Document:

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                                                                   Exhibit 10.14

                              TAX SHARING AGREEMENT

               This AGREEMENT is dated as of July 31, 2000, between Siemens
Corporation, a Delaware corporation ("Siemens"), and Unisphere Solutions, Inc.,
a Delaware corporation ("USI").

                                   WITNESSETH

               WHEREAS, Siemens and USI have joined in the filing of a
consolidated income tax return for a group of affiliated companies of which
Siemens is the common parent and USI is a member (the "Siemens Affiliated
Group"); and

               WHEREAS, it is the intent and desire of Siemens and USI in this
Agreement to provide for the amount and time of payments by USI to Siemens and
for the amount and time of payments by Siemens to USI with respect to U.S.
federal, state and local income taxes;

               NOW, THEREFORE, Siemens and USI, intending to be legally bound
hereby, and in consideration of the mutual covenants herein contained, agree as
follows:

1. DEFINITIONS

         (a) "Code" means the Internal Revenue Code of 1986, as amended and in
effect from time to time, or any law which may be a successor thereto. A
reference to any section of the Code means such section (or comparable provision
of a successor law) as in effect from time to time.

         (b) "Former Member" shall mean USI or any USI Subsidiary which is no
longer included in any Siemens Consolidated Tax Return.

         (c) "IPO" means a private placement or initial public offering of
shares of USI or any direct or indirect subsidiary of USI.

         (d) "Separate Return Tax Liability" shall have the meaning ascribed
thereto in Paragraph 3(b)(i).

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         (e) "Siemens Consolidated Return Liability" shall have the meaning
ascribed thereto in Paragraph 3(a).

         (f) "Siemens Consolidated Tax Return" shall have the meaning ascribed
thereto in Paragraph 2(a).

         (g) "Tax" or "Taxes" means U.S. federal, state and local income taxes,
together with interest, penalties and other additions thereto, imposed by the
relevant Taxing Authority.

         (h) "Tax Attribute" means any net operating loss, net capital loss,
investment tax credit, foreign tax credit, targeted jobs tax credit, credit for
research activities, charitable deduction, deduction for worthless stock or
securities or any other credit or tax attribute (or carryforward or carryback
thereof) which could reduce any Tax;

         (i) "Taxing Authority" means the Internal Revenue Service ("IRS") or
any other domestic governmental authority responsible for the administration of
any Tax.

         (j) "Tax Liability" shall have the meaning ascribed thereto in
Paragraph 3(b)(ii).

         (k) "Tax Return" means any return, filing, or other document required
to be filed, including requests for extensions of time, filings made with
estimated Tax payments, claims for refund and amended returns that may be filed
for any taxable period (or portion thereof) with any Taxing Authority in
connection with any Tax or Taxes (whether or not payment is required to be made
with respect to such filing).

         (l) "USI Subsidiary" means a corporation, or any other entity which is
classified as a corporation for U.S. federal income tax purposes, which is
controlled, directly or indirectly, by USI.

         (m) "Utilized Tax Attributes" shall have the meaning ascribed thereto
in Paragraph 4(b).

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2. SIEMENS CONSOLIDATED TAX RETURN

         (a) Subject to Paragraph 8 hereof, Siemens shall continue to file
consolidated income Tax Returns pursuant to Section 1501 of the Code or similar
provisions of any state or local law, including any combined filing provisions
(each a "Siemens Consolidated Tax Return")). In connection therewith, USI and
the USI Subsidiaries shall be included in the Siemens Consolidated Tax Returns
until such time as USI or a USI Subsidiary ceases to be eligible to be so
included (which disaffiliation of USI or the USI Subsidiary may be the result of
actions taken by Siemens at its sole discretion).

         (b) For any taxable year (or portion thereof) in which USI is included
as a member in a Siemens Consolidated Tax Return, Siemens shall be responsible
for managing the filing of the Siemens Consolidated Tax Returns and for
determining the appropriate strategy for handling audits and disputes with Tax
Authorities. Except as otherwise expressly provided herein, Siemens shall be
responsible for the final determination of all computations required under this
Agreement. Unless agreed in advance by Siemens, USI and the USI Subsidiaries
shall not take any Tax reporting position or claim any Tax Attribute, or agree
with a Taxing Authority as to any such position or the allowance of a Tax
Attribute, which is inconsistent with a prior Tax reporting position or claim of
a Tax Attribute by Siemens or any entity included in a Siemens Consolidated Tax
Return in which USI or a USI Subsidiary is included as a member.

         (c) USI and the USI Subsidiaries shall furnish Siemens upon request
with Tax Return packages, work papers, and other requested information and
documentation relevant for the preparation of the Siemens Consolidated Tax
Returns and other U.S. federal, state and local Tax Returns (the "Tax Data"). At
least 45 days prior to the due date (including extensions) of a Siemens
Consolidated Tax Return, Siemens shall provide a copy of such Tax Return to USI
and permit USI to verify that the Tax Data submitted by USI and the USI
Subsidiaries is accurately reflected on such Tax Return. Siemens will provide
USI with a schedule with respect to each Siemens Consolidated Tax Return
setting forth the

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differences, if any, between the Tax Data submitted by USI and the USI
subsidiaries and the information reported on such Tax Return (each a "Tax
Schedule").

         (d) If USI owns or acquires, directly or indirectly, a USI Subsidiary,
USI will cause the USI Subsidiary to become a party to this Agreement and to
agree to be bound by its terms and provisions.

3. CALCULATION OF TAX LIABILITY

         (a) Except to the extent otherwise provided in this Agreement, Siemens
shall be liable for all Taxes due in respect of all Siemens Consolidated Tax
Returns, subject to reimbursement from USI as contemplated by this Paragraph 3
(the "Siemens Consolidated Return Liability").

         (b) The portion of the Siemens Consolidated Return Liability which is
payable by USI and the USI Subsidiaries shall be determined in the following
manner:

                  (i) Commencing with the period beginning on the date of
closing of an IPO, with respect to any taxable period (or portion thereof)
during which USI is included in any Siemens Consolidated Tax Return, the Tax
Liability (as defined below) of USI and the USI Subsidiaries for such taxable
period for such Tax Return shall be determined on a hypothetical separate Tax
Return basis as if USI and the USI Subsidiaries were not included in such
Siemens Consolidated Tax Return commencing on the date of the IPO. To the extent
USI and/or any of the USI Subsidiaries could have filed a separate consolidated
or combined Tax Return for such taxable period, the hypothetical separate Tax
Liability shall be computed on such a basis. (This hypothetical consolidated or
combined Tax Liability, together with the hypothetical separate Tax Liability of
USI and any USI Subsidiaries which could not be included in the hypothetical
consolidated or combined Tax Return, is referred to as the "Separate Return Tax
Liability.")

                  (ii) For purposes of subparagraph (i), "Tax Liability" shall
be the federal, state and local Tax liability determined in a manner consistent
with the computation of the Siemens Consolidated

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Return Liability based on taxable income reduced by any loss carryforwards and
dividends received deduction, multiplied by the applicable Tax rate, less any
Tax credits, plus any alternative minimum Tax, as defined in Section 55 of the
Code or any similar state or local Tax, plus or minus any additional adjustments
required to compute the final Tax Liability under the appropriate Tax law. In
addition, the following modifications shall apply: (A) where the Siemens
Consolidated Return Liability with respect to state or local Taxes is computed
using an apportionment ratio based on the combined factors of the entities
included in such Tax Return (the "group apportionment ratio"), the apportionment
of net income or loss to USI or the relevant USI Subsidiary shall be
accomplished using the group apportionment ratios and not the separate
apportionment ratio of such entity, (B) items of income, expense, gain or loss
that are determined on a consolidated basis in the calculation of Siemens
Consolidated Tax Return Liability shall retain the character resulting in the
consolidated computation for purposes of determining Tax Liability (such as
characterizations under Section 1231 of the Code), (C) elections as to tax
credits and tax computations which may have been different from the consolidated
treatment if separate returns were filed shall be made on an annual basis by
Siemens; (D) estimated Tax payments made pursuant to Paragraph 4(a) of this
Agreement shall not be included in the computation of Separate Return Tax
Liability; and (E) to the extent Siemens makes a payment in respect of a Tax
Attribute pursuant to Paragraph 4(b), such Tax Attribute shall be excluded in
determining present or future Separate Return Tax Liability.

                  (iii) In the case of a relevant taxable period which is less
than a complete taxable year, the Separate Return Tax Liability and Tax
Attributes of USI and the USI Subsidiaries shall be determined by prorating the
Tax Liability or Tax Attributes for the complete taxable year based on the ratio
of the number of days included in such taxable period to the number of days in
the taxable year or by such other method as is agreed by both Siemens and USI.

         (c) During all periods in which USI is included in a Siemens
Consolidated Tax Return, Siemens shall calculate the Separate Return Tax
Liability on a quarterly basis. In addition, Siemens shall

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make a final calculation of the Separate Return Tax Liability for the taxable
year and, upon written request, shall submit such calculation to USI for its
review by the later of seven days after the request or 15 days prior to the due
date (including extensions) for the filing of the relevant Siemens Consolidated
Tax Return for such taxable year. For periods after USI ceases to be included in
any Siemens Consolidated Tax Return and computations of the Tax Liabilities of
USI or any USI Subsidiary are relevant under Paragraphs 3, 4 or 5 of this
Agreement, USI shall prepare a computation of the relevant actual and
hypothetical Tax Liabilities of it and the USI Subsidiaries (or a computation
similar to the Separate Return Tax Liability computation if USI is a member, but
not the parent corporation, of a separate group filing consolidated Tax Returns)
and submit such computations and supporting documentation to Siemens for its
review. The parties agree that in the event of a disagreement in such
computations which is not resolved within 90 days, they will submit their
dispute to a mutually satisfactory "big five" accounting firm (or other mutually
acceptable accounting firm) for its determination, which determination shall be
final and binding on both parties.

4. PAYMENT

         (a) USI shall pay to Siemens the amount of the Separate Return Tax
Liability for USI and the USI Subsidiaries, as determined under Paragraph 3,
subject to any adjustments under Paragraph 6 of this Agreement. Payments shall
be made no later than the business day immediately preceding the business day
which is the due date (including extensions) for Siemens' payment of estimated
U.S. federal, state or local income Tax, as applicable. Such payments shall be
credited toward the Separate Return Tax Liability for such taxable year. Within
60 days prior to the filing of a Siemens Consolidated Tax Return, USI shall pay
to Siemens the unpaid portion of its Separate Return Tax Liability, if any, for
such taxable year (or portion thereof) with respect to such Tax Return. In the
event the payments of estimated Tax to Siemens for any taxable year exceed the
Separate Return Tax Liability for such taxable year, the excess shall be
refunded by Siemens to USI within 60 days after the due date (including
extensions) of relevant Siemens Consolidated Tax Return.

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         (b) Siemens shall pay to USI the amount of any reduction of Siemens
Consolidated Tax Liability attributable to any Tax Attributes of USI or the USI
Subsidiaries attributable to taxable periods after the date of closing of the
IPO and which serve or have served to reduce or eliminate the Siemens
Consolidated Return Liability, but which were not applied to reduce or eliminate
the Separate Return Tax Liability for any taxable period (the "Utilized Tax
Attributes"); provided, however, that Siemens shall be liable for such a payment
only if and to the extent that USI or any USI Subsidiary would have been able to
use such Tax Attribute to reduce or eliminate its Separate Return Tax Liability
(if USI is still included in a Siemens Consolidated Tax Return) or its actual
Tax liability (if USI is not included in a Siemens Consolidated Tax Return) had
such Tax Attribute not already been applied to reduce or eliminate the Siemens
Consolidated Return Liability. Such payment shall be due and payable by Siemens
on the due date (including extensions) of the Siemens Consolidated Tax Return or
the separate Tax Return on which USI, or the USI Subsidiary whose Tax Attribute
was absorbed, would have been able to use the Utilized Tax Attribute on a
separate return basis. The amount of such payment shall be equal to the Tax
benefit that USI or the USI Subsidiary, as applicable, would have received on a
separate return basis in the taxable year in which such Tax benefit could have
been used.

               For the avoidance of doubt, in determining the taxable period in
which a Former Member could have used the Utilized Tax Attribute on a separate
return basis, any Tax Attribute incurred by the Former Member after it ceased to
be included in a Siemens Consolidated Tax Return, shall be applied first against
the taxable income of such Former Member.

