respect thereto), general and special, ordinary and extraordinary, foreseen and
unforeseen of any kind and nature whatsoever which are assessed, levied, charged
or imposed upon or with respect to the Complex, or any portion thereof, or the
sidewalks, streets or alley ways adjacent thereto, or the ownership, use,
occupancy or enjoyment thereof, and (b) all charges for any easement, license,
permit or agreement maintained for the benefit of the Complex. "Impositions"
shall not include income taxes, estate and inheritance taxes, excess profit
taxes, franchise taxes, taxes imposed on or measured by the income of Landlord
from the operation of the Complex, and taxes imposed on account of the transfer
of ownership of the Complex or the Land. If any or all of the Impositions be
discontinued and, in substitution therefor, taxes, assessments, charges, excises
or impositions be assessed, levied, charged or imposed wholly or partially on
the Rents received or payable hereunder (a "SUBSTITUTE IMPOSITION"), then the
Substitute Imposition shall be deemed to be included within the term
"IMPOSITIONS".

       16.    "LAND" shall mean the real property on which the Building is
constructed and which is further described in EXHIBIT E hereto.

       17.    "LANDLORD'S MORTGAGEE" shall mean the mortgagee of any mortgage,
the beneficiary of any deed of trust, the pledgee of any pledge, the secured
party of any security interest, the assignee of any assignment and the
transferee of any other instrument of transfer (including the ground lessor of
any ground lease on the Land) now or hereafter in existence on all or any
portion of the Complex, and their successors, assigns and purchasers.
"MORTGAGE" shall mean any such mortgage, deed of trust, pledge, security
agreement, assignment or transfer instrument, including all renewals, extensions
and rearrangements thereof and of all debts secured thereby.

       18.    "LANDLORD'S WORK" shall mean all improvements, components,
assemblies, installations, finish, labor, materials and services that Landlord
is required to furnish, install, perform, provide or apply to the Premises as
specified in the Work Letter.

       19.    "PREMISES" shall mean the area leased by Tenant pursuant to this
Lease as outlined on the floor plan drawing attached as EXHIBIT B hereto and all
other space added to the Premises pursuant to the terms of this Lease. The
Premises includes the space between the top surface of the floor slab of the

                                     A-2
<PAGE>

outlined area and the finished surface of the ceiling immediately above. "GROUND
FLOOR PREMISES" shall mean the portion of the Premises comprising 8,606 square
feet located on the ground floor of the Building.

       20.    "LEGAL REQUIREMENTS" shall mean any and all (a) judicial
decisions, orders, injunctions, writs, statutes, rulings, rules, regulations,
promulgations, directives, permits, certificates or ordinances of any
governmental authority in any way applicable to Tenant or the Complex, including
but not limited to the Building Rules and Regulations, zoning, environmental and
utility conservation matters, (b) requirements imposed on Landlord by any
Landlord's Mortgagee, (c) insurance requirements and (d) other documents,
instruments or agreements (written or oral) relating to the Complex or to which
the Complex may be bound or encumbered.

       21.    "NET RENTABLE AREA" whether of the Premises or the Complex shall
mean the area determined pursuant to the American National Standard Method for
measuring floor space in office buildings, as set forth in American National
Standard's Institute publication Z65.1-1980 and as, from time to time, revised.
Landlord and Tenant hereby stipulate that, unless and until revised by virtue of
the application of the standards set forth in said publication or in a revised
publication, the Net Rentable Area of the Premises shall be 28,606 square feet
and the Net Rentable Area of the Building shall be 174,159 square feet.

       22.    "OPERATING EXPENSE" shall mean all costs and expenses which
Landlord pays or accrues by virtue of the ownership, use, management, leasing,
maintenance, service, operation, insurance or condition of the Complex during a
particular Fiscal Year or portion thereof as determined by Landlord or its
certified public accountants in accordance with generally accepted accounting
principles PLUS (in instances where the Building was not fully occupied for the
entire period in question) all additional costs and expenses which Landlord or
such accountant reasonably determines Landlord would have paid or accrued during
such period if the Building has been fully occupied (defined as ninety-five
percent (95%) occupied]. "OPERATING EXPENSES" shall include, but shall not be
limited to, the following to the extent they relate to the Complex:

              (a)    all Impositions and other governmental charges;

              (b)    all insurance premiums charged for policies obtained by
       Landlord, which may include without limitation, at Landlord's election,
       (i) fire and extended coverage insurance including earthquake, windstorm,
       hail, explosion, riot, strike, civil commotion, aircraft, vehicle and
       smoke insurance, (ii) public in liability and property damage insurance,
       (iii) elevator insurance, (iv) workmen's compensation insurance for the
       employees covered by clause (h), (v) boiler, machinery, sprinkler, water
       damage, legal liability, burglary, hold-up, fidelity and pilferage
       insurance, (vi) rental loss insurance and (vii) such other insurance as
       Landlord may elect to obtain;

              (c)    all customary and reasonable deductible amounts incurred in
       any Fiscal Year relating to an insurable loss;

              (d)    all maintenance, repair, replacement and painting costs;

              (e)    all janitorial, custodial, cleaning, washing-, landscaping,
       landscape maintenance, trash removal and pest control costs;

              (f)    all security costs;

                                     A-3
<PAGE>

management of the Complex by Landlord or an Affiliate of Landlord, reasonably
allocated based on time actually spent on the Project as opposed to other
projects;

              (i)    all costs of leasing or purchasing supplies, tools,
       equipment and materials;

              (j)    all management fees and other charges for management
       services (including, without limitation, travel and related expenses),
       whether provided by an independent management company, by Landlord or by
       an Affiliate of Landlord;

              (k)    all fees and other charges paid under all maintenance and
       service agreements, including but not limited to window cleaning,
       elevator and HVAC maintenance;

              (1)    all legal, accounting and auditing fees and expenses; and

              (m)    amortization of the cost of acquiring, financing and
       installing capital items which are intended to reduce (or avoid increases
       in) operating expenses, but only to the extent of the reduction or
       avoidance, or which are required by a governmental authority. Such costs
       shall be amortized over the reasonable life of the items in accordance
       with generally accepted accounting principles, but not beyond the
       reasonable life of the Building.

"OPERATING EXPENSES" shall not include (i) expenditures classified as capital
expenditures for federal income tax purposes except as set forth in clause (m),
(ii) costs for which Landlord is entitled to specific reimbursement by Tenant,
by any other tenant of the Building or by any other third party, (iii)
allowances specified in the Work Letter for expenses incurred by Landlord for
improvements to the Premises, (iv) leasing commissions, and all non-cash
expenses (including depreciation), except for the amortized costs specified in
clause (in), (v) land or ground rent if applicable, (vi) debt service on any
indebtedness secured by the Complex (except debt service on indebtedness to
purchase or pay for items specified as permissible "OPERATING EXPENSES" under
clause (a) through (m)], (vii) costs of repairs, restoration, replacements or
other work occasioned by the exercise by a governmental authority of the right
of eminent domain to the extent to which the actual cost for such repairs,
restoration, replacements or other occasioned thereby is compensated by such
authority; (viii) attorneys' fees, costs, disbursements and other expenses
incurred in connection with negotiations or disputes with tenants, prospective
tenants, management agents, purchasers or mortgagees of the Building; (ix)
allowances, concessions and other costs and expenses incurred in completing,
renovating or otherwise improving, decorating or redecorating space for tenants,
or prospective tenants, or vacant, leasable space in the Complex; (x) any cost
that should be capitalized in accordance with generally accepted accounting
principles except capital improvements as set forth in clause (m); (xi) costs
incurred in connection with the sale, financing, refinancing, mortgaging,
selling or change of ownership of the Building; (xii) costs or expenses of
utilities directly metered to tenants of the Building and payable separately by
such tenants and costs of additional electrical equipment installed in premises
of other tenants of the Building and costs of electricity consumed through such
additional electrical equipment, whether or not such costs are payable by such
other tenants, and the costs of heating, ventilating and air-conditioning
services provided to other tenants of the Building during hours other than
Building standard hours, whether or not such costs are payable by such other
tenants; (xiii) costs of repairs, restoration, replacements or other work
occasioned by the gross negligence or intentional tort of Landlord, or any
representative, employee, agent or affiliate of Landlord; (xiv) costs of
repairing, replacing or otherwise correcting warrantied defects in construction
of Tenant Improvements and leasehold improvements of other tenants of the
Building; (xv) costs or expenses relating to another tenant's space which were
incurred in rendering any service or benefit to such tenant that Landlord was
not required, or were for a service in excess of the service that Landlord