         (c) Notwithstanding any other paragraph or provision of this Agreement,
if Siemens claims or uses a Tax Attribute on a Siemens Consolidated Tax Return
which arose prior to the date of the first IPO and subsequently it is determined
by the parties or a Taxing Authority that all or a portion of such Tax Attribute
is properly attributable or allowable to USI or a USI Subsidiary on or after the
date of such IPO, then (i) if such Tax Attribute is claimed or used while USI is
still included in a Siemens Consolidated Tax Return, the computation of Tax
Liability under Paragraph 3(b) shall be made without

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regard to such Tax Attribute, and (ii) if all or a portion of such Tax Attribute
is claimed or used in a taxable period after USI ceases to be included in a
Siemens Consolidated Tax Return, USI shall pay to Siemens the amount of the
actual reduction in Taxes of USI or a USI Subsidiary attributable to the use of
such Tax Attribute. Such payment shall be due and payable by USI on the due date
(including extensions) of the Tax Return of USI or the USI Subsidiary on which
such Tax Attribute was claimed or used.

5. ADJUSTMENTS/CONTESTS

         (a) Siemens shall be solely responsible for, and shall have sole and
absolute discretion with respect to, claiming, agreeing to, contesting or
settling any adjustments to the Siemens Consolidated Return Liability. Siemens
shall pay any deficiencies in, or receive any refunds with respect to, any
Siemens Consolidated Return Liability for any taxable year. Siemens, on one
hand, and USI or any USI Subsidiary, on the other hand, shall promptly notify
the other in writing upon the commencement of any Tax audit, administrative or
judicial proceeding, or other similar matter (a "contest") that could affect the
Siemens Affiliated Group or USI or any USI Subsidiary. Each such notice shall
contain factual information (to the extent known) describing the asserted Tax
liability in reasonable detail and shall include copies of any notice or other
document received from the relevant Taxing Authority. Siemens shall be entitled
to conduct and control any such contest. Siemens will allow USI an opportunity
to review and comment upon any settlement, agreement, discharge or compromise
proposed by a Taxing Authority with respect to the Siemens Consolidated Return
Liability to the extent it may adversely impact the Tax liability of USI or a
USI Subsidiary. USI and the USI Subsidiaries shall cooperate and provide Siemens
reasonable access to books, records and other information needed in connection
with any contest related to periods in which USI or the relevant USI Subsidiary
was included in a Siemens Consolidated Tax Return.

         (b) In the event such adjustments are made, the amounts to be paid or
received by USI pursuant to Paragraph 4 shall be recomputed and Siemens shall
pay to USI (or any USI Subsidiary) or

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USI (or any USI Subsidiary) shall pay to Siemens, as the case may be, the amount
of any differences plus a pro rata share of any interest or penalties not later
than 90 days after the date of any such payment or receipt to or from the Taxing
Authority; provided, however, that to the extent such adjustment results from a
Tax position taken by Siemens contrary to the Tax Data provided by USI on a USI
Subsidiary, as shown on a Tax Schedule, the interest or penalties attributable
to such adjustment shall be solely for the account of Siemens.

6. Disaffiliation

         (a) If USI or any of the USI Subsidiaries ceases to be included in a
Siemens Consolidated Tax Return, this Agreement shall continue to apply with
respect to any taxable period in which the income of the Former Member is
included in a Siemens Consolidated Tax Return or in which such Former Member
uses a Tax Attribute described in Paragraph 4(c). The Former Member shall remain
liable to Siemens for any payments required under this Agreement, including, but
not limited to, payments of Tax and estimated Tax for periods in which the
Former Member's income is included in a Siemens Consolidated Tax Return and
payments attributable to adjustments referred to in Paragraph 5 of this
Agreement.

         (b) Siemens shall continue to make payments, if any, to a Former Member
pursuant to Paragraphs 4(b) and 5 of this Agreement.

7. Payment of Funds

        Payments due to or from a party under this Agreement may be netted by a
party, but no party shall be entitled to apply any amounts due to it pursuant to
this Agreement against any other amounts payable to the other party. Siemens may
designate a member to act on its behalf in receiving and disbursing funds
between or among the members. Such designation, if made in writing, shall
continue in force until rescinded.

8. Coverage

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         This Agreement shall cover all taxable periods commencing on or after
the date of closing of the first IPO and shall continue for all subsequent
taxable periods for which USI is a member of the Siemens Affiliated Group; it
being understood that, subject to the provisions of applicable law, Siemens
shall have sole and absolute discretion whether to file a Siemens Consolidated
Tax Return for any taxable period.

9. AMENDMENT; TERMINATION; SURVIVAL

         (a) This Agreement may be amended or terminated in whole or in part
only by a written instrument signed by all the parties hereto, including any
corporation that becomes a party after the effective date of this Agreement.

         (b) Paragraphs 5 and 6 shall survive the termination of this Agreement.

10. UNENFORCEABILITY

         In the event that any of the provisions of this Agreement are held to
be unenforceable or invalid by any court of competent jurisdiction, unless the
unenforceability or invalidity thereof causes a substantial departure from the
underlying intent and sense of the remainder of this Agreement, the validity and
enforceability of the remaining provision shall not be affected thereby, except
those remaining provisions of which the unenforceable or invalid provisions
comprise an integral part or from which they are otherwise clearly inseparable.
In the event any provision is held unenforceable or invalid, the parties shall
use their best efforts to agree upon an enforceable and valid provision which
shall be a reasonable substitute for such unenforceable or invalid provision in
light of the purpose of this Agreement and, upon so agreeing, shall incorporate
such substitute provision in this Agreement.

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11. CHOICE OF LAW

        This Agreement shall be governed by and construed in accordance with the
laws of the State of New York.

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

SIEMENS CORPORATION                         UNISPHERE SOLUTIONS, INC.

By: /s/ George Pompetzki                    By: /s/ John J. Connolly
    -----------------------                    ----------------------------
Name: George Pompetzki                      Name: John J. Connolly
Title: Vice President, Taxes                Title: V.P. & CFO

                                       11<PAGE>   1
                                                                   Exhibit 10.20

                                  LEASE BETWEEN

            ARTHUR J. GUTIERREZ AND JOHN A. CATALDO, CLASS A TRUSTEES
              AND HOWARD STOCK AND MARC D. LEVY, CLASS B TRUSTEES,
              ALL AS TRUSTEES OF MICHELSON FARM-WESTFORD TECHNOLOGY
          PARK TRUST, UNDER DECLARATION OF TRUST DATED OCTOBER 1, 1984,
   RECORDED WITH THE MIDDLESEX NORTH DISTRICT REGISTRY OF DEEDS IN BOOK 2863,
                                    PAGE 235

                                       AND

                            UNISPHERE SOLUTIONS, INC.

                                       FOR

          150,000 SQUARE FEET - MICHELSON FARM-WESTFORD TECHNOLOGY PARK
                             WESTFORD, MASSACHUSETTS

                                      INDEX

<TABLE>
<CAPTION>
<S>                                                                                    <C>
REFERENCE DATA

Paragraph 1.1              Subject Referred To                                           1
Paragraph 1.2              Exhibits                                                      4

ARTICLE II - PREMISES AND TERM:

Paragraph 2.1              Premises                                                      4
Paragraph 2.2              Term                                                          6

ARTICLE III - CONSTRUCTION:

Paragraph 3.1              Initial Construction                                          6
Paragraph 3.1.1            Tenant's Work                                                10
Paragraph 3.1.2            Tenant's Construction Work                                   12
Paragraph 3.2              Preparation of Premises for Occupancy                        13
Paragraph 3.2.1            Partial Occupancy and Rent Commencement                      16
Paragraph 3.3              General Provisions Applicable to Construction                16
Paragraph 3.4              Representatives                                              16
Paragraph 3.5              Force Majeure                                                17
Paragraph 3.6              Arbitration by Architects                                    17
Paragraph 3.7              Warranty of Landlord's Work and Tenant's Work                18
</TABLE>

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<TABLE>
<CAPTION>
<S>                                                                                    <C>
ARTICLE IV - RENT:

Paragraph 4.1              Rent                                                         18
Paragraph 4.2              Operating Cost Escalation                                    19
Paragraph 4.3              Payments                                                     23

ARTICLE V - LANDLORD'S COVENANTS:

Paragraph 5.1              Landlord's Covenants during the Term                         24
Paragraph 5.1.1            Building Services                                            24
Paragraph 5.1.2            Additional Building Services                                 24
Paragraph 5.1.3            Repairs                                                      24
Paragraph 5.1.4            Quiet Enjoyment                                              25
Paragraph 5.1.5            Intentionally Deleted                                        25
Paragraph 5.1.6            Landlord's Insurance                                         25
Paragraph 5.1.7            Landlord's Indemnity                                         25
Paragraph 5.1.8            Hazardous Materials                                          26
Paragraph 5.1.9            Tenant's Costs                                               26
Paragraph 5.2              Interruptions                                                27

ARTICLE VI - TENANT'S COVENANTS:

Paragraph 6.1              Tenant's Covenants during the Term                           28
Paragraph 6.1.1            Tenant's Payments                                            28
Paragraph 6.1.2            Repairs and Yielding Up                                      29
Paragraph 6.1.3            Occupancy and Use                                            29
Paragraph 6.1.4            Rules and Regulations                                        29
Paragraph 6.1.5            Compliance with Laws and Safety Appliances                   29
Paragraph 6.1.6            Assignment and Subletting                                    30
Paragraph 6.1.7            Indemnity                                                    33
Paragraph 6.1.8            Tenant's Liability Insurance                                 33
Paragraph 6.1.9            Tenant's Workmen's Compensation Insurance                    33
Paragraph 6.1.10           Landlord's Right of Entry                                    33
Paragraph 6.1.11           Loading                                                      34
Paragraph 6.1.12           Landlord's Costs                                             34
Paragraph 6.1.13           Tenant's Property                                            34
Paragraph 6.1.14           Labor or Materialmen's Liens                                 34
Paragraph 6.1.15           Changes or Additions                                         34
Paragraph 6.1.16           Holdover                                                     36
Paragraph 6.1.17           Hazardous Materials                                          36
Paragraph 6.1.18           Signs                                                        37
Paragraph 6.1.19           Tenant's Authority                                           38
Paragraph 6.1.20           Confidentiality                                              38
</TABLE>

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<TABLE>
<CAPTION>
<S>                                                                                    <C>
ARTICLE VII - CASUALTY AND TAKING:

Paragraph 7.1              Casualty and Taking                                          38
Paragraph 7.2              Reservation of Award                                         41
Paragraph 7.3              Additional Casualty Provisions                               41

ARTICLE VIII - RIGHTS OF MORTGAGEE:

Paragraph 8.1              Priority of Lease                                            42
Paragraph 8.2              Limitation on Mortgagees Liability                           42
Paragraph 8.3              Mortgagee's Election                                         42
Paragraph 8.4              No Prepayment or Modification                                42
Paragraph 8.5              No Release or Termination                                    43
Paragraph 8.6              Continuing Offer                                             43
Paragraph 8.7              Submittal of Financial Statement                             43

ARTICLE IX - DEFAULT:

Paragraph 9.1              Events of Default                                            44
Paragraph 9.2              Tenant's Obligations After Termination                       44

ARTICLE X - MISCELLANEOUS:

Paragraph 10.1             Titles                                                       45
Paragraph 10.2             Notice of Lease                                              45
Paragraph 10.3             Notices from One Party to the Other                          45
Paragraph 10.4             Bind and Inure                                               46
Paragraph 10.5             No Surrender                                                 46
Paragraph 10.6             No Waiver, etc.                                              46
Paragraph 10.7             No Accord and Satisfaction                                   46
Paragraph 10.8             Cumulative Remedies                                          47
Paragraph 10.9             Partial Invalidity                                           47
Paragraph 10.10            Right to Cure                                                47
Paragraph 10.11            Estoppel Certificate                                         48
Paragraph 10.12            Waiver of Subrogation                                        48
Paragraph 10.13            Brokerage                                                    49
Paragraph 10.14            Parking/Traffic Personnel                                    49
Paragraph 10.15            Access                                                       50
Paragraph 10.16            Entire Agreement                                             50
Paragraph 10.17            Governing Law                                                50
Paragraph 10.18            Additional Representations                                   50
Paragraph 10.19            Rooftop Communication Equipment                              50
</TABLE>

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                     Date of Lease Execution: March 31, 2000

                                 REFERENCE DATA

1.1  SUBJECTS REFERRED TO:

     Each reference in this Lease to any of the following subjects shall
     incorporate the data stated for that subject in this Section 1.1.

     LANDLORD:                     Arthur J. Gutierrez and John A. Cataldo,
                                   Class A Trustees, and Howard Stock and Marc
                                   D. Levy, Class B Trustees, all as Trustees of
                                   Michelson Farm-Westford Technology Park
                                   Trust, under Declaration of Trust dated
                                   October 1, 1984, recorded with the Middlesex
                                   North District Registry of Deeds in Book
                                   2863, Page 235

     MANAGING AGENT:               The Gutierrez Company

     LANDLORD'S AND MANAGING       Burlington Office Park
     AGENT'S ADDRESS:              One Wall Street
                                   Burlington, Massachusetts 01803

     LANDLORD'S REPRESENTATIVE:    John A. Cataldo

     LANDLORD'S CONSTRUCTION       Arturo J. Gutierrez, John A. Cataldo
     REPRESENTATIVES:              or P. Agustin Rios

     TENANT:                       Unisphere Solutions, Inc.

     TENANT'S ADDRESS              Prior to Term Commencement Date:
     (FOR NOTICE & BILLING):       Unisphere Solutions, Inc.
                                   5 Carlisle Road
                                   Westford, MA  01886

                                   After Term Commencement Date:
                                   Unisphere Solutions, Inc.
                                   11 Technology Park Drive
                                   Westford, Massachusetts 01886

     TENANT'S REPRESENTATIVE(S):   Robert T. Curtin

     TENANT'S CONSTRUCTION
     REPRESENTATIVE(S):            Andrew Currie

<PAGE>   5

     BUILDING:                     Three (3) story building consisting of
                                   150,000 rentable square feet constructed upon
                                   the land described on Exhibit A attached
                                   hereto (the "Lot") in accordance with the
                                   final Landlord's Plans and Tenant's Plans (as
                                   defined in Article III hereof, and any
                                   replacements thereof) and any alterations and
                                   additions thereto, including the Tenant's
                                   Work (as hereinafter defined), and including
                                   any expansion pursuant to Exhibit R. The
                                   legal description of the Lot is attached
                                   hereto as Exhibit A-1.

     RENTABLE FLOOR AREA OF        150,000 gross square feet, as further
     TENANT'S SPACE:               described in Exhibit A

     TOTAL RENTABLE FLOOR AREA     150,000 gross square feet, as may be
     OF THE BUILDING:              expanded pursuant to Exhibit R

     SCHEDULED TENANT'S DESIGN     July 15, 2000, subject to the
     COMPLETION DATE:              provisions of Section 3.1

     SCHEDULED TERM                January 31, 2001
     COMMENCEMENT DATE:

     OUTSIDE DELIVERY DATE:        Per Section 3.2

     TERM EXPIRATION DATE:         Ten (10) years following the Term
                                   Commencement Date determined in accordance
                                   with Section 3.2, subject to extension in
                                   accordance with Exhibit F.

     TERM:                         Ten (10) years, subject to extension in
                                   accordance with Exhibit F.

     FIXED RENT:                   Years 1-5: $2,386,080.00/Year;
                                   $198,840.00/Month; ($15.91/RSF)
                                   Years 6-10: $2,828,580.00/Year;
                                   $235,715.00/Month; ($18.86/RSF)
                                   [To Be Adjusted by Section 3.1.1, if
                                   Applicable]

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<PAGE>   6

     ANNUAL ESTIMATED OPERATING
     COSTS: (Including Real Estate
     Taxes)                        $638,580.00/Year; $53,215.00/Month;
                                   ($4.26/RSF)

     ESTIMATED COST OF ELECTRICAL
     SERVICE TO TENANT'S SPACE
     [Excluded from Fixed Rent]:   See Exhibit D, Paragraph VII

     FIRST FISCAL YEAR FOR TENANT'S
     PAYING OPERATING COSTS        December 31, first occurring twelve (12)
     ESCALATION YEAR ENDING:       months after the Term Commencement Date.

     SECURITY DEPOSIT:             Not Applicable

     GUARANTOR:                    Not Applicable

     PERMITTED USES:               General office, light industrial research and
                                   development, laboratory and such other uses
                                   that are ancillary and accessory thereto.

     REAL ESTATE BROKERS:          Cushman & Wakefield of Massachusetts, Inc.
                                   and CB Richard Ellis

     PUBLIC LIABILITY INSURANCE:
     BODILY INJURY AND PROPERTY DAMAGE:

                                   Each Occurrence:  $1,000,000.00
                                   Aggregate:        $2,000,000.00

     SPECIAL PROVISIONS:           Parking:                   Per Section 10.14
                                   Option to Extend:          Per Exhibit F
                                   Allowances:                Per Exhibit M
                                   Guaranty of Completion:    Per Exhibit O
                                   Market Rent:               Per Exhibit P
                                   Expansion Option:          Per Exhibit R
                                   Right of First Offer       Per Exhibit U

                                       3
<PAGE>   7

1.2  EXHIBITS

     The Exhibits listed below in this Section are incorporated in this Lease by
     reference and are to be construed as part of this Lease:

     EXHIBIT A      Plans Showing Tenant's Space, the Lot and the Park
                    (including the Building Parking Area and Common Areas)
     EXHIBIT A-1    Legal Description of the Lot
     EXHIBIT B-1    Preliminary Base Building Plans
     EXHIBIT B-2    Base Building Outline Specifications
     EXHIBIT C-1    Form of Certificate of Substantial Completion
     EXHIBIT C-2    Form of Certificate of Final Completion
     EXHIBIT D      Landlord's Services
     EXHIBIT E      Rules and Regulations
     EXHIBIT F      Option to Extend
     EXHIBIT G      Tenant Estoppel Certificate
     EXHIBIT H      Intentionally Deleted
     EXHIBIT I      Park Covenants
     EXHIBIT J      Subordination, Non-Disturbance and Attornment Agreement
     EXHIBIT K      Form of Work Change Order
     EXHIBIT L      Definition of Cost of the Work
     EXHIBIT M      Allowances
     EXHIBIT N      Proposed Expanded Building Footprint and Site Plan
     EXHIBIT O      Guaranty of Completion
     EXHIBIT P      Definition of Market Rent
     EXHIBIT Q      List of Existing Exclusives and Exclusions
     EXHIBIT R      Expansion Option
     EXHIBIT S      Schedule
     EXHIBIT T      Form of Notice of Lease
     EXHIBIT U      Right of First Offer

                               ARTICLE II
                            PREMISES AND TERM

2.1  PREMISES

     Subject to and with the benefit of the provisions of this Lease, Landlord
hereby leases to Tenant and Tenant leases from Landlord, the Rentable Floor Area
of Tenant's Space in the Building (hereinafter, the "Tenant's Space") all as
more particularly shown on Exhibit A attached hereto and made a part hereof, as
the same may be expanded pursuant to Exhibit R, together with the appurtenances
described below and in Section 10.14 of this Lease. Tenant's Space as the same
may be expanded pursuant to Exhibit R, with such appurtenances, is hereinafter
collectively referred to as "the Premises".

                                       4
<PAGE>   8

     Tenant shall have, as appurtenant to the Premises, the right to use the
areas shown on the Plan attached as Part of hereto as Exhibit A as "Building
Parking Area", all subject to and as further provided in Section 10.14 hereof
and the Landlord's reserved expansion rights set forth in Exhibit R.

     Tenant shall also have, as appurtenant to the Premises, the right to use in
common with others entitled thereto, subject to reasonable rules of general
applicability to tenants and owners of other lots in the park, commonly known
and referred to as the Michelson Farm-Westford Technology Park and shown on the
Plan of the Park attached hereto as part of Exhibit A (the "Park") from time to
time made by Landlord in accordance with Section 6.1.4 of which Tenant is given
written notice: (a) the common areas now or hereafter located at the Park (the
"Common Areas"), including, without limitation, the Common Areas shown on the
Plan of the Park attached hereto as part of Exhibit A, as such Common Areas may
be amended or modified by Landlord from time to time during the Term hereof (b)
all rights to access, all service areas, drainage of surface water runoff,
including, without limitation, storm drainage systems and detention areas, (c)
all grades, driveways, roadways, sidewalks and footways, lighting systems and
traffic flow patterns, (d) all parking areas designated as common or visitors
parking areas for use of the entire Park, if any, (e) all other rights
appurtenant to the Lot and the Building, (f) all means of access to and from the
Building to the Common Areas, including, without limitation, all sidewalks,
roads, driveways and the like, and (g) all utility lines, electricity, water and
sewage disposal.

     The Landlord and the Tenant acknowledge and agree that as a condition of
the Tenant's obligations under the Lease, the Tenant shall require a leasehold
title insurance policy insuring the Tenant's leasehold interest in the Premises.
Inasmuch as the lot plans, easements and related matters are being finalized
coterminously with the execution of the Lease, the Landlord covenants with the
Tenant that it shall cooperate with the Tenant during the construction of the
Premises to finalize a leasehold title insurance policy in form and content
reasonably acceptable to the Tenant. A loan policy will be generated by the
Landlord in connection with the construction financing to be secured by Landlord
and the Tenant's leasehold title policy shall be generated simultaneously
therewith. The cost of the Tenant's leasehold title insurance policy shall be
the sole responsibility of the Tenant.

The Tenant's leasehold title insurance policy shall insure Tenant's right of
access to the Premises and all easements required for drainage, utilities and
other matters necessary for the Tenant's operations in the Premises. It shall
also provide that the improvements to be located on the Lot, including without
limitation the parking, shall not interfere with, encroach upon, be prohibited
by or cause a violation of any easements which encumber the Lot.

                                       5
<PAGE>   9

2.2  TERM

     To have and to hold for a period (the "Term") commencing on the Term
Commencement Date determined in accordance with Section 3.2 (which said date is
at times being hereafter referred to as the "Commencement Date") and continuing
until the Term Expiration Date, unless sooner terminated as provided in Sections
3.2 or 7.1 or in Article IX, or unless extended pursuant to Exhibit F.

                                   ARTICLE III
                                  CONSTRUCTION

3.1  INITIAL CONSTRUCTION

     Landlord shall fully construct the base Building in accordance with the
preliminary base building plans, including, without limitation, floor plans,
elevations and site plan(s) (collectively, the "PBBP") and Base Building Outline
Specifications attached hereto as Exhibits B-1 and B-2, respectively (all of
such work being collectively referred to as the "Landlord's Work"). In the event
of differences between the PBBP or the Landlord's Plans (as hereinafter defined)
and the Base Building Outline Specifications, the Base Building Outline
Specifications shall govern and control until the Landlord's Plans (as
hereinafter defined) are prepared.

     A complete set of final base Building plans and construction drawings and
specifications, such drawings and specifications to include a detail schedule of
core base Building finish items such as, but not limited to, carpets, doors,
hardware, ceiling grids/tiles, lavatory fixtures, light fixtures, window blinds,
lobby finishes and paint/wall coverings (collectively, the "Landlord's Plans")
shall be prepared by Landlord, at its sole cost and expense. Landlord and Tenant
agree to work together with Landlord's architect, Symmes Maini and McKee
Associates, Inc. in order to achieve a design that meets the standard set forth
below. Furthermore, Landlord agrees to use good faith and diligent efforts to
deliver the Landlord's Plans to Tenant on or before May 1, 2000. Upon receipt,
Tenant shall have seven (7) business days to comment upon the Landlord's Plans.
Landlord and Tenant shall use reasonable efforts to reach agreement on the
Landlord's Plans as soon thereafter as possible. In reaching agreement, Landlord
and Tenant shall each approve portions of the Landlord's Plans that are in
acceptable form and shall note their respective objections to the portions that
are unacceptable to each of them so as to enable Landlord to continue
construction and order materials in a timely manner. In the event that
Landlord's Plans conform with the PBBP, but Tenant does not approve the
Landlord's Plans within seven (7) business days of receipt thereof from
Landlord, then the Outside Delivery Date (as hereinafter defined) shall be
extended for a number of days equal to the number of Tenant Plan Delay Days, as
such term is hereinafter defined. The number of Tenant Plan Delay Days are
defined as and shall be calculated by determining the actual number of days as
certified by Landlord and its architect that the Term Commencement Date was
delayed by such Tenant's failure to approve the Landlord's Plans within the
required seven (7) business days. Landlord agrees to provide Tenant with written
notice of such determination, such notice to include reasonable detail
describing the cause of the delay and the number of Tenant Plan Delay Days as
certified by Landlord and its architect. If Tenant and Tenant's Architect (as
hereinafter defined)

                                       6
<PAGE>   10

disagree with the existence or calculation of Tenant Plan Delay Days as
determined by Landlord and its architect, then Tenant shall, within seven (7)
business days of receipt of Landlord's notice, notify Landlord of its
disagreement, whereupon the dispute shall be determined pursuant to the
arbitration procedures described in Section 3.6 hereof.