                                     A-4
<PAGE>

was required, to provide Tenant hereunder; (xvi) costs of Landlord's general
corporate overhead and general administrative expenses, organizational fees,
and partnership expenses, and the cost of personnel not actively involved in
management or marketing of the Complex; (xvii) costs associated with
operating health, exercise, luncheon, conference/communications club or
facilities; (xviii) management fees in excess of the lesser of five percent
(5%) of gross revenues of the Building or market management fees; (xix) costs
of restoration or repair paid by insurance, condemnation, third parties or
tenants (excluding deductible amounts so paid); (xx) costs which would be
included in Operating Expenses which are paid to any affiliate of Landlord to
the extent such costs exceed competitive market rates for such services; and
(xxi) costs incurred to correct violations within the Complex of any law,
rule, order or regulation which was in effect as of the date hereof. All
supply and service contracts will be competitively bid by independent third
parties each year. Operating Expenses will be calculated in years subsequent
to 1997 in a manner materially consistent with the calculations made in 1997.
Notwithstanding anything contained herein to the contrary, in no evnt shall
Controllable Expenses (hereinafter defined) that constitute a portion of the
Operating Expenses be increased from year to year by more than eight percent
(8%) per annum. As used herein, "CONTROLLABLE EXPENSES" shall mean those
expenses determined by and within the exclusive control of Landlord and shall
include all Operating Expenses enumerated in Paragraph 22 except those set
forth in Paragraph 22(a), (b), (g) and (m).

       23.    "PARKING FACILITY" shall mean (a) any parking. garage and any
other parking lot or facility adjacent to or in the Complex servicing the
Building and (b) any parking area, open or covered, leased by Landlord to
service the Building.

       24.    "RENT" shall mean Base Rent and Additional Rent and all other
amounts provided for under this Lease to be paid by Tenant, whether as
additional rent or otherwise. "BASE RENT" shall mean the base rent specified in
Section 5.1. "ADDITIONAL RENT' shall mean the additional rent specified in
Section 5.2.

       25.    "SECURITY DEPOSIT" shall mean Fifty Thousand Eight Hundred
Thirty-Five Dollars ($50,835) to be paid by Tenant sixty (60) days prior to die
expiration of the Letter of Credit as security for the full and faithful
performance of the obligations of Tenant under this Lease.

       26.    "TAKING" or "TAKEN" shall mean the actual or constructive
condemnation, or the actual or constructive acquisition by or under threat of
condemnation, eminent domain or similar proceeding, by or at the direction of
any governmental authority or agency.

       27.    "TENANT'S SHARE" shall mean the proportion by which the Net
Rentable Area of the Premises bears to the Net Rentable Area of the Building.
"TENANT'S SHARE" shall be adjusted by Landlord from time to time to reflect
adjustments to the then current Net Rentable Area of the Building or the
Premises. "TENANT'S SHARE" shall initially mean sixteen and four hundred
twenty-five thousandths percent (16.425%).

       28.    "TRANSFER" shall mean (a) an assignment (direct or indirect,
absolute or conditional, by operation of law or otherwise) by Tenant of all or
any portion of Tenant's interest in this Lease or the leasehold estate created
hereby, (b) a sublease of all or any portion of the Premises or (c) the grant or
conveyance by Tenant of any concession or license within the Premises. If Tenant
is a corporation then any transfer of this Lease by merger, consolidation or
dissolution, or by any change in the power to vote a majority of the voting
stock (being the shares of stock regularly entitled to vote for the election of
directors) in Tenant outstanding at the time of execution of this Lease shall
constitute a Transfer. Notwithstanding anything contained in Section 10 of this
Lease or this definition of "Transfer" to the contrary, Tenant shall have the
right, upon ten (10) days prior written

                                     A-5
<PAGE>

notice to Landlord, to consummate a Transfer to an Affiliate. As used herein,
the term "Affiliate" means any person or entity that directly or indirectly
Controls, is Controlled by, or is under common Control with, the entity in
question; and the term "Control" means possession, directly or indirectly, of
the power to direct or cause the direction of the management and policies of
an entity whether through ownership of voting securities, by contract or
otherwise, and also shall include any entity that acquires all or
substantially all of the assets or stock or other ownership interests in or
of Tenant. "TRANSFEREE" shall mean the assignee, sublessee, pledgee,
concessionee, licensee or other transferee of all or any portion of Tenant's
interest in this Lease, the leasehold estate created hereby or the Premises.

       29.    "WORK LETTER" shall mean the agreement, if any, attached as
EXHIBIT D hereto between Landlord and Tenant for the construction of
improvements in the Premises.

                                     A-6
<PAGE>

                                      EXHIBIT B

                                      FLOOR PLAN

                                     B-1
<PAGE>

                                     [FLOOR PLAN]

                                     EXHIBIT C

                                RULES AND REGULATIONS

       1.     Landlord may from time to time adopt appropriate systems and
procedures for the security or safety of the Building, any persons occupying,
using, or entering the Building, or any equipment, finishings, or contents of
the Building, and each tenant shall comply with such systems and procedures.

       2.     Tenant's employees, visitors, and licensees shall not loiter in or
interfere with the use of the Parking Facility or the Complex's driveway or
parking areas nor consume alcohol in the common areas of the Complex or the
Parking Facility. The sidewalks, halls, passages, exits, entrances, elevators,
escalators, and stairways of the Building will not be obstructed by any tenants
or used by any of them for any purpose other than for ingress to and egress from
their respective premises. The halls, passages, exits, entrances, elevators,
escalators, and stairways are not for the general public, and Landlord may
control and prevent access to them by all persons whose presence, in the
reasonable judgment of Landlord, would be prejudicial to the safety, character,
reputation and interests of the Building and its tenants; in determining whether
access will be denied, Landlord may consider attire worn by a person and its
appropriateness for an office building, whether shoes are being worn, use of
profanity, either verbally or on clothing, actions of a person (including,
without limitation, spitting, verbal abusiveness, and the like), and such other
matters as Landlord may reasonably consider appropriate.

       3.     No sign, placard, picture, name, advertisement, or notice visible
from the exterior of any tenant's premises shall be inscribed, painted, affixed,
or otherwise displayed by any tenant on any part of the Building without the
prior written consent of Landlord. All approved signs or lettering on doors will
be printed, painted, affixed, or inscribed at the expense of the tenant desiring
such by a person approved by Landlord. Material visible from outside the
Building will not be permitted. Landlord may remove such material without any
liability, and may charge the expense incurred by such removal to the tenant in
question.

       4.     No curtains, draperies, blinds, shutters, shades, screens, or
other coverings, hangings, or decorations will be attached to, hung, or placed
in, or used in connection with any window of the Building or the Premises.

       5.     The sashes, sash doors, skylights, windows, heating, ventilating,
and air conditioning vents and doors that reflect or admit light and air into
the halls, passageways, or other public places in the Building shall not be
covered or obstructed by any tenant, nor will any bottles, parcels, or other
articles be placed on any window sills.

       6.     No showcases or other articles will be put in front of or affixed
to any part of the exterior of the Building, nor placed in the public halls,
corridors, or vestibules without the prior written consent of Landlord.

       7.     No tenant will permit its Premises to be used for lodging or
sleeping. No cooking will be done or permitted by any tenant on its premises,
except in areas of the premises which are specially constructed for cooking, so
long as such use is in accordance with all applicable federal, state, and city
laws, codes, ordinances, rules, and regulations.

                                     C-1
<PAGE>

       8.     No tenant will employ any person or persons other than the
cleaning service of Landlord for the purpose of cleaning the premises, unless
otherwise agreed by Landlord in writing. If any tenant's actions result in any
increased expense for any required cleaning, Landlord may assess such tenant for
such expenses. Janitorial service will not be furnished on nights to offices
which are occupied after business hours on those nights unless, by prior written
agreement of Landlord, service is extended to a later hour for specifically
designated offices.

       9.     The toilets, urinals, wash bowls, and other plumbing fixtures will
not be used for any purposes other than those for which they were constructed,
and no sweepings, rubbish, rags, or other foreign substances will be thrown in
them. All damages resulting from any misuse of the fixtures will be borne by the
tenant who, or whose servants, employees, agents, visitors, or licensees, have
caused the damage.

       10.    No tenant will deface any part of the premises or the Building.
Without the prior written consent of Landlord, no tenant will lay linoleum, or
other similar floor covering, so that it comes in direct contact with the floor
of such tenant's premises. If linoleum or other similar floor covering is to be
used, an interlining of builder's deadening felt will be first affixed to the
floor, by a paste or other material, soluble in water. The use of cement or
other similar adhesive material is expressly prohibited.

       11.    No tenant will alter, change, replace, or rekey any lock or
install a new lock or a knocker on any door of the premises. Landlord, its agent
or employee, will retain a master key to all door locks on the premises. Any new
door locks required by a tenant or any change in keying of existing locks will
be installed or changed by Landlord following such tenant's written request to
Landlord and will be at such tenant's expense. All new locks and rekeyed locks
will remain operable by Landlord's master key. Landlord will furnish to each
tenant, free of charge, ten (10) keys to each door lock on its premises.
Landlord will have the right to collect a reasonable charge for additional keys
and access cards requested by any tenant. Each tenant, upon termination of its
tenancy, will deliver to Landlord all keys and access cards for the premises and
Building which have been furnished to such tenant.

       12.    The elevator designated for freight by Landlord will be available
for use by all tenants in the Building during the hours and pursuant to such
procedures as Landlord may determine from time to time. The persons employed to
move tenant's equipment, material, furniture, or other property in or out of the
Building must be acceptable to Landlord; such persons must be a locally
recognized professional mover, whose primary business is the performing of
relocation services, and must be bonded and fully insured. A certificate or
other verification of such insurance must be received and approved by Landlord
prior to the start of any moving operations. Insurance must be sufficient, in
Landlord's sole opinion, to cover all personal liability, theft, or damage to
the Building, including without limitation floor coverings, doors, walls,
elevators, stairs, foliage, and landscaping. All moving operations will be
conducted at such times and in such a manner as Landlord may direct, and all
moving will take place during nonbusiness hours unless Landlord otherwise agrees
in writing. The moving tenant shall be responsible for the provision of Building
security during all moving operations, and shall be liable for all losses and
damages sustained by any party as a result of the failure to supply adequate
security. Landlord may prescribe the weight, size, and position of all
equipment, materials, furniture, or other property brought into the Buildings.
Heavy objects will, if considered necessary by Landlord, stand on wood strips of
such thickness as is necessary to distribute the weight properly. Landlord will
not be responsible for loss of or damage to any such property from any cause,
and all damage done to the Building by moving or maintaining such property will
be repaired at the expense of the moving tenant. Landlord may inspect all such
property to be brought into the Building and to exclude from the Building all
such property which violates any of these rules and regulations or the lease of
which these rules and regulations area part.

                                     C-2
<PAGE>

Supplies, goods, materials, packages, furniture, and all other items of every
kind delivered to or taken from the premises will be delivered or removed
through the entrance and route designated by Landlord.

       13.    No tenant will use or keep in the premises or the Building any
kerosene, gasoline, or inflammable or combustible or explosive fluid or material
or chemical substance other than limited quantities of them reasonably necessary
for the operation or maintenance of office equipment or limited quantities of
cleaning fluids and solvents required in normal operation of the premises.
Without Landlord's prior written approval, no tenant will use any method of
heating or air conditioning other than that supplied by Landlord. No tenant will
keep any firearms within the Premises. No tenant will use or keep or permit to
be used or kept any foul or noxious gas or substance in the premises, or permit
of suffer the premises to be occupied or used in an manner offensive or
objectionable to Landlord or other occupants of the Building by reason of noise,
odors, or vibrations, or interfere in any way with other tenants or those having
business in the Building.

       14.    Landlord may without notice and without liability to any tenant,
change the name and street address of the Building.

       15.    Landlord will have the right to prohibit any advertising by
tenant, mentioning the Building, which, in Landlord's reasonable opinion, tends
to impair the reputation of the Building or its desirability as a Building for
offices, and upon written notice from Landlord, tenant will discontinue such
advertising.

       16.    Tenant will not bring any animals or birds into the Building, and
will not permit bicycles or other vehicles inside or on the sidewalks outside
the Building except in areas designated from time to time by Landlord for such
purposes.

       17.    All persons entering or leaving the Building at any time other
than the Building's business hours shall comply with such off-hour regulations
as Landlord may establish and modify from time to time. Landlord may limit or
restrict access to the Building during such periods.

       18.    Each tenant will store all its trash and garbage within its
premise. No material will be placed in the trash boxes or receptacles if such
material is of such nature that it may not be disposed of in the ordinary and
customary manner of removing and disposing of trash and garbage without being in
violation of any law or ordinance governing such disposal. All garbage and
refuse disposal will be made only through entryways and elevators provided for
such purposes and at such times as Landlord may designate. No furniture,
appliances, equipment, or flammable products of any type may be disposed of in
the Building trash receptacles.

       19.    Canvassing, peddling, soliciting, and distribution of handbills or
any other written materials in the Building are prohibited, and each tenant will
cooperate to prevent same.

       20.    Each tenant shall keep the doors of the premises closed and locked
and shall shut off all water faucets, water apparatus, and utilities before
tenant or tenant's employees leave the premises, so as to prevent waste or
damage, and for any default or carelessness in this regard tenant shall be
liable for all injuries sustained by other tenants or occupants of the Building
or Landlord. On multiple-tenancy floors, all tenants will keep the doors to the
Building corridors closed at all times except for ingress and egress.

                                     C-3
<PAGE>

                                      EXHIBIT D

                                WORK LETTER AGREEMENT

       This Work Letter Agreement supplements and is hereby incorporated in that
certain Lease Agreement (hereinafter referred to as the "Lease") dated and
executed concurrently herewith by and between CarrAmerica Realty, L.P., a
Delaware limited partnership (hereinafter referred to as "Landlord"), and
ObjectSpace, Inc., a Texas corporation (hereinafter referred to as "Tenant")
with the terms defined in the Lease to have the same definition where used
herein.