     Landlord and Tenant hereby acknowledge and agree that, except as otherwise
set forth herein, following approval by Landlord and Tenant (which shall be in
writing as hereinafter provided), no amendments, modifications or changes shall
be made to the Landlord's Plans without Tenant's prior written approval in each
instance, which such approval shall not be unreasonably withheld or delayed;
provided, however, no such prior approval of Tenant shall be required if the
proposed amendments, modifications or changes are, in Landlord's reasonable
opinion (i) non-material in nature, (ii) replaced by substantially equivalent or
better items and at all times equal to or better than that of the building
located at 7 Technology Park Drive, Westford, Massachusetts, and (iii) do not
adversely affect the Premises. Without limiting the foregoing, Landlord shall
exercise reasonable efforts to provide Tenant with prior written notice of all
proposed amendments, modifications or changes to the Landlord's Plans.

     A complete set of construction plans and specifications for Tenant's Work
(as hereinafter defined) shall be prepared by Tenant's Architect, as hereinafter
defined (collectively, the "Tenant's Plans"). The Tenant's Plans shall be
furnished to Landlord as herein provided. Landlord and Tenant hereby acknowledge
and agree that Tenant has selected Symmes Maini and McKee Associates, Inc. to be
"Tenant's Architect" for preparation of Tenant's Plans, and the costs of
services of such Tenant's Architect shall be borne solely by Tenant (other than
such portion of the cost to be paid by Landlord pursuant to Exhibit M). Tenant's
Architect (and Tenant's Representatives) shall be actively involved in the
design decisions and shall be allowed reasonable access to the Lot and the
Premises during construction to monitor Landlord's compliance with the terms and
provisions of this Lease. Landlord and Tenant hereby further agree that Tenant
shall be solely responsible for coordinating with Tenant's Architect for the
timely preparation of Tenant's Plans in accordance with the terms and provisions
of this Section 3.1. Attached as Exhibit S is a schedule (the "Schedule")
setting forth the respective dates by which Landlord and Tenant anticipate that
(i) Landlord's Plans shall have been delivered to and approved by Tenant, (ii)
Tenant's Plans shall have been delivered to and approved by Landlord, and (iii)
certain portions of Landlord's Work and Tenant's Work shall be substantially
completed. The parties agree to cooperate with each other and to exercise
reasonable efforts to complete the tasks described in the Schedule by the
respective dates set forth therein, Landlord and Tenant hereby further agreeing
that, unless otherwise expressly set forth herein, failure to meet any of such
dates on the Schedule shall not constitute a default or a delay of any type
hereunder.

     Tenant shall deliver the Tenant's Plans to the Landlord by not later than
the Scheduled Tenant's Design Completion Date, provided, however, that (i)
Tenant furnishes to Landlord by not later than April 14, 2000 all information
relating to changes in the structural steel (i.e. rooftop equipment, floor and
roof openings, and other equipment exceeding 100 psf live load), and (ii) Tenant
furnishes to Landlord by not later than May 1, 2000 all information relating to
any added doors at the first floor exterior wall and relating to proposed
changes to or additions to the

                                       7
<PAGE>   11

elevators and all information relating to any proposed changes or additions to
the base building rooftop HVAC equipment and to the electrical service and
switchgear. Tenant shall permit Landlord to review and provide input during the
preparation of Tenant's Plans. Upon receipt, Landlord shall have five (5)
business days to comment upon the Tenant's Plans. Landlord and Tenant shall use
reasonable efforts to reach agreement on the Tenant's Plans within ten (10) days
of Tenant's receipt of Landlord's comments thereto. In reaching such agreement,
Landlord and Tenant shall each approve portions of Tenant's Plans that are
acceptable and shall note their respective objections to the portions that are
unacceptable to each of them so as to enable Landlord to continue construction
and order materials in a timely manner. In connection with Landlord's review of
the Tenant's Plans, or if Tenant fails to deliver Tenant's Plans (or any
modifications thereto) by the date set forth above, Landlord may require by
prompt written notice to Tenant (i) modifications in Tenant's Plans (i.e. if
Tenant's Plans are not compatible with Landlord's Plans), and/or (ii) an
adjustment in the Outside Delivery Date (such adjustment to be determined by
Landlord in its reasonable judgment). Landlord's notice to Tenant shall include
reasonable detail describing the cause of the adjustment and/or the extent of
the incompatibility with reasonable specificity. Any such extension in time,
whether mutually agreed to by Landlord and Tenant or determined by their
respective architects in the event of dispute pursuant to Section 3.6, shall
result in Tenant's Plan Delay Days as hereinbefore determined. In addition,
Landlord will not approve Tenant's Plans which involve any construction,
alterations or additions requiring unusual expense to readapt the Premises to
normal office use on the Term Expiration Date, unless Tenant first gives
assurances acceptable to Landlord that such readaptation shall be made prior to
such termination without expense to Landlord. Notwithstanding the preceding
sentence, Landlord hereby acknowledges and agrees that such cafeterias,
laboratories and other initial Tenant improvements described in Landlord's Plans
or Tenant's Plans shall not require removal by Tenant at the expiration of the
Term and such initial Tenant improvements shall be allowed to remain without
additional cost to Tenant. All revisions and modifications to the Tenant's Plans
shall be made promptly by Tenant and revised sets of Tenant's Plans shall be
forthwith furnished to Landlord upon Tenant's receipt thereof, Landlord hereby
agreeing to inform Tenant during the plan approval process and, in any event,
prior to the installation thereof, of any such items that may require unusual
expense to readapt the Premises as aforesaid. All revisions and modifications to
the Tenant's Plans shall be made promptly by Tenant and revised sets of Tenant's
Plans shall be forthwith furnished to Landlord upon Tenant's receipt thereof.
Landlord and Tenant hereby further agree to acknowledge in writing when final
approval by Landlord and Tenant of Tenant's Plans (and Landlord's Plans) has
occurred. No changes or modifications to Tenant's Plans or Tenant's Work being
constructed by Landlord pursuant thereto shall be made without Tenant's consent,
such consent not to be unreasonably withheld or delayed by Tenant.

     Landlord shall have fifteen (15) days after final approval of Tenant's
Plans and Landlord's receipt of final and complete sets of approved Tenant's
Plans, which such final approval has been acknowledged in writing by Landlord
and Tenant as aforesaid, to price the cost of Tenant's Work (as hereinafter
defined) in accordance with the last paragraph of Section 3.1.1.

                                       8
<PAGE>   12

     Landlord and Tenant shall cooperate during the above time periods so that
each party makes the other aware of their progress with respect to the foregoing
plans, selections and pricing, as well as timing, availability or cost
constraints of Tenant's selections or specifications and proposed alternates.

     Landlord shall cause the Premises to be completed in accordance with
Landlord's Plans and Tenant's Plans, all of such work to be performed by
Landlord's general contractor, Gutierrez Construction Co., Inc. After final
approval of Landlord's Plans and Tenant's Plans by Landlord and Tenant, the
Tenant may request changes to Landlord's Work or Tenant's Work (as applicable)
by altering, adding to, or deducting from Landlord's Work or Tenant's Work (as
applicable) as set forth in the agreed form of Landlord's Plans or Tenant's
Plans, as applicable (each such requested change is referred to herein as a
"Change Order"). A Change Order requested by Tenant in Landlord's Work (or in
Tenant's Work as such term is defined in Section 3.1.1 hereof) which affects
Landlord's Work may also necessitate an adjustment in the Outside Delivery Date
(as defined in Section 3.2 hereof) and may result in Tenant Alteration Delay
Days (as hereinafter defined), in accordance with and subject to the terms and
conditions set forth below. Landlord shall notify Tenant in writing if such
requested Change Order shall result in Tenant Alteration Delay Days, and
therefore an adjustment in the Outside Delivery Date. In addition, Landlord
agrees to provide Tenant, upon Tenant's request, with sufficient itemization and
back-up documentation to facilitate analysis and to confirm the cost of any such
changes in the Landlord's Work or the Tenant's Work initiated by Tenant. Tenant
shall pay to Landlord an amount equal to the actual cost (as defined in Section
3.1.1 hereof) of Landlord's Work, including the costs of any such changes
initiated by Tenant, less any appropriate credits for any Landlord's Work
deleted, (hereinafter, the "Net Additional Cost of Landlord's Work"). The Net
Additional Cost of Landlord's Work shall be due and payable to Landlord in the
manner provided for in Section 3.1.1 hereof.

     In the event that Tenant requests a Change Order which would, due to
materials or equipment having long delivery times or due to resulting sequencing
delays, and notwithstanding Landlord's diligent efforts, result in a delay in
the Term Commencement Date, then Tenant shall be deemed to have agreed that it
will pay Fixed Rent (as hereinafter provided in Section 4.1) and additional rent
hereunder for a number of days equal to the actual number of days (the "Tenant
Alteration Delay Days") as certified by Landlord and its architect, and agreed
to by Tenant and Tenant's Architect as hereinafter provided, by which the Term
Commencement Date would be delayed by such alterations or additions, giving due
consideration to Landlord's obligation to use diligent efforts to accelerate
construction to make up for lost time due to delays. Landlord agrees to promptly
provide Tenant with written notice of such determination, such notice to include
reasonable detail describing the cause of the delay and the number of Tenant
Alteration Delay Days as certified by Landlord and its architect. Should Tenant
and Tenant's Architect disagree with the calculation of Tenant Alteration Delay
Days as hereinabove determined, then such disagreement shall be resolved
pursuant to the provisions of Section 3.6 hereof.

     All Tenant improvements, changes and additions shall be part of the
Premises (and shall remain therein at the end of the Term), except for Tenant's
business fixtures, equipment and personal property (which such personal property
shall include, without limitation, demountable

                                       9
<PAGE>   13

partitions, equipment and telephone or computer systems), all of which fixtures,
equipment and personal property shall remain the property of the Tenant and
shall be removed at the expiration of the Term; and such other items shall be
removed or left as the Landlord and Tenant agree in writing at the time of
Landlord's approval of the plans and specifications therefor. Tenant agrees to
repair, at its sole cost and expense, any damage to the Premises caused by any
such removal by Tenant in accordance with this paragraph. As aforesaid,
notwithstanding the foregoing provisions on this paragraph, Tenant shall not be
required to remove cafeterias, laboratories or other initial Tenant improvements
described in Landlord's Plans or Tenant's Plans upon expiration of the Term and
such initial Tenant improvements shall be allowed to remain without additional
cost to Tenant.

3.1.1 TENANT'S WORK.

     Landlord and Tenant agree that Gutierrez Construction Co., Inc. will
construct the tenant improvements set forth on the Tenant's Plans (hereinafter
"Tenant's Work") with respect to the Premises at cost (as hereinafter defined),
plus an amount for general conditions of seven percent (7%) (not to exceed
$420,000.00) and a Landlord's contractor's fee of six percent (6%) of such
aggregate cost, less an amount equal to the allowance set forth on Exhibit M
attached hereto and made a part hereof. In order to provide for payment by
Tenant of the cost of Tenant's Work, the Net Additional Cost of Landlord's Work,
and any additional costs due to Change Orders provided for hereunder, less said
allowance, Tenant expressly covenants with Landlord that Tenant agrees to
deposit into an interest-bearing account to be established and maintained by
Landlord's mortgagee (or such other escrow agent mutually agreed upon by the
parties), (i) by April 1, 2000, $3,000,000.00 (i.e. forty-three percent (43%) of
the Total Estimated Cost set forth below), and (ii) by October 1, 2000, an
additional $4,000,000.00 (i.e. fifty-seven percent (57%) of the Total Estimated
Cost as set forth below). Tenant's deposits into escrow shall be released by
Landlord's construction mortgagee, as escrow agent, to Landlord, or its
contractors, as the case may be, upon Substantial Completion of Landlord's Work
and Tenant's Work, as provided in Section 3.2 hereof. Tenant shall be
responsible for payment of escrow fees, if any, incurred by Landlord or Tenant
in connection with such escrow account. In addition, Tenant shall be responsible
for interest costs and one-half percent (1/2 %) commitment fee incurred by
Landlord in connection with its financing of the cost of Tenant's Work and
Change Orders, as applicable. Any and all interest earned on the escrowed funds
shall be payable to Tenant at such time as the escrow is released by Landlord's
mortgagee, or such other mutually agreed upon escrow agent as aforesaid. It is
acknowledged and agreed by Landlord and Tenant that Landlord's mortgagee shall
have no right to set off such escrow account against any of Landlord's
obligations with its mortgagee. In the event that this Lease is terminated by
Tenant pursuant to the provisions of Section 3.2, Landlord's mortgagee shall
release all amounts in the escrow account (including interest) to Tenant.