              (i)    The Premises are leased to Tenant in their "AS IS"
       condition and this Work Letter Agreement is intended to set forth the
       obligations of Landlord and Tenant with respect to the preparation of the
       Premises for Tenant's occupancy. All improvements described in this Work
       Letter Agreement to be constructed in and upon the Premises are
       hereinafter referred to as the "Tenant Improvements."  It is agreed that
       construction of the Tenant Improvements will be completed in accordance
       with the procedures set forth in this Work Letter Agreement.

              (ii)   Tenant shall devote such time in consultation with Landlord
       or Landlord's agent as may be required to provide all necessary
       information to Landlord or Landlord's agent as Landlord deems necessary
       in order to enable Landlord to complete, and obtain Tenant's written
       approval of, the final layout, drawings, and plans for the Premises. If
       Tenant fails to furnish any such information, or fails to agree on tenant
       finish out contractors, or fails to approve layout, drawings, or plans
       within ten (10) Business Days after written request, Landlord may, at its
       election, be discharged of its obligations under this Work Letter
       Agreement, but the same shall not affect or diminish Tenant's duties and
       obligations set forth in the Lease, and Tenant agrees to pay on demand
       all costs and expenses and increased unit prices incurred by Landlord on
       account of Tenant's failure to furnish such information and approved
       drawings within such prescribed time limits. All of Tenant's plans and
       specifications shall be subject to Landlord's consent, the granting or
       denial of which shall be in Landlord's reasonable discretion.

              (iii)  Space planning and construction drawings shall be prepared
       by Tenant's architect. Landlord shall bear the cost of the space planning
       and construction drawings which shall be prepared by Tenant's architect;
       provided, however, such costs and expenses, including phones and cabling
       reflected on such drawing, shall be paid out of the Leasehold
       Improvements allowance defined in (viii) hereof and in no event shall
       Landlord's obligation for the cost of such space planning and
       construction drawings, phones and cabling exceed an amount equal to $2.00
       per square foot of Net Rentable Area in the Premises (which for purposes
       hereof is agreed to be 28,606 square feet), being the total sum of
       $57,212.00. Tenant shall pay for any and all additional space planning
       costs beyond Landlord's obligation specified above. Tenant shall
       furthermore be responsible for the design, function and maintenance of
       all special improvements, whether installed by Landlord at Tenant's
       request or installed by Tenant with Landlord's prior written approval.
       Tenant shall use the Building Standard materials as defined in EXHIBIT
       D-1 unless other materials are expressly approved in writing by Landlord.

              (iv)   Prior to commencing any construction of Tenant
       Improvements, Landlord and Tenant shall agree upon three (3) mutually
       acceptable qualified tenant finish contractors who shall provide
       competitive bids for the Tenant Improvements. After receipt of such three
       (3) competitive bids, Landlord and Tenant shall select the successful
       bidder to construct the Tenant Improvements and Landlord shall enter into
       a contract with the successful bidder to construct the Tenant
       Improvements. In the event that any performance or payment bonds are

                                     D-1
<PAGE>

       required by Landlord, Landlord shall be responsible for the payment of
       such expenses and such expenses shall not be apart of the Leasehold
       Improvements Allowance. Any building stock materials used by Tenant
       that are required out of Landlord's building stock shall be charged
       against the Leasehold Improvements Allowance at cost. Tenant is not
       required to use such building stock materials. Landlord shall provide
       all utilities, toilets, security and elevator service to the Premises
       and shall provide the general contractor with parking at no cost to
       Tenant or its contractors or subcontractors. Landlord shall not charge
       a construction management services fee to Tenant.

              (v)    In the event the actual cost of construction shall exceed
       the Leasehold Improvements Allowance (such amounts exceeding the
       Leasehold Improvements Allowance being herein referred to as the "Excess
       Costs"), Tenant shall pay to Landlord such Excess Costs as follows:

                     (a)    Tenant shall deliver to Landlord prior to
              commencement of construction an amount equal to fifty percent
              (50%) of the Excess Costs as then estimated by Landlord.

                     (b)    After substantial completion of the Tenant
              Improvements, but prior to occupancy of the Premises by Tenant,
              Tenant shall pay to Landlord on demand an amount which when added
              to the initial payment described in subparagraph (a) above equals
              ninety percent (90%) of the Excess Costs as then estimated by
              Landlord.

                     (c)    As soon as the final accounting can be prepared and
              submitted to Tenant, Tenant shall pay on demand to Landlord the
              entire balance of the Excess Costs based upon the actual cost of
              construction.

              The statements of costs submitted to Landlord by Landlord's
              contractors shall be conclusive for purposes of determining the
              actual cost of the items described therein. The amounts payable
              hereunder constitute additional rent payable pursuant to the
              Lease, and the failure to timely pay same constitutes an Event of
              Default under the Lease.

              Notwithstanding the foregoing, in the event the actual cost of
              removal of the bank vault located within the Ground Floor Premises
              exceeds the cost submitted to Landlord by Landlord's contractors,
              such budgetary shortfall shall not be assessed against the
              Leasehold Improvements Allowance or otherwise charged to Tenant.
              Tenant waives and hereby disclaims any interest in the remedies
              secured by Landlord from Landlord's contractors to secure
              performance of the construction specifications, including, without
              limitation, any bond or letter of credit delivered by Landlord's
              contractors to Landlord to secure removal of such bank vault at a
              cost of an amount not to exceed the contract quote therefor.

                     (vi)   If Tenant shall request any change, addition or
              alteration in the working drawings, after approval by Landlord and
              Tenant, Landlord shall have such working drawings prepared, and
              Tenant shall promptly reimburse Landlord for the cost thereof.
              Promptly upon completion of the revisions, Landlord shall notify
              Tenant in writing of the cost which will be chargeable to Tenant
              by reason of such change, addition or deletion. Tenant shall,
              within three (3) Business Days, notify Landlord in writing whether
              it desires to proceed with such change, addition or deletion. In
              the absence of such written authorization, Landlord shall have the

                                     D-2
<PAGE>

              option to continue work on the Premises disregarding the requested
              change, addition or alteration. In the event such revisions
              result in a higher estimate of the cost of construction, Tenant
              shall pay to Landlord an amount sufficient to provide Landlord
              with the above described fifty percent (50%) [of if applicable,
              ninety percent (90%)] payment toward Excess Costs.

                     (vii)  Following approval of the plans and the payment by
              Tenant of the required portion of the Excess Costs, if any,
              Landlord shall cause the Tenant Improvements to be constructed in
              accordance with the approved plans. Unless otherwise specifically
              provided in the approved plans, all material used in the
              construction of the Tenant's Improvements shall be of such quality
              as determined by Landlord and approved by Tenant. Landlord shall
              notify Tenant of substantial completion of the Tenant
              Improvements.

                     (viii) Landlord agrees to construct the Tenant Improvements
              in accordance with the approved plans at its cost and expense;
              provided, however, in the event the actual cost of construction of
              the Tenant Improvements exceeds Twelve and 62/100 Dollars ($12.62)
              per square foot of Net Rentable Area in the Premises (which for
              purposes hereof is agreed to be 28,606 square feet), being the
              total sum of $361,066.00, such amount being referred to as the
              "Leasehold Improvements Allowance"), Tenant shall pay the Excess
              Costs as prescribed in EXHIBIT D. In the event the actual cost of
              the Tenant Improvements is less than the Allowance, Tenant shall
              not be entitled to any credit for any amounts not applied to the
              cost of the Tenant Improvements.