     The total estimated cost to complete the Tenant's Work under this Lease is
seven million dollars ($7,000,000.00) or forty dollars ($46.67) per square foot
(hereinafter, the "Total Estimated Cost"). To the extent that the actual cost of
the Tenant's Work, Net Additional Cost of Landlord's Work and/or Change Orders,
as determined by this Article, is greater than the Total Estimated Cost,
Landlord shall provide Tenant with written notice of such fact together with

                                       10
<PAGE>   14

reasonable supporting information. In such event Landlord shall provide Tenant
with monthly construction requisitions for the construction of the portion of
the Tenant's Work, Net Additional Cost of Landlord's Work and/or Change Orders
in excess of the Total Estimated Cost, and Tenant agrees to deposit into said
escrow account monthly the total amount of any such monthly requisitions based
on a percentage of completion basis within five (5) business days of receipt
thereof, and any such additional deposits made by Tenant shall be released to
Landlord at the time and in the manner as the two (2) deposits noted above.

     Notwithstanding the foregoing, it is hereby acknowledged and agreed that
Landlord shall, at Tenant's option, use good faith efforts to obtain third party
permanent non-recourse financing for the financing of the foregoing costs due
from Tenant hereunder, which shall be subject to the financability of Tenant. If
such financing is obtained, Landlord agrees to notify Tenant and to amortize the
amount so financed into the Rent due hereunder on such terms to be mutually
agreed to by the parties, each acting reasonably and in good faith. Landlord and
Tenant hereby further agree (i) to amend this Lease so as to reflect any amount
so financed by Landlord hereunder and (ii) the amount so deposited into escrow
by Tenant hereunder shall be offset proportionately by the amount financed by
Landlord as aforesaid.

     Landlord and Tenant hereby further acknowledge and agree to enter into a
formal escrow agreement with Landlord's mortgagee or such other escrow agent as
aforesaid, to implement the foregoing arrangements prior to April 1, 2000, such
date being the first date upon which Tenant is required to deposit funds into
escrow. A proposed draft of such escrow agreement has been forwarded to Tenant
for review and approval.

     Each requisition shall include copies of all subcontractor's and supplier's
applications for payment and satisfactory evidence of payment of all previous
invoices submitted by subcontractors and suppliers. In addition, Landlord's
architect shall certify that the subject work specified in each of such monthly
requisitions has been substantially completed, and a copy of such certification
shall accompany each requisition furnished to Tenant hereunder. In no event
shall any of such costs due and payable hereunder remain unpaid by Tenant as of
the Term Commencement Date. Tenant and Tenant's Architect shall have the
opportunity to inspect the subject work and to confirm the foregoing
certification by Landlord's architect, and any disputes following such
inspection(s) shall be determined pursuant to Section 3.6 hereof.

     For purposes hereof, Landlord and Tenant further agree that the
certification of cost by Gutierrez Construction Co., Inc. shall be based on the
definition of cost as more particularly set forth in Exhibit L hereto. Any
changes to the Tenant's Plans after the approval of the Tenant's Plans (and any
changes to Landlord's Plans after the approval thereof as set forth in Section
3.1 above) shall be in accordance with the form of Work Change Order attached
hereto as Exhibit K.

     If Tenant informs Landlord in writing of its election to require that
Landlord bid out the major contracts in the pricing of the cost of Tenant's Work
(specifically excluding Landlord's Work hereunder), Landlord agrees to obtain
three (3) qualified bids from subcontractors selected from a master list of
subcontractors mutually prepared and agreed upon by Landlord and Tenant prior to
the soliciting of bids for any item of Tenant's Work exceeding twenty-five
thousand

                                       11
<PAGE>   15

dollars ($25,000.00). The subcontractor selected for the performance of the work
shall be, subject to Tenant's right to select the final bidder as hereinafter
provided, the subcontractor with the lowest bid price; provided, however, that
if Landlord, in its reasonable judgment, determines that due to changed
conditions (such as increased work commitments on the part of the respective
subcontractor, or other pertinent factors) the selection of such low bidder
could result in Subcontractor Delay Days (as hereinafter defined), then Landlord
shall provide written notice (a "Landlord's Subcontractor Notice") thereof to
Tenant, which notice shall identify the low bidder and next lowest bidder and
indicate the number of Subcontractor Delay Day(s) that would result from
selection of the low bidder (giving due consideration of Landlord's obligations
to use diligent efforts to accelerate construction to make up for lost time to
delays). Tenant shall have four (4) business days upon receipt of such
Landlord's Subcontractor Notice to notify Landlord that either (i) Landlord
should proceed with the original low bidder (in which event the Outside Delivery
Date shall be extended for the number of days (the "Subcontractor Delay Day(s)")
equal to the number of Subcontractor Delay Days indicated in Landlord's
Subcontractor Notice), or (ii) Landlord's selection of the next lowest bidder is
acceptable to Tenant (in which event the Outside Delivery Date shall not be
extended), or (iii) Landlord shall select the third bidder if Tenant, in its
reasonable discretion, determines that the third bidder should be the one
selected for performance of the work (in which event Landlord shall notify
Tenant if such selection shall result in Subcontractor Delay Days and if so, the
number of delay days, whereupon Tenant shall have an additional four (4)
business days to advise Landlord as to its selection). If Tenant so selects such
third bidder, then Landlord shall proceed with such bidder and the Outside
Delivery Date shall be extended for the number of Subcontractor Delay Days
indicated in Landlord's notice. Failure by Tenant to respond within either of
said four (4) day periods shall be deemed to constitute acceptance by Tenant of
Landlord's selection of the next lowest bidder. Landlord agrees to use
reasonable efforts to notify Tenant simultaneously or forthwith upon Tenant's
notification to Landlord as to its election set forth in (i), (ii) or (iii)
above, if Landlord has knowledge or a reasonable basis to believe that a
Subcontractor Delay Day(s) will likely result due to Landlord's notification
requirements hereunder, regardless of whether or not Tenant elects to proceed
with the original lowest bidder or not. In addition, in the event that Landlord
and Tenant are unable to agree on the cost of any portion of said work, any
disagreement shall be resolved pursuant to the provisions of Section 3.6 hereof.

     Upon commencement of the Tenant's Work, Landlord and Tenant hereby further
agree, each acting reasonably and in good faith, to attend and participate in
weekly construction meetings with Landlord's general contractor's construction
manager(s) during such construction process.

3.1.2 TENANT'S CONSTRUCTION WORK.

     Tenant agrees that any construction included in Tenant's Plans which Tenant
specifies to be done by itself or its contractors (hereinafter referred to as
"Tenant's Construction Work"), which shall include, for example, Tenant's
installation of furnishings, lab equipment, IT/MIS, security and later changes
or additions, shall be completed by and coordinated with any work being
performed by Landlord in such manner as to maintain harmonious labor relations
and not materially damage the Premises or Lot or materially interfere with the
operation of the Building

                                       12
<PAGE>   16

or with any of Landlord's construction work hereunder, including but not limited
to the construction of the Landlord's Work and Tenant's Work. Tenant (including
its contractors, agents or employees) shall have access to the Premises and may
perform Tenant's Construction Work prior to the Scheduled Term Commencement Date
and prior to the commencement of the Term so as to prepare the Premises for
occupancy by Tenant ("Pre-Occupancy"), provided that (i) Tenant's contractors,
agents or employees work in a harmonious labor relationship with Landlord's
general contractor, (ii) reasonable prior written notice is given to Landlord's
general contractor specifying the work to be done, and (iii) no work, as
reasonably determined by Landlord, shall be done or fixtures or equipment
installed by Tenant in such manner as to materially interfere with the
completion of Landlord's Work and the Tenant's Work being done by or for
Landlord on the Premises. During the period of preoccupancy of the Premises by
Tenant in connection with Tenant's Construction Work prior to the commencement
of the Term, no Fixed Rent or additional rent or other charges shall accrue or
be payable, but otherwise such preoccupancy shall be subject to all the terms,
covenants and conditions contained in this Lease.

3.2  PREPARATION OF PREMISES FOR OCCUPANCY.

     Landlord shall perform the construction work set forth in the Landlord's
Plans and the Tenant's Plans, and, therefore, Landlord agrees to use diligent
efforts to have the Premises ready for occupancy on the Scheduled Term
Commencement Date.

     Landlord and Tenant agree that time is of the essence, and Landlord agrees
to use diligent efforts to accelerate construction to make up for time lost due
to any delay. Unless sooner terminated by Tenant pursuant to the provisions of
Section 3.2, the Term of this Lease shall commence on the date the Premises are
deemed ready for occupancy as set forth below (the "Term Commencement Date").

     The Premises shall be deemed "ready for occupancy" on the earlier of:

     (a)  the date on which Tenant occupies all or any portion of the Premises
for the Permitted Uses (except this shall not include periods of Pre-Occupancy
by Tenant as set forth in Section 3.1.2); or

     (b)  (1) the date on which the construction of all of the Landlord's Work
and the Tenant's Work is Substantially Completed, as defined below, and (2)
Landlord has delivered to Tenant copies of all permits and approvals (the
"Permits") required to be obtained from any governmental agency either in
connection with the (i) construction of the Building or the Park, or any part
thereof, or (ii) prior to occupancy of the Premises by Tenant, including,
without limitation, a permanent certificate of occupancy from the Town of
Westford or a temporary certificate of occupancy from the Town of Westford which
allows Tenant to use and occupy the Premises, including in all cases use of the
elevator(s), and which temporary certificate of occupancy is not conditional on
the performance of any work other than the Punch List Work as defined below,
except that such Permits shall not be required as a condition of Substantial
Completion if Landlord is unable to secure the same due solely to Tenant's
failure to complete Tenant's Construction Work as specified in Section 3.1.2
above (which such date, subject to

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<PAGE>   17

additional terms and provisions of this Section 3.2, shall hereinafter be
referred to as the date of "Substantial Completion" or which such work shall
hereinafter be referred to as "Substantially Completed"). In any event,
notwithstanding the achievement of Substantial Completion, all Punch List Work
shall be completed by no later than thirty (30) days after the date of
Substantial Completion, except as hereinafter provided.

     An AIA Certificate of Substantial Completion by the Landlord's architect
and approved by Tenant's Architect (which such Certificate shall be in the form
attached hereto as Exhibit C-1), shall evidence the Landlord's determination
that it has performed all such obligations, except for completing the
landscaping work and completing the final paving course, and minor items stated
in such Certificate to be incomplete or not in conformity with such
requirements, or will not materially interfere with Tenant's use or occupancy of
the Premises and all of which work shall be identified and specified in the
Certificate of Substantial Completion (collectively such landscaping work,
finish paving course work and minor items are referred to herein as the "Punch
List Work") shall be promptly completed. Tenant shall have the right within
fifteen (15) days after Tenant's receipt of said Certificate of Substantial
Completion to notify Landlord of its disagreement with said Certificate and to
identify additional items of Punch List Work, all of which shall be completed by
Landlord within thirty (30) days after notice thereof from Tenant.

     If weather materially and adversely interferes with Landlord's ability to
finish the final course of paving and outside work or such other Punch List
Work, which such work does not materially interfere with Tenant's occupancy, and
the operation of Tenant's business therein, said work can be completed by
Landlord reasonably thereafter, so long as such delay does not and will not
interfere with or prevent Landlord from obtaining a certificate of occupancy
upon completion of all other work herein described.

     Notwithstanding the foregoing, in the event that the Punch List Work is not
completed by Landlord on or before such date which is six (6) months following
the date of Substantial Completion, then Tenant shall have the right, but not
the obligation, to complete the Punch List Work and charge the Landlord the
difference, if any, between the costs reasonably incurred by Tenant in
completing the same, provided that at least thirty (30) days prior written
notice has been provided to Landlord, its mortgagee (of whose address Tenant has
been given written notice) and The Gutierrez Company (as guarantor under the
Guaranty of Completion to be furnished to Tenant upon execution of this Lease,
such guaranty to be in the form attached hereto as Exhibit O) and Landlord shall
have not cured (or commenced to cure and is not prosecuting curing of the same
to completion with due diligence) the same. Landlord agrees to reimburse Tenant
pursuant to the provisions of 10.10(b) hereof and shall be entitled to such
offset rights as set forth therein.

     After Landlord has completed all Landlord's Work and Tenant's Work,
including all Punch List Work, Landlord's architect shall forward to Tenant its
Certificate of Final Completion, such Certificate to be in the form attached
hereto as Exhibit C-2. In addition, promptly after completion of all such work,
including all Tenant's Construction Work by Tenant, Landlord shall forward to
Tenant a final certificate of occupancy from the Town of Westford.