                     (ix)   Notwithstanding anything herein to the contrary,
              Landlord shall provide an additional Two Dollars ($2.00) per
              rentable square foot to Tenant for the payment of Excess Costs,
              which amount shall be amortized at an annual interest rate of
              twelve percent (12%) over the first (?) twenty-four (24) months of
              the Lease term commencing with the Commencement Date. In the event
              Tenant elects to utilize such additional Two Dollars ($2.00) per
              rentable square foot, the Letter of Credit shall be increased by
              an amount equal to the cost per rentable square foot utilized by
              Tenant and Tenant shall provide Landlord with a substituted letter
              of credit reflecting such increased amount.

                                     D-3
<PAGE>

              It is hereby acknowledged by both Tenant and Landlord that this
       EXHIBIT D has been executed as of, and shall become part of the Lease
       dated April 29, 1997.

                       TENANT        OBJECTSPACE, INC.
                                     a Texas corporation

                                     By: /s/ JOHN W. PRITCHETT
                                        -----------------------------------
                                     Name:   John W. Pritchett
                                          ---------------------------------
                                     Title:  CFO
                                           --------------------------------
                                     Date:   April 29, 1997
                                           --------------------------------

                       LANDLORD      CARRAMERICA REALTY, L.P., a
                                     Delaware limited partnership

                                     By:  CarrAmerica Realty GP Holdings,
                                          Inc., a Delaware corporation its
                                          General Partner

                                     By: /s/ ROBERT E. PETERSON
                                        -----------------------------------
                                     Name:   Robert E. Peterson
                                          ---------------------------------
                                     Title:  Regional Managing Director
                                           --------------------------------

                                     D-4
<PAGE>

                                    EXHIBIT D-1

1.     The Building Standard (herein so called) materials are the following:

A.     FLOORING:     Grade and quality of carpeting to be selected by Landlord,
                     with color to be selected by Tenant from those offered by
                     Landlord.

B.     WINDOW
       COVERING:     At Landlord's option, mini blinds or drapes in Landlord's
                     uniform color.

C.     CEILING:      Acoustical tiles - Grid system.

D.     PARTITIONS:   Sheetrock partitions with tape, bed, texture and paint
                     finish, and/or vinyl pre-clad sheetrock.

E.     DOORS:        Hollow core door with metal frame and hardware.

F.     ELECTRICAL
       POWER
       OUTLETS:      Standard 110 volt duplex wall-mounted convenience outlets.

G.     LIGHT
       SWITCHES:     Single pole light switches.

H.     TELEPHONE
       FACILITIES:   Standard unwired telephone outlets (ring and string)
                     mounted on partitions. Tenant must make timely arrangements
                     for telephone installation and is responsible for all
                     charges related to such installation.

I      LIGHT
       FIXTURES:     Recessed fluorescent lighting fixtures.

                                     D-5
<PAGE>

                                     EXHIBIT E

                              PROPERTY LEGAL DESCRIPTION

BEING a tract of land situated in the City of Addison, Dallas County, Texas, out
of the Josiah Pancoast Survey, Abstract 1146; and being part of Block 2 of
Quorum, an Addition to the City of Addison as recorded in Volume 79100, Page
1895 of the Deed Records of Dallas County, Texas; and being more particularly
described as follows:

COMMENCING at a point, said point being, the northwest comer of Block 2 of said
Quorum addition, also being the intersection of the south right-of-way line of
Belt Line Road (100 foot right-of-way);

THENCE South 01DEG. 30'57" East for a distance of 1,014.57 feet to an iron rod
found for the POINT OF BEGINNING of the herein described tract;

THENCE North 88DEG. 29'03" East along the southerly line of a tract of land
conveyed to Crow and Associates, Inc., by deed recorded in Volume 79136, Page
2865 of the Deed Records of Dallas County, Texas, a distance of 578.65 feet to
an iron rod found for comer in the westerly line of Quorum Drive (variable
width);

THENCE in a southerly and southwesterly direction continuing along the westerly
line of Quorum Drive and along a curve to the right whose tangent bears South
3DEG. 14'14" East and having a radius of 777.43 feet, a central angle of 17DEG.
32'32", and an arc length of 238.03 feet to an iron rod found for the end of
said curve to the right;

THENCE South 14DEG. 18'18" West continuing along said westerly line of Quorum
Drive a distance of 207.07 feet to an iron rod found for corner;

THENCE South 89DEG. 46'47" West along the northerly line of a tract of land
conveyed to Richards Group, Inc. By deed recorded in Volume 79120, Page 865 of
the Deed Records of Dallas County, Texas, a distance of 493.22 feet to an iron
rod found for comer in the westerly line of Block 2 of the Quorum;

THENCE North 1DEG. 30'57" West along said westerly line of Block 2 a distance of
423.38 feet to the POINT OF BEGINNING and containing 235,285 square feet or
5.4014 acres.

                                     E-1
<PAGE>

                                     EXHIBIT F

                             FIRST RIGHT OF REFUSAL SPACE

       Provided Tenant is not in default under the Lease and provided Tenant or
an Affiliate thereof is in occupancy of the Premises and has not otherwise
assigned or sublet it, Tenant or an Affiliate thereof (but not a non-Affiliated
assignee or subtenant of Tenant) shall have the continuing right, subject to the
terms below, to Lease any portion of the space located on the first (1st),
seventh (7th), and eighth (8th) floors of the Building and outlined on the floor
plan attached hereto as EXHIBIT F-1 and labeled "First Right of Refusal Space"
(herein so called) that is either vacant on the Commencement Date or becomes
available for lease during the Tern of the Lease before it is leased to any
third party. NOTWITHSTANDING ANYTHING CONTAINED IN THIS EXHIBIT TO THE CONTRARY,
TENANT'S RIGHTS PURSUANT TO THIS EXHIBIT ARE SUBJECT AND SUBORDINATE TO ANY AND
ALL RIGHTS OF FIRST REFUSAL TO THE FIRST RIGHT OF REFUSAL SPACE WHICH ARE IN
EFFECT AS OF THE DATE OF THIS LEASE.

       Upon written request from Tenant, Landlord shall deliver to Tenant a
written list of all available spaces in the Building; provided, however,
Landlord shall not be obligated to provide such list more than once every six
(6) months during the initial Term of this Lease. In the event any third party
expresses interest in leasing all or any portion of the First Right of Refusal
Space during the period of time commencing on the Commencement Date and expiring
on the first (1st) anniversary of the Commencement Date which Landlord is
prepared to accept by entering into a lease with the proposed tenant for such
First Fight of Refusal Space, Landlord shall offer the First Right of Refusal
Space to Tenant upon the same terms (at the then current Base Rent) and
conditions of this Lease, including improvement allowances and any adjustments
thereto described below, provided that the expiration date of the lease with
respect to the First Fight of Refusal Space shall be coterminous with the
initial term of this Lease and Landlord and Tenant shall enter into an amendment
of this Lease to reflect the inclusion of the First Right of Refusal Space as a
part of the Premises demised pursuant to this Lease within five (5) business
days after Landlord has delivered such notice to Tenant. The Tenant improvement
allowance referred to above which applies to First Right of Refusal Space
exercised prior to the first (1st) anniversary of the Commencement Date shall
equal the $12.62 Leasehold Improvement Allowance provided to Tenant for the
primary Premises which remains if such Allowance had been amortized on a
straight-line basis over the initial term of the Lease. For instance, should the
First Right of Refusal Space be exercised with sixty (60) months remaining in
the initial term of the Lease, the following formula would apply: $12.62/68
months X 60 months = $11.14 improvement allowance for the First Right of Refusal
Space. In the event that Tenant fails or refuses to exercise such right of
refusal within such five (5) day period, then Tenant's rights under this
paragraph with respect to the First Right of Refusal Space so offered shall
terminate and Landlord shall thereafter be able to lease the First Right of
Refusal Space so offered to any third party on the same terms offered to Tenant.
In the event any third party expresses interest in leasing all or any portion of
the First Right of Refusal Space during the period commencing after the first
(1st) anniversary of the Commencement Date and expiring at the end of the Term
of this Lease which Landlord is prepared to accept by entering into a lease with
the proposed tenant for such First Right of Refusal Space, Landlord shall offer
the First Right of Refusal Space to Tenant upon the same terms and conditions as
Landlord intends to offer to the proposed tenant provided that the expiration of
the term of the lease of the First Right of Refusal Space shall be coterminous
with the Term of this Lease. Tenant shall notify Landlord in writing of the
acceptance of such offer within five (5) business days after Landlord has
delivered such offer to Tenant specifying that such First Right of Refusal Space
has been accepted by Tenant and is a part of the Premises demised pursuant to
the Lease for the remainder of the Term and containing other appropriate terms
and conditions relating to the addition of the First Right of Refusal Space to
this Lease (including