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<PAGE>   18

     The phrase "Tenant's Delay" shall mean the aggregate number of days
(excluding any days of delay caused by or resulting from Force Majeure) equal to
the actual number of days that, notwithstanding its diligent and good faith
efforts to complete construction by the Scheduled Term Commencement Date, the
Landlord is delayed in completing its construction by the Scheduled Term
Commencement Date due to (i) the failure of the Tenant to deliver the Tenant's
Plans (or modifications thereto) to Landlord on the dates established pursuant
to Section 3.1 hereof, or (ii) a delay caused by Tenant performing the Tenant's
Construction Work pursuant to Section 3.1.2 hereof, or (iii) the number of
Subcontractor Delay Days pursuant to Section 3.1.1 hereof, or (iv) a delay or
stoppage requested in writing by Tenant, or (v) the number of Tenant Alteration
Delay Days resulting from Change Orders requested by Tenant pursuant to Section
3.1 hereof, or (vi) the number of Tenant Plan Delay Day(s) pursuant to Section
3.1 hereof, then the Term Commencement Date shall be deemed to have occurred on
the date, as certified by Landlord and its architect, and agreed upon by
Tenant's Architect, that Substantial Completion would have occurred had there
not occurred such Tenant's Delay, calculated by determining the number of days
of Tenant's Delay as aforesaid, giving consideration to Landlord's obligation
under the second paragraph of this Section 3.2 to accelerate to make up for time
lost due to any delays. Landlord agrees to promptly provide Tenant with written
notice of such Tenant's Delay promptly after the occurrence of such Tenant's
Delay, such notice to include reasonable detail describing the cause of the
delay as certified by Landlord's architect.

     Notwithstanding the foregoing provisions, if the Premises are not deemed
ready for occupancy on or before the Outside Delivery Date (as defined below)
for whatever reason, Tenant may elect (i) to cancel this Lease at any time
thereafter while the Premises are not deemed ready for occupancy by giving
notice to Landlord of such cancellation which shall be effective ten (10) days
after such notice, unless within such ten (10) day period Landlord delivers the
Premises ready for occupancy as defined herein, in which event such notice of
cancellation shall be rendered null and void and of no further force or effect,
or (ii) to enforce Landlord's covenants to construct the Premises in accordance
with the terms of this Lease. In the event Tenant elects to enforce Landlord's
agreement to construct the Premises in accordance with this Lease, Tenant shall
also have the right to terminate this Lease if Landlord fails to complete the
Premises within the period of time set by any court of competent jurisdiction
for such work to be completed, or within such additional period of time from the
date of Landlord's default as may be mutually agreed to by Landlord and Tenant.
Notwithstanding any provisions of this Lease to the contrary, in the event that
the Premises are not deemed ready for occupancy on or prior to such date which
is ninety (90) days following the Scheduled Term Commencement Date (as such date
may be extended for reasons due to Force Majeure and/or to Tenant's Delay), then
Tenant may elect to receive from Landlord as liquidated damages an abatement of
Fixed Rent, less the Annual Estimated Operating Costs (following commencement of
rental obligations pursuant to Section 4.1) equal to one hundred percent (100%)
of the Fixed Rent, less the Annual Estimated Operating Costs, for each day the
Tenant's Work and Landlord's Work is not Substantially Completed ninety (90)
days beyond the Scheduled Term Commencement Date (as such date may be extended
as aforesaid). The foregoing remedies shall be Tenant's sole and exclusive
remedies for not having the Premises completed on or before the Outside Delivery
Date.

                                       15
<PAGE>   19

     For purposes hereof, the Outside Delivery Date shall be deemed to refer to
that certain date which is sixty (60) days following the Scheduled Term
Commencement Date, as such date may be extended for a period equal to that of
(i) any delays due to Force Majeure as defined in Section 3.5 hereof, (ii) the
number of delay days caused by a Tenant's Delay as hereinbefore determined;
provided, however, that there shall be no extensions for the matters set forth
in clause (i) above (specifically excluding the matters set forth in clause (ii)
above) for more than forty-five (45) days in the aggregate.

3.2.1 PARTIAL OCCUPANCY AND RENT COMMENCEMENT.

     If the entire Premises are not ready for occupancy on the Scheduled Term
Commencement Date, the Tenant may elect, but shall have no obligation to, occupy
any portion or portions of the Premises which are ready for occupancy when, in
Landlord's opinion, it can be done without material interference with remaining
work. In such event, Tenant agrees not to materially interfere with Landlord's
construction of the Premises. In the event Tenant elects to take occupancy of a
portion of the Premises, that portion shall be deemed ready for occupancy as to
said portion on the date of occupancy of such portion and Tenant's obligation to
pay Fixed Rent and additional rent shall commence on said date pro rata based on
the square footage occupied compared to the total square footage in the
Premises. The foregoing provisions of this Section 3.2.1 shall not apply to the
rights of Tenant set forth in Section 3.1.2 hereof.

3.3  GENERAL PROVISIONS APPLICABLE TO CONSTRUCTION

     All construction work required or permitted by this Lease, whether by
Landlord or by Tenant (or their respective subcontractors), shall be done in a
good and workmanlike manner and in compliance with Landlord's Plans and Tenant's
Plans and all applicable laws and all lawful ordinances, regulations and orders
of governmental authority and insurers of the Building. Either party may inspect
the work of the other at reasonable times and shall promptly give notice of
observed defects. Notice of said defects shall be in writing and shall be
rectified by Landlord or Tenant, as the case may be, within thirty (30) days of
the original date of notice. Except as otherwise provided in Section 3.7 hereof,
failure to provide notice hereunder shall not be the basis for any liability or
for injury or damage caused by such defect of or waiver of right to cause any
defect to be corrected.

3.4  REPRESENTATIVES

     Landlord hereby acknowledges and agrees that only the following persons,
Robert T. Curtin, Andrew Currie or Stephen Hassell, or any successors to either
of them holding the same title or any other person delegated the authority from
either of them in writing (hereinafter "Tenant's Construction Representatives")
have the authority to act on Tenant's behalf and represent Tenant's interest
with respect to all matters requiring Tenant's action in this Article. No
consent, authorization or other action by Tenant with respect to matters set
forth in this Article shall bind Tenant unless in writing and signed by one of
the aforementioned persons. Landlord hereby expressly recognizes and agrees that
no other person claiming to act on behalf of Tenant is authorized to do so. If
Landlord complies with any request or direction presented to it by

                                       16
<PAGE>   20

anyone claiming to act on behalf of Tenant who does not have the title and
position mentioned above, such compliance shall be at Landlord's sole risk and
responsibility and shall not in any way alter or diminish the obligations and
requirements created and imposed by this Article, and Tenant shall have the
right to enforce compliance with this Article without suffering any waiver or
abrogation of any of its rights hereunder.

     Tenant hereby acknowledges and agrees that only the following persons,
Arturo J. Gutierrez, John A. Cataldo or P. Agustin Rios or any successors to
either of them holding the same title or any other person delegated the
authority from either of them in writing (hereinafter "Landlord's Construction
Representatives") have the authority to act on Landlord's behalf and represent
Landlord's interests with respect to all matters requiring Landlord's action in
this Article. No consent, authorization or other action by Landlord with respect
to matters set forth in this Article shall bind Landlord unless in writing and
signed by one of the aforementioned persons. Tenant hereby expressly recognizes
and agrees that no other person claiming to act on behalf of Landlord is
authorized to do so. If Tenant complies with any request or direction presented
to it by anyone claiming to act on behalf of Landlord who does not have the
title and position mentioned above, such compliance shall be at Tenant's sole
risk and responsibility and shall not in any way alter or diminish the
obligations and requirements created and imposed by this Article, and Landlord
shall have the right to enforce compliance with this Article without suffering
any waiver or abrogation of any of its rights hereunder.

3.5  FORCE MAJEURE.

     As used in this Article and elsewhere in the Lease, "Force Majeure" shall
mean a time extension equal to that of any delays when the party required to
perform the respective obligation is prevented from doing so, despite the
exercise of reasonable diligence, and such delay is caused by: (i) Acts of God,
(ii) changes in government regulations, (iii) casualty, (iv) strike or other
such labor difficulties, (v) unusual weather conditions, (vi) unusual scarcity
of or inability to obtain supplies, parts or employees to furnish such services,
or (vii) other acts reasonably beyond Landlord's control, but in no event shall
the term include economic or financing difficulties. Landlord shall provide
Tenant with written notice of the occurrence of a Force Majeure event promptly
after the occurrence thereof, and shall comply with its respective obligation(s)
as soon as the cause for the delay has (have) been eliminated. As hereinbefore
provided in Section 3.2, extensions due to Force Majeure shall be limited to
forty-five (45) days in the aggregate.

3.6  ARBITRATION BY ARCHITECTS.

     Whenever there is a disagreement between the parties with respect to
construction by Landlord of Landlord's Work or Tenant's Work, such disagreement
shall be definitively determined by the following procedure: Each of Landlord
and Tenant shall appoint one (1) independent architect (which such architect may
be Landlord's Architect and Tenant's Architect referenced in section 3.1 above),
such two (2) architects will then (within five (5) days of their appointment)
appoint a third independent architect licensed in the Commonwealth of
Massachusetts with not less than ten (10) years experience. Each architect shall
establish within ten (10) days of their appointment the matter in dispute. In
case of any dispute with respect to

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<PAGE>   21

dollar amounts or lengths of time or dates such as the date of Substantial
Completion, the dollar amount or length of time or date shall be the average of
the two closest determinations by the three (3) architects, with the
determination of the architect which was not closest to another architect's
determination excluded from such calculation. In case of any dispute not
involving dollar amounts or lengths of time or dates (i.e. the approval of
plans) the determination by at least two (2) of the three (3) architects shall
be required in order to resolve the matter in dispute. Landlord and Tenant shall
each bear the cost of the architect selected by them respectively and shall
share equally the cost of the third architect. During such arbitration period,
the parties agree to cooperate with one another so as to proceed with
construction and with their respective obligations hereunder in a timely manner.
Each determination under this Section 3.6 shall be binding upon Landlord and
Tenant.

3.7  WARRANTY OF LANDLORD'S WORK AND TENANT'S WORK.

     Notwithstanding the provisions of Section 3.3, Landlord hereby warrants and
guarantees that the Landlord's Work and the Tenant's Work shall be free from
defects in workmanship and materials for a period of one (1) year after the Term
Commencement Date or such later date upon which all such work has been completed
(including Punch List Work). Upon the expiration of said one (1) year period,
Landlord shall assign to Tenant any and all warranties and guarantees with
respect to Landlord's Work and Tenant's Work and, to the extent that any such
warranties and guarantees are not assignable, Landlord agrees to enforce the
same for the benefit of Tenant, at Tenant's sole cost and expense. Tenant shall
not be responsible to pay for any such warranties of less than one (1) year
duration or enforcement by Landlord against its own employees or against
Gutierrez Construction Co., Inc. or against any of its other affiliates
(including their respective employees). Landlord agrees to repair, at its sole
cost and expense any latent defects in Landlord's Work or Tenant's Work promptly
after receipt of notice therefrom from Tenant, provided that such notice from
Tenant is received by Landlord on or before such date which is three (3) years
after the Term Commencement Date or such later date upon which all such work has
been completed (including Punch List Work). In connection therewith, Tenant
shall notify Landlord promptly after it becomes aware of any such latent
defects. Any repairs or replacements or alterations to Landlord's Work or
Tenant's Work after said initial one (1) year period, and any work required
because of latent defects after said three (3) year period, shall be chargeable
to Tenant in accordance with and subject to the provisions of Section 4.2
hereof.

                                   ARTICLE IV
                                      RENT

4.1  RENT

     Tenant agrees to pay, without any offset or reduction, except as expressly
set forth herein, Fixed Rent equal to 1/12th of the annual Fixed Rent set forth
in Section 1.1 in equal installments in advance on the first day of each
calendar month included in the Term; and for any portion of a calendar month
occurring at the beginning or end of the Term, at the rate payable for such
portion in advance. Landlord hereby further agrees to credit the option funds
paid by Tenant

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<PAGE>   22

totaling Four Hundred Eighty Five Thousand ($485,000.00) and interest earned
thereon (commencing on April 1, 2000) against Tenant's rental obligations due
hereunder.

4.2  OPERATING COST ESCALATION

     With respect to the First Fiscal Year for Tenant's Paying Operating Cost
Escalation, or fraction thereof, and any Fiscal Year or fraction thereafter
during the Term, Tenant shall pay to Landlord, as additional rent, Operating
Cost Escalation (as defined below), if any, on or before the thirtieth day
following receipt by Tenant of Landlord's Statement (as defined below). As soon
as practicable after the end of each Fiscal Year ending during the Term and
after Lease termination, Landlord shall render a statement ("Landlord's
Statement") in reasonable detail and according to generally accepted accounting
principles, consistently applied, certified by Landlord, and showing for the
preceding Fiscal Year or fraction thereof, as the case may be, "Landlord's
Operating Costs,"

     EXCLUDING the interest and amortization on mortgages for the Building and
Lot or leasehold interests therein and the cost of special services rendered to
tenants (including Tenant) for which a special charge is made,

     BUT INCLUDING, without limitation: real estate taxes on the Building, the
Lot and the Common Areas of the Park (including without limitation the sewer
treatment plant servicing the Park); installments and interest on assessments
for public betterments or public improvements; expenses of any proceedings for
abatement of taxes and assessments with respect to any Fiscal Year or fraction
of a Fiscal Year; premiums for insurance required to be maintained by Landlord
pursuant to this Lease; compensation and all fringe benefits, workmen's
compensation, insurance premiums and payroll taxes paid by Landlord to, for or
with respect to all persons engaged in the operating, maintaining, or cleaning
of the Building and Lot; steam, water, sewer, electric, gas, telephone, and
other utility charges not billed directly to tenants by Landlord or the utility,
but not including the cost to Landlord of electricity furnished for lighting,
electrical facilities, equipment, machinery, fixtures and appliances used by
Tenant in Tenant's Space (other than Building heating, ventilating and air
conditioning equipment) as set forth in Paragraph VII of Exhibit D; costs of
building and cleaning supplies and equipment (including rental); cost of
maintenance, cleaning and repairs; cost of snow plowing or removal, or both, and
care of landscaping; payments to independent contractors under service contracts
for cleaning, operating, managing, maintaining and repairing the Building and
Lot (which payments may be to affiliates of Landlord provided the same are at
reasonable rates consistent with similar contracts with unaffiliated third
parties); the Building's pro rata share (as hereinafter defined) of the cost of
operating, maintaining and repairing the Common Areas of the Park (such as, but
not limited to, snow plowing, sanding, landscaping, common area and street
lighting, security, management and sewer treatment plant maintenance); and all
other reasonable and necessary expenses paid in connection with the operation,
cleaning, maintenance, and repair of the Building and Lot, or either, and
properly chargeable against income, it being agreed that if Landlord installs a
new or replacement capital item for the purpose of reducing Landlord's Operating
Costs, the costs thereof as reasonably amortized by Landlord over the useful
life in years of the capital item so installed in accordance with generally
accepted accounting principles ("GAAP"), consistently

                                       19
<PAGE>   23

applied, with legal interest on the unamortized amounts, shall be included in
Landlord's Operating Costs. Landlord agrees that all of such services to be
included in Landlord's Operating Costs shall be obtained by Landlord at
commercially reasonable, competitive market rates consistent with the operation
and management of comparable "Class A" office buildings in the suburban Boston
area.

     Notwithstanding anything to the contrary contained herein, in no event
shall Landlord's Operating Costs include (nor shall Tenant have any obligation
to pay any Operating Cost Escalation on account of) the following:

     (a)  Costs, expenses and fees relating to solicitation of, advertising for
          and entering into leases and other occupancy arrangements for space in
          the Park, including but not limited to legal fees, space planners'
          fees, real estate brokers' leasing commissions and advertising
          expenses.

     (b)  Costs of defending any lawsuits with any mortgagee , costs of selling,
          syndicating, financing, mortgaging or hypothecating any of Landlord's
          interest in the Park (or any part thereof), costs of any disputes
          between Landlord and its employees, disputes of Landlord with building
          management, or outside fees paid in connection with disputes with
          other tenants or adjacent property owners.

     (c)  Costs of correcting defects in the Building or the Building equipment
          or replacing defective equipment at any time during the three (3) year
          period described in Section 3.7, subject to the provisions of said
          Section 3.7, and thereafter solely to the extent such costs relate to
          items covered by warranties of manufacturers, suppliers or contractors
          or are otherwise borne by parties other than Landlord and for which
          Landlord receives reimbursement.

     (d)  Costs of installations or improvements of any type paid by or
          constructed for specific tenants or other occupants.

     (e)  Interest, points, other finance charges and principal payments on
          mortgages, and other costs of indebtedness, if any.

     (f)  All amounts which are specifically charged to or otherwise paid by any
          other tenant or other occupant of the Building or the Park, or for
          items or services which Landlord provides selectively to one or more
          tenants (other than Tenant) without reimbursement.

     (g)  Any bad debt loss, rent loss or reserves for bad debts or rent loss.

     (h)  The salary and indirect compensation (including, without limitation,
          all fringe benefits, workmen's compensation, insurance premiums and
          payroll taxes) of any employee above the trade of building manager,
          and the wages and indirect

                                       20
<PAGE>   24

          compensation of any employee to the extent such employee devotes his
          or her time to property other than the Building.

     (i)  Amounts, if any, paid as ground rental by Landlord.

     (j)  Expenses related to landlord-tenant disputes.

     (k)  Management fees in excess of five percent (5%) of gross collected
          rents.

     (l)  Costs related to hazardous material clean-up, remediation and other
          expenses (unless due to Tenant's actions), Landlord and Tenant hereby
          agreeing that in no way shall this exclusion limit or impair Tenant's
          obligations set forth in Section 6.1.17 hereof.

     (m)  Costs of capital improvements, except for such capital improvements
          specifically provided for in this Section 4.2.

     Notwithstanding any language to the contrary contained herein, Landlord's
Operating Costs shall be reduced by reimbursements, credits, discounts,
reductions or other allowances received or receivable by Landlord for items of
cost included in Landlord's Operating Costs (except for reimbursements to
Landlord by tenants under the additional rent provisions of their respective
leases), including any tax refunds realized as a result of any abatement
proceeding or otherwise.

     Tenant shall be responsible to pay its share of Operating Cost Escalation
(as defined below) for the Building based upon the proportion that the Rentable
Floor Area of Tenant's Space bears to the Total Rentable Floor Area of the
Building as the same may be expanded pursuant to the terms of Exhibit R hereto.
Landlord and Tenant hereby acknowledge and agree that the Building's pro rata
share of Park-related costs shall be allocated by Landlord in a commercially
reasonable manner based upon the following: upon the ratio of the square footage
of the Premises to the aggregate square footage of all completed buildings in
the Park, as such buildings are completed from time to time, and, with respect
to sewer treatment plant expenses, connected for service from time to time to
the sewer treatment plant, and upon factors such as usage of a particular tenant
in the Park and/or such other pertinent factors as reasonably determined by
Landlord.

     "Operating Cost Escalation" shall be equal to the difference, if any,
between:

     (a)  the product of Landlord's Operating Costs per rentable square foot as
          indicated in Landlord's Statement times the Rentable Floor Area of
          Tenant's Space; and

     (b)  the product of the Annual Estimated Operating Costs per rentable
          square foot times the Rentable Floor Area of Tenant's Space.

                                       21
<PAGE>   25

     If, with respect to any Fiscal Year or fraction thereof during the Term,
Tenant is obligated to pay Operating Cost Escalation, then Tenant shall pay, as
additional rent, on the first day of each month of each ensuing Fiscal Year
thereafter, until Landlord's Statement for an ensuing Fiscal Year reflects that
Tenant is not obligated to pay Operating Cost Escalation, Estimated Monthly
Escalation Payments equal to 1/12th of the annualized Operating Cost Escalation
for the immediately preceding Fiscal Year, Estimated Monthly Escalation Payments
for each ensuing Fiscal Year shall be made retroactively from the first day of
such Fiscal Year and on account of the payment to be made pursuant to the first
sentence of this Section 4.2 for such Fiscal Year, with an appropriate
additional payment or refund to be made at the time such payment is due.

     The term "Fiscal Year" as used in this Article shall mean the period of
twelve (12) consecutive months commencing on January 1 and ending on December
31.

     The term "real estate taxes" as used above shall mean all ad valorem real
estate taxes assessed by any governmental authority on the Lot, the Building and
improvements, or both, and the Common Areas of the Park, subject to the
following: There shall be excluded from such taxes (i) any governmental or
business park "special assessments" (i.e. roads and sewers) not considered to be
"property" taxes hereunder, and (ii) all income taxes, excess profits taxes,
excise taxes, franchise taxes, estate, succession, inheritance and transfer
taxes, provided, however, that if at any time during the Term the present system
of ad valorem taxation of real property shall be changed so that in lieu of the
whole or any part of the ad valorem tax on real property, there shall be
assessed on Landlord a capital levy or other tax on the gross rents received
with respect to the Lot, Building and improvements, or both, and the Common
Areas of the Park, a federal, state, county, municipal, or other local income,
franchise, excise or similar tax, assessment, levy or charge (distinct from any
now in effect) measured by or based, in whole or primarily, upon any such gross
rents, then any and all of such taxes, assessments, levies or charges, to the
extent so measured or based, shall be deemed to be included within the term
"real estate taxes".

     If the total of the monthly payments paid by Tenant with respect to any
Fiscal Year exceeds the actual Operating Cost Escalation for such Fiscal Year,
then, at Landlord's option, such excess shall be either (i) credited against
payments on account of Operating Cost Escalation next due hereunder, or (ii)
refunded by Landlord to Tenant.

     The amount of any refund of real estate taxes shall be credited against
real estate taxes for the Fiscal Year in which such refund is received;
provided, however, in the event that Landlord receives a refund on account of
real estate taxes after the expiration of the Term, which refund relates to a
Fiscal Year during the Term, the amount of such refund fairly allocable to
Tenant shall be refunded to Tenant by Landlord. All references to real estate
taxes "for" a particular Fiscal Year shall be deemed to refer to real estate
taxes due and payable during such Fiscal Year without regard to when such
impositions are assessed or levied.

     All records that the Landlord is required to maintain hereunder shall be
maintained by the Landlord for a period of two (2) years following the
expiration of the Fiscal Year to which such records relate. Tenant shall have
the right, through its representatives, but not an obligation, to examine, copy
and audit such records at reasonable times, but no more than once per Fiscal
Year,

                                       22
<PAGE>   26

upon not less than thirty (30) days prior written notice. Such records shall be
maintained at Landlord's Address set forth in Section 1.1, or such other place
within the Commonwealth of Massachusetts as Landlord shall designate from time
to time for the keeping of such records. The costs of such audits shall be borne
by Tenant; provided, however, that if such audit establishes that the actual
Operating Cost Escalation for the Fiscal Year in question is less than the
Landlord's final determination of the Operating Cost Escalation as set forth in
the Landlord's Statement submitted to Tenant by at least ten (10%) percent, then
Landlord shall pay the reasonable cost of such audit. If, as a result of such
audit, it is determined that Tenant must pay additional amounts to Landlord on
account of the Operating Cost Escalation, or that Tenant has overpaid Landlord
on account of the Operating Cost Escalation, then the undercharged or overpaid
party shall reimburse the other party for the payment due, together with
interest thereon from the date of Landlord's Statement at the interest rate set
forth in Section 4.3 hereof. In no event shall the provisions of this paragraph
require Tenant to complete any such audit.

     Notwithstanding anything contained to the contrary in this Lease, the
initial responsibility for the payment of all real estate taxes with respect to
the Building and the Park shall be upon the Landlord and the Landlord agrees to
pay the same as required by law. Landlord shall provide Tenant with a
computation of Tenant's pro rata share thereof, and upon Tenant's request,
copies of all tax bills.

     Landlord shall have the right from time to time to change the periods of
accounting under this Section 4.2 to any annual period other than the Fiscal
Year and upon any such change all items referred to in this Section shall be
appropriately apportioned. In all Landlord's Statements, rendered under this
Section, amounts for periods partially within and partially without the
accounting periods shall be appropriately apportioned, and any items which are
not determinable at the time of a Landlord's Statement shall be included therein
on the basis of Landlord's estimate, and with respect thereto Landlord shall
render promptly after determination a supplemental Landlord's Statement, and
appropriate adjustment shall be made according thereto. All Landlord's
Statements shall be prepared in accordance with GAAP.

     Notwithstanding any other provision of this Section 4.2, if the Term
expires or is terminated as of a date other than the last day of a Fiscal Year
at the end of the Term, Tenant's last payment to Landlord under this Section 4.2
shall be made on the basis of Landlord's best estimate of the items otherwise
includable in Landlord's Statement and shall be made on or before the later of
(a) ten (10) days after Landlord delivers such estimate to Tenant, or (b) the
last day of the Term, with an appropriate payment or refund to be made upon
submission of Landlord's Statement. Without limitation, the obligation of Tenant
to pay the Operating Cost Escalation with respect to any Fiscal Year during the
Term (or portion thereof) shall survive the expiration or earlier termination of
the Term.