                                     E-1
<PAGE>

specifically any increase or adjustment of the Rent as a result of such
addition). In the event that Tenant does not notify Landlord in writing of
its acceptance of such offer within such five (5) business day period, then
Tenant's rights under this paragraph with respect to the First Right of
Refusal Space so offered shall terminate and Landlord shall thereafter be
able to lease the First Right of Refusal Space or any portion thereof to any
third party on the same terms offered to Tenant. Any termination of the Lease
shall terminate all rights of Tenant with respect to the First Right of
Refusal Space. The rights of Tenant with respect to the First Right of
Refusal Space shall not be severable from the Lease, nor may such rights be
assigned or conveyed in connection with any permitted non-Affiliated
assignment of the Lease. Landlord's consent to any assignment of the Lease
shall not be construed as allowing an assignment or a conveyance of such
rights to any assignee. Nothing herein contained should be construed so as to
limit or abridge Landlord's ability to deal with the First Right of Refusal
Space or to lease the First Right of Refusal Space to other tenants,
Landlord's sole obligation being to offer, and if such offer is accepted, to
deliver the First Right of Refusal Space to Tenant in accordance with this
Exhibit. If Landlord materially changes the terms of the offer to the
proposed tenant and such changes are more favorable to the proposed tenant
than those contained in the first right of refusal notice to Tenant, then
Landlord shall submit such differing terms to Tenant for acceptance by Tenant
prior to entering into a lease with such third party. Tenant's failure to
exercise its rights with respect to First Right of Refusal Space on one
occasion shall not prevent Tenant from exercising such rights to the same
First Right of Refusal Space when such First Right of Refusal Space becomes
available for lease by Landlord again.

       The Lease shall not be void or voidable, nor shall Landlord be liable to
Tenant for any loss or damage resulting from any delay in delivering possession
of the First Right of Refusal Space to Tenant, but abatement of the Base Rental
attributable to the First Right of Refusal Space from the date of Tenant's
acceptance of Landlord's offer with respect to the First Right of Refusal offer
to the date of actual delivery of the First Right of Refusal Space shall
constitute full settlement of all claims that Tenant might have against Landlord
by reason of the First Right of Refusal Space not being delivered upon the date
of Tenant's acceptance of Landlord's offer.

                                     E-2
<PAGE>

                                     EXHIBIT G

                                   RENEWAL OPTIONS

       Provided that no event of default exists under any term or provision
contained in this Lease and no condition exists which with the passage of time
or the giving of notice or both would constitute an event of default pursuant to
this Lease and provided that Tenant has continuously occupied the Premises for
the Permitted Use during the Term of this Lease, Tenant (but not any assignee or
subtenant of Tenant) shall have, and is hereby given, two (2) options (each, a
"Renewal Option") to renew and to extend the term of this Lease, each Renewal
Option to follow consecutively upon the expiration of the initial Term of this
Lease (or the immediately preceding Renewal Term [hereinafter defined], if
applicable). Each Renewal Option shall be for a term (determined by Tenant) of
not less than thirty-six (36) months and not more than sixty (60) months (a
"Renewal Term") and shall be exercised, if at all, by Tenant giving written
notice thereof to Landlord at least nine (9) months prior to the expiration date
of the initial Term or the then current Renewal Term, as the case may be.
Tenant's written notice to Landlord exercising a Renewal Option shall state
Tenant's desired term of such renewal in accordance with the time parameters
stated above. The renewal and extension of this Lease for any Renewal Term shall
be under the same terms, conditions and covenants contained in the Lease, except
that (a) no abatements or other concessions, if any, applicable to the initial
Term shall apply to any Renewal Term; (b) the Base Rent shall be equal to the
Prevailing Market Rent (hereinafter defined); (c) Tenant shall have no option to
renew this Lease beyond the expiration of the second Renewal Term (provided that
Tenant exercised its option with respect to the first Renewal Term and has
otherwise satisfied the requirements of this Exhibit); and (d) all leasehold
improvements within the Premises shall be provided in their then existing
condition (on an "as is" basis) at the time the Renewal Term in question
commences. Failure by Tenant to notify Landlord in writing of Tenant's election
to exercise the Renewal Options herein granted within the time limits set forth
for such exercise shall constitute a waiver and termination of such Renewal
Options.

       As used herein, the term "Prevailing Market Rent" means what a non-equity
tenant would pay and receive and on what a landlord of a comparable office
building (with similar amenities) would accept and give at arm's length as rent
concessions, expense, escalations, tenant improvement allowances, refurbishment
allowances, other allowances, brokerage commissions, inducements and other
economic conditions for the lease of space comparable to the Premises. The
determination of such Prevailing Market Rent shall, for all applications in this
Lease, be made using the following procedure:

       1.     Whenever, pursuant to the terms of this Lease, a determination
              must be made of revailing Market Rent, Landlord shall provide to
              Tenant in writing Landlord's reasonable determination of such
              Prevailing Market Rent within fifteen (15) days after receipt of
              Tenant's written request therefor. If Tenant accepts such
              determination by Landlord in writing, or if Tenant shall not have
              notified Landlord of its objection to such determination in
              writing, both within fifteen (15) days following Tenants receipt
              of such determination, then such determination by Landlord of the
              Prevailing Market Rent for that applicable portion of the Lease
              shall irrevocably become the Prevailing Market Rent.

       2.     If Tenant notifies Landlord, within fifteen (15) days following
              its receipt of Landlord's determination of Prevailing Market Rent,
              that it objects to such determination as not accurately reflecting
              such prevailing market rental rate ("Tenant's Notice of
              Objection"), then Landlord's determination of Prevailing Market
              Rent referred to in paragraph 1 above shall thereafter not be
              effective, and instead the following procedure shall be
              implemented to determine Prevailing Market Rent:

                                     G-1
<PAGE>

              (a)    Within fifteen (15) days following Landlord's receipt of
                     Tenant's Notice of Objection, Landlord shall select and
                     notify Tenant of its selection of, an independent real
                     estate broker from a recognized commercial real estate
                     brokerage firm knowledgeable in the commercial real estate
                     market of the Quorum, Addison, Texas, sub-market (the
                     "Landlord's Market Broker"). Within fifteen (15) days
                     following Landlord's selection of Landlord's Market Broker,
                     Landlord shall cause such broker to analyze the
                     then-existing market conditions, prepare and deliver to
                     Landlord and Tenant such broker's determination of the
                     Prevailing Market Rent for the space to be leased by Tenant
                     within the Building to which such Prevailing Market Rate
                     shall apply. If Tenant accepts in writing such
                     determination of Prevailing Market Rent presented by
                     Landlord's Market Broker, or if Tenant shall not have
                     notified Landlord of its objection to such determination,
                     in writing, both within fifteen (15) days following
                     Tenant's receipt of such determination by Landlord's Market
                     Broker, then such determination by Landlord's Market Broker
                     of the Prevailing Market Rent for that applicable portion
                     of the Lease shall irrevocably become the Prevailing Market
                     Rent.

              (b)    If Tenant notifies Landlord, within fifteen (15) days
                     following its receipt of Landlord's Market Broker's
                     determination of the Prevailing Market Rent, that it
                     objects to such determination as not accurately reflecting
                     such prevailing market rental rate ("Tenant's Notice of
                     Objection to Landlord's Market Broker's Determination"),
                     then the following procedure shall be implemented to
                     determine Prevailing Market Rent:

                     (i)    Within fifteen (15) days following Tenant's giving
                            or delivering to Landlord the Tenant's Notice of
                            Objection to Landlord's Market Broker's
                            Determination, Tenant shall select, and notify
                            Landlord of its selection of, an independent real
                            estate broker from a recognized commercial real
                            estate brokerage firm knowledgeable in the
                            commercial real estate market of the Quorum,
                            Addison, Texas, sub-market (the "Tenant's Market
                            Broker").  Within fifteen (15) days following
                            Tenant's selection of Tenant's Market Broker, Tenant
                            shall cause such broker to analyze the then-existing
                            market conditions, and prepare and deliver to
                            Landlord and Tenant such broker's determination of
                            the Prevailing Market rent for the space to be
                            leased by Tenant within the Building to which such
                            Prevailing Market Rate shall apply.  If Landlord
                            accepts in writing such determination of Prevailing
                            market Rent presented by Tenant's market Broker, of
                            if Landlord shall not have notified Tenant of its
                            objection to such determination, in writing, both
                            within fifteen (15) days following Landlord's
                            receipt of such determination of Prevailing Market
                            Rent presented by Tenant's Market Broker, or if
                            Landlord shall not have notified Tenant of its
                            objection to such determination by Tenant's Market
                            broker, then such determination by Tenant's Market
                            Broker of the Prevailing Market Rent for that
                            applicable portion of the Lease shall irrevocably
                            become the Prevailing Market Rent.

                     (ii)   If Landlord notifies Tenant, within fifteen (15)
                            days following its receipt of Tenant's Market
                            Broker's determination of the Prevailing Market
                            Rent, that it objects to such determination as not
                            accurately reflecting

                                     G-2
<PAGE>

                            such prevailing market rental rate ("Landlord's
                            Notice of Objection to Tenant's Market Broker's
                            Determination"), then Landlord shall, within five
                            (5) days thereafter, direct both Landlord's
                            Market Broker and Tenant's Market Broker to
                            select within ten (10 days thereafter, and notify
                            Landlord and Tenant of their selection of, a
                            third independent real estate broker from a
                            recognized commercial real estate brokerage firm
                            knowledgeable in the commercial real estate
                            market of the Quorum, Addison, Texas, sub-market
                            (the "Third Market Broker").  Within fifteen (15)
                            days following such selection of the Third Market
                            Broker, such Broker shall analyze the
                            then-existing market conditions, prepare and
                            deliver to landlord, Tenant, landlord's Market
                            Broker, and Tenant's market Broker such Third
                            Market Broker's determination of the Prevailing
                            Market Rent for the space to be leased by Tenant
                            within the Building to which such Prevailing
                            Market Rate shall apply.  If the third Market
                            Broker's determination of Prevailing Market Rent
                            is a number between (x) the rental rate
                            determined by Landlord's Market Broker, augmented
                            five percent (5%) both higher and lower from such
                            rental rate, and (y) the rental rate determined
                            by Tenant's Market Broker, augmented five percent
                            (5%) both higher and lower from such rental rate,
                            then such Third Market Broker's determination of
                            Prevailing Market Rent shall be irrevocably
                            binding upon both Landlord and Tenant.  However,
                            if the Third Market Broker's determination of
                            Prevailing Market Rent is a number not between
                            (x) and (y) from the previous sentence, then the
                            final, irrevocable determination of Prevailing
                            Market Rent which shall be binding upon both
                            Landlord and Tenant, will be calculated by adding
                            together the two closest appraisals of the three
                            determinations from the three brokers, and
                            dividing such sum by two.  Both Landlord and
                            Tenant acknowledge that the determination of
                            Prevailing Market Rent which is derived from such
                            procedure shall be irrevocably binding upon both
                            Landlord and Tenant.

              (c)    Notwithstanding any provisions elsewhere in this Lease
                     allocating the payment of expenses, Landlord agrees to pay
                     the expenses associated with the services of Landlord's
                     Market Broker, Tenant agrees to pay the expenses associated
                     with the services of Tenant's Market Broker, and both
                     Landlord and Tenant agree to jointly pay the expenses
                     associated with the services of the Third Market Broker.

       Upon exercise of a Renewal Option by Tenant and subject to the conditions
set forth hereinabove, the Lease shall be extended for the period of such
applicable Renewal Term without the necessity of the execution of any further
instrument or document, although if requested by either party, Landlord and
Tenant shall enter into a written agreement modifying and supplementing the
Lease in accordance with the provisions hereof.  Any termination of the Lease
during the initial Lease Term shall terminate all rights to the second Renewal
Option.  The renewal rights of Tenant hereunder shall not be severable from the
Lease, nor may such rights be assigned or otherwise conveyed in connection with
any permitted non-Affiliated assignment of the Lease.  Landlord's consent to any
assignment of the Lease shall not be construed as allowing an assignment of such
rights to any assignee.

                                     G-3
<PAGE>

                                     EXHIBIT H

                     AIR CONDITIONING AND HEATING SPECIFICATION

The following represents the required office environment of the Tenant.

The entire office area shall be heated and air conditioned by a combination
heating/cooling unit and a duct system, to maintain for heating 70DEG. F inside
when the outside temperature is 0DEG. F and for cooling inside 75DEG. F dry bulb
with a 50% relative humidity when outside temperature is 95DEG. F and 78DEG. F
wet bulb.  Air conditioning specifications are stated on the basis of doors and
windows being closed, as well as all glass areas in the air conditioned premises
being provided with vertical window blinds, shades or drapes which shall be
closed, depending on the position of the sun.

                                     H-1<PAGE>

                                                 Re:    14901 Quorum Drive
                                                        Dallas, Texas

                          FIRST AMENDMENT TO LEASE AGREEMENT

THE STATE OF TEXAS          )
                            )      KNOW ALL MEN BY THESE PRESENTS:
COUNTY OF DALLAS            )

       THIS FIRST AMENDMENT TO LEASE AGREEMENT (this "AMENDMENT") has been
executed effective as of (but not necessarily on) the 23rd day of September,
1999, by CARRAMERICA REALTY L.P., a Delaware limited partnership ("LANDLORD")
and OBJECTSPACE, INC., a Delaware corporation ("Tenant").

                                  R E C I T A L S:

       A.     Landlord and Tenant have heretofor executed that certain Lease
Agreement (the "LEASE"), dated as of April, 1997, pursuant to which Tenant
leased from Landlord certain premises containing approximately 28,606 rentable
square feet (the "ORIGINAL PREMISES") in that certain building known as 14901
Quorum Drive, Dallas, Texas, and more particularly described in the Lease (the
"BUILDING"). Unless otherwise defined herein, all initially capitalized terms
will have the respective meanings assigned thereto in the Lease.

       B.     Landlord and Tenant desire to execute this Amendment in order to
evidence their agreement to (i) reduce the original Premises by 8,606 rentable
square feet contained in Suite 125 of the Building (the "REDUCED PREMISES"); and
(ii) make certain other amendments to the Lease, all as more particularly set
forth in this Amendment.

       NOW THEREFORE, in consideration of the foregoing and other good and
valuable consideration, the receipt and sufficiency of which are hereby
acknowledged, Landlord and Tenant agree as follows:

                                     Article I

                                CERTAIN AMENDMENTS

       SECTION 1.01. REDUCED PREMISES. As of September 23, 1999 (the "REDUCTION
DATE"), and subject to the contingencies set forth in this Amendment, the
Original Premises will be reduced by 8,606 rentable square feet, representing
the square footage contained in Suite 125. The Original Premises, as so reduced,
are outlined on EXHIBIT B, page B-1 of the Lease, containing 20,000 rentable
square feet in Suite 900 of the Building and are hereinafter referred to as the
"PREMISES."  Page B-2 of the EXHIBIT B is hereby deleted. As a result, the
Premises covered under the Lease will equal approximately 20,000 rentable square
feet, representing the sum of the 28,606 rentable square feet included within
the Original Premises, less the 8,606 rentable square feet contained within the
Reduced Premises. Tenant shall remain liable for all Rent and Additional Rent
obligations accruing under the Lease with respect to the Reduced Premises prior
to the Reduction Date. Any of Tenant's rights to parking associated with the
Reduced Premises (together with any charges therefor) are hereby terminated.

FIRST AMENDMENT TO LEASE AGREEMENT - Page 1 of 3
<PAGE>

       SECTION 1.02.  REMAINING PREMISES.  The Lease as to the Premises will
continue in full force and effect in accordance with the terms and conditions
set forth in the Lease, except that (a) the monthly  Base Rent from October 1,
1999, through March 31, 2003, shall be $34,166.66 per month, payable monthly, in
advance, without set off or deduction whatsoever, and (b) Tenant's obligations
with respect to Additional Rent shall be reduced proportionately.

       SECTION 1.03 . SURRENDER/VACATE.  Except to the extent otherwise agreed
to by Valtech (defined below), on or before the Reduction Date, Tenant agrees to
vacate and abandon the Reduced Premises and to remove, at Tenant's sole cost,
all office equipment and supplies, furniture and other personal property, each
to the extent owned by Tenant and located within, and readily removable from,
the Reduced Premises. Except to the extent otherwise agreed to by Valtech
(defined below), Tenant must deliver the Reduced Premises to Landlord in
broom-clean condition and restore and otherwise repair, at Tenant's sole cost,
all damage caused to the Reduced Premises as a result of any such removal.

       SECTION 1.04. COMMISSIONS.  Landlord and Tenant each represent to the
other that no brokers have been or will be involved in this Amendment. Landlord
and Tenant hereby indemnify each other from the payment of any commissions
resulting from the acts of such party, but not otherwise.

       SECTION 1.05. CONTINGENCY. This Amendment is contingent upon Landlord
entering into a lease (the "NEW LEASE") with Valtech Technologies, Inc.
("VALTECH") for the Reduced Premises on terms and conditions acceptable to
Landlord, in Landlord's sole discretion, and Landlord obtaining a Guaranty (the
"GUARANTY") for such lease obligations from Valtech S.A., in form and substance
acceptable to Landlord, in Landlord's sole discretion. If Landlord has not
entered into the New Lease by October 1, 1999, and obtained the Guaranty by
October 21, 1999, on either such occasion, at Landlord's election, this
Amendment shall be null and void, except with respect to the next sentence of
this Section 105. In the event that the contingencies are not satisfied within
the time periods set forth above, i.e., a New Lease is not entered into and/or
Landlord does not receive the Guaranty, Landlord agrees to waive its right to
recapture the Reduced Premises if Tenant and Valtech (which Landlord hereby
approves as an acceptable subtenant) enter into a sublease of the Reduced
Premises on or before October 31, 1999, with an effective date on or before
October 31, 1999, in form reasonably acceptable to Landlord and on substantially
the terms and conditions currently set forth in the New Lease.

       SECTION 1.06. FURTHER AMENDMENTS. The Lease shall be and hereby is
further amended wherever necessary, even though not specifically referred to
herein, in order to give effect to the terms of this Amendment. Tenant's rights
with respect to the first (1st) floor First Right of Refusal Space described in
EXHIBIT F to the Lease are hereby deleted. Tenant's rights with respect to the
seventh (7th) and eighth (8th) floor First Right of Refusal Space shall be
retained by Tenant in accordance with EXHIBIT F.

                                     Article II

                                    MISCELLANEOUS

       SECTION 2.01. RATIFICATION. The Lease, as amended hereby, is hereby
ratified, confirmed and deemed in full force and effect in accordance with its
terms. Each party represents to the other that such party (a) is currently
unaware of any default by the other party under the Lease; and (b) has full
power and authority to execute and deliver this Amendment and this Amendment
represents a valid and binding obligation of such party enforceable in
accordance with its terms.

FIRST AMENDMENT TO LEASE AGREEMENT - Page 2 of 3
<PAGE>

       SECTION 2.02. NOTICES. All notices to be delivered to Landlord under the
Lease or otherwise with respect to the Premises shall, unless Landlord otherwise
notifies Tenant, be delivered to Landlord in accordance with the Lease at the
following addresses:

              CarrAmerica Realty, L.P.
              c/o CarrAmerica Realty Corporation
              15950 N. Dallas Parkway, Suite 300
              Dallas, TX 75248

              with a copy to:

              CarrAmerica Realty Corporation
              1850 K Street, N. W.
              Suite 500
              Washington, D.C. 20006
              Attn.: Lease Administration

       SECTION 2.03. GOVERNING LAW. This Amendment shall be governed by and
construed in accordance with the laws of the State of Texas.

       SECTION 2.04. COUNTERPARTS. This Amendment may be executed in multiple
counterparts each of which is deemed an original but together constitute one and
the same instrument. This Amendment may be executed by facsimile and each party
has the right to rely upon a facsimile counterpart of this Amendment signed by
the other party to the same extent as if such party had received an original
counterpart.

       IN WITNESS WHEREOF, this Amendment has been executed as of (but not
necessarily on) the date and year first above written.

                                   LANDLORD:

                                   CARRAMERICA REALTY L.P.,
                                   a Delaware limited partnership

                                   By:   CarrAmerica Realty G.P.
                                         Holdings, Inc.,
                                         its general partner

                                         By: /s/ PHILIP L. HAWKINS
                                            ------------------------------------
                                         Print Name:   Philip L. Hawkins
                                                     ---------------------------
                                         Print Title:  Executive Vice President
                                                     ---------------------------

                                   TENANT:

                                   OBJECTSPACE, INC.,
                                   a Delaware corporation

                                   By:   /s/ KENNETH J. OVERTON
                                      ----------------------------------------
                                   Print Name:   Kenneth J. Overton
                                              --------------------------------
                                   Print Title:  VP, Enterprise Solutions
                                               -------------------------------

FIRST AMENDMENT TO LEASE AGREEMENT - Page 3 of 3

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