4.3  PAYMENTS

     All payments of Fixed Rent and additional rent shall be made to Managing
Agent, or to such other person as Landlord may from time to time designate in
writing. If any installment of rent, Fixed Rent or additional, or on account of
leasehold improvements is paid more than five

                                       23
<PAGE>   27

(5) business days after the due date thereof, at Landlord's election, it shall
bear interest at the rate of eighteen percent (18%) per annum (or, if lower, the
maximum rate permitted by law).

                                    ARTICLE V
                              LANDLORD'S COVENANTS

5.1  LANDLORD'S COVENANTS DURING THE TERM

     Landlord covenants during the Term:

     5.1.1 Building Services - To furnish, through Landlord's employees or
           independent contractors, the services listed in Exhibit D;

     5.1.2 Additional Building Services - To furnish, through Landlord's
           employees or independent contractors, reasonable additional Building
           operation services upon reasonable advance request of Tenant at
           reasonable and competitive rates from time to time established by
           Landlord to be paid by Tenant;

     5.1.3 Repairs - Except as otherwise provided in Article VII, except as
           resulting from Tenant's negligence or misuse, except as resulting
           from settling or sagging within standard engineering tolerance
           (provided that the settling or sagging does not affect the surface or
           structural integrity of the Building or in any way materially affect
           the ordinary and customary use of the Premises, or any part thereof
           by Tenant), or except for damage or deterioration resulting from
           reasonable wear and damage, Landlord shall keep in good order,
           condition and repair, the roof of the Building, all gutters and
           downspouts, foundations, exterior (including exterior painting and
           finish) and structural portions of the Building, all Building systems
           serving the Building, and all plumbing and utility lines serving the
           Premises, whether located within or outside of the Premises. The
           Landlord's obligations shall include, without limitation, the
           obligation to make all necessary repairs, replacements or alterations
           to the roof, the exterior walls, the foundation, the floor slabs and
           all other structural elements of the Building, to maintain the
           Building Parking Area and to maintain in good order and condition the
           Lot and the other lots, buildings and improvements located within the
           Park, including but not limited to the Common Areas of the Park (e.g.
           parking areas, passageways, driveways, sidewalks, roadways, and sewer
           treatment plant). Landlord shall maintain in good operating condition
           throughout the Term, reasonable wear and tear excepted, repair and
           replace the HVAC equipment in the Building, in accordance with the
           requirements of the Landlord's Plans (expressly excluding the HVAC
           system(s), if any, not specifically described in Landlord's Plans,
           (i) unless otherwise mutually agreed upon by Landlord and Tenant in
           writing or (ii) unless the parties determine that it is difficult or
           in practical to maintain the HVAC system(s) separately, the parties
           hereby agreeing in such event that Landlord shall maintain all HVAC
           systems and shall charge Tenant the incremental cost thereof pursuant
           to Section 4.2 hereof), and shall assign (to the extent assignable)
           all

                                       24
<PAGE>   28

           warranties and guarantees with respect thereto to Tenant. Tenant may
           elect, at its cost and expense and upon the prior consent of Landlord
           (which such consent shall not be unreasonably withheld or delayed),
           to bring actions to enforce remedies under said warranties or
           guarantees in the name of the Landlord or jointly with Landlord, at
           no expense to Landlord;

     5.1.4 Quiet Enjoyment - That Landlord has the right to make this Lease and
           that Tenant, on paying the rent and performing its obligations
           hereunder, shall peacefully and quietly have, hold and enjoy the
           Premises throughout the Term without any manner of hindrance or
           molestation from Landlord or anyone claiming under Landlord, subject,
           however, to all the terms and provisions hereof;

     5.1.5 Intentionally Deleted.

     5.1.6 Landlord's Insurance - Beginning with the commencement of Landlord's
           Work and thereafter throughout the Term, Landlord shall purchase and
           keep in force, broad-form commercial general liability insurance, or
           the equivalent then-customary form providing comparable coverages,
           written out on an occurrence basis containing provisions adequate to
           protect the Landlord from and against claims for bodily injury,
           including death and personal injury and claims for property damage
           occurring within the Park and/or the Building, such insurance having
           body injury and property damage combined limits of not less than five
           million dollars ($5,000,000) per occurrence. In addition, Landlord
           shall procure and continue in force during the Term, as the same may
           be extended hereunder, fire and extended coverage insurance,
           including vandalism, sprinkler leakage and malicious mischief, upon
           the Building on a full replacement cost basis, agreed cost value
           endorsement with agreed values for the Building and other tenant
           improvements and alterations, as determined annually by the
           Landlord's insurer. Landlord shall also procure and continue in force
           during the Term, as the same may be extended hereunder, rental
           interruption insurance for twelve (12) months or the maximum amounts
           permitted. Copies of certificates of insurance evidencing the
           foregoing shall be furnished to Tenant, upon Tenant's reasonable
           request. All insurance required of Landlord pursuant to this Section
           shall be effected under policies issued by insurers or recognized
           responsibility (which are rated A or A+ by Best's Rating Service or a
           comparable rating by an equivalent service). The coverages required
           by this Section 5.1.6 may be provided by a single "package policy";

     5.1.7 Landlord's Indemnity - Landlord covenants and agrees to defend, with
           counsel reasonably acceptable to Tenant, save harmless and indemnify
           Tenant from any liability for injury, loss, accident or damage to any
           person or property on the Premises or the Park, and from any claims,
           actions, proceedings and reasonable expenses and costs in connection
           therewith (including, without implied limitation, reasonable counsel
           fees), arising directly from the negligent acts and/or willful

                                       25
<PAGE>   29

           misconduct of Landlord not caused directly by the negligent acts or
           willful misconduct of Tenant. In no event shall Landlord be obligated
           to indemnify Tenant for any willful or negligent act or omission of
           Tenant or of any of Tenant's employees, agents, contractors or
           licensees;

     5.1.8 Hazardous Materials - Landlord represents and warrants that, to the
           best of Landlord's knowledge as of the date of this Lease and as of
           the date of Substantial Completion (i) there does not exist (and will
           not exist as of the date of Substantial Completion) any leak, spill,
           release, discharge, emissions or disposal of Hazardous Materials on
           the Lot (including the Building to be located thereon), and (ii) the
           Premises do not (and will not as of the date of Substantial
           Completion) contain any Hazardous Materials, except as may be
           contained in customary cleaning supplies or in such other supplies
           (e.g. paint) that are necessary for Landlord to perform its
           obligations hereunder. In the event that any such leak, spill,
           release, discharge, emission or disposal of Hazardous Materials shall
           occur on the Lot or (apart from DE MINIMIS amounts of such materials
           used for cleaning and maintenance purposes or in connection with the
           operation of loading docks) the Park not caused by Tenant or its
           officers, employees, agents, contractors or licensees, Landlord shall
           take any and all actions necessary to bring the Premises, the Park
           and/or the Building (excluding all portions thereof leased or
           leasable to tenants) into compliance with applicable law and other
           governmental requirements relating thereto.

           Landlord agrees to notify Tenant immediately upon discovery of any
           Hazardous Materials on the Premises or in the Park and to indemnify,
           defend and hold harmless Tenant and its officers, employees and
           agents from and against any claims, judgments, damages, penalties,
           fines, costs, liabilities or loss (including without limitation
           reasonable attorneys' fees) which arise during or after the date
           hereof from or in connection with the presence or suspected presence
           of Hazardous Materials on the Premises or in the Park caused directly
           by the negligent acts or willful misconduct of Landlord.
           Notwithstanding any language to the contrary set forth in this Lease,
           in no event shall Landlord be obligated to indemnify Tenant for any
           Hazardous Materials which arise, as a result of the negligent acts or
           willful misconduct of Tenant, its officers, employees, agents,
           contractors or licensees. The covenants and indemnifications set
           forth in this Section 5.1.8 shall survive the expiration or earlier
           termination of this Lease; and

     5.1.9 Tenant's Costs - In case Tenant shall, without any fault on its part,
           be made party to any litigation commenced by or against Landlord or
           by or against any parties in possession of the Premises or any part
           thereof claiming under Landlord, Landlord agrees to reimburse Tenant
           for all reasonable costs, including without implied limitation,
           reasonable counsel fees, incurred by or imposed upon Tenant in
           connection with such litigation and to pay all such reasonable costs
           and fees incurred in connection with the successful enforcement by
           Tenant of any obligations of Landlord under this Lease.

                                       26
<PAGE>   30

     Except as specifically provided to the contrary in Section 4.2, Landlord
shall charge Tenant under the provisions of Section 4.2 for the costs incurred
by Landlord in connection with the services and/or repairs set forth in Sections
5.1.1, 5.1.2, 5.1.3 and 5.1.6 above; provided, however, Landlord shall be
responsible to pay the following, at its sole cost and expense: (i) repairs or
replacements which are necessary to maintain the structural integrity of the
Building and the roof during the Term of this Lease (expressly including any
renewal terms hereunder), and (ii) maintenance and repairs (and replacements, if
necessary) during the initial one (1) year period (or three (3) year period as
to latent defects) described in Section 3.7 or otherwise covered by Landlord's
or manufacturers warranties described in Section 3.7 above.

5.2  INTERRUPTIONS

     Except as otherwise set forth below in this Section 5.2, Landlord shall not
be liable to Tenant for any compensation or reduction of rent by reason of
inconvenience or annoyance or for loss of business arising from power losses or
shortages or from the necessity of Landlord's entering the Premises for any of
the purposes in this Lease authorized, or for repairing the Premises or any
portion of the Building or Lot. In case, notwithstanding Landlord's diligent
efforts in connection therewith (which such efforts shall never obligate
Landlord to pay for overtime and/or premium time work, or to pay a premium for
expedited delivery, except as such additional costs are so authorized and paid
for by Tenant), Landlord is prevented or delayed from making any repairs,
alterations or improvements, or furnishing any service or performing any other
covenant or duty to be performed on Landlord's part, by reason of any cause
reasonably beyond Landlord's control (expressly excluding Landlord's financial
inability), Landlord shall not be liable to Tenant therefore, nor, except as
expressly otherwise provided in Article III or Article VII, shall Tenant be
entitled to any abatement or reduction of rent by reason thereof, nor shall the
same give rise to a claim in Tenant's favor that such failure constitutes,
actual or constructive, total or partial, eviction from the Premises.

     Landlord reserves the right to stop any service or utility system when
necessary by reason of accident or emergency or until necessary repairs have
been completed. Except in case of emergency repairs, Landlord will give Tenant
reasonable advance notice of any contemplated stoppage and will use reasonable
efforts to avoid unnecessary inconvenience to Tenant by reason thereof.

     Notwithstanding any language to the contrary, if, due solely to any act or
omission on the part of Landlord, electricity, heat, air conditioning, water or
any other service or utility that Tenant is entitled to receive under this Lease
is interrupted, and such interruption renders the Premises untenantable, or any
portion thereof is reasonably inaccessible by Tenant, or makes it impracticable
for Tenant to conduct its business in the Premises, then if such interruption or
cessation shall continue for a period of thirty (30) consecutive days after
notice thereof from Tenant to Landlord that the Premises are untenantable, or
reasonably inaccessible, or Tenant cannot conduct its business as a result
thereof, then the Fixed Rent and additional rent shall be proportionately abated
for each successive day such interruption or cessation continues based upon that
certain portion of the Premises that are affected by such interruption (other
than for

                                       27
<PAGE>   31

reasons of casualty or eminent domain where the provisions of Article VII shall
govern). In addition, in the event that any such interruption or cessation shall
continue for more than ninety (90) successive days, after notice thereof from
Tenant to Landlord that the Premises are untenantable, or reasonably
inaccessible, or Tenant cannot conduct its business as a result thereof, then
Tenant shall have the right to cancel this Lease by giving written notice to
Landlord and its mortgagee(s) (of which Tenant has received written notice) of
such cancellation, provided that at least ten (10) days prior written notice to
Landlord and thirty (30) days prior written notice to Landlord's mortgagee has
been given (which such notice may be given prior to or after the expiration of
said ninety (90) day period), unless within such ten (10) day period Landlord
repairs or restores such interruption as herein required, in which event such
notice of cancellation from Tenant shall be rendered null and void and of no
further force or effect. For purposes of this Section, Landlord and Tenant
hereby acknowledge and agree that if the Premises (or portion thereof) is
rendered inaccessible by elevator, but accessible by stairway(s), then the
Premises (or such portion) will not be deemed "reasonably inaccessible" for the
purposes hereof.

     Notwithstanding anything to the contrary contained in this Section 5.2, in
no event shall Tenant be entitled to any such abatement or reduction of rent or
to any such right of termination if such interruption resulting in the Premises
being untenantable or unfit for Tenant's business operations therein is due to
an event of default by Tenant as set forth in Section 9.1 hereof or is not due
to any act or omission on the part of Landlord. Except as set forth in this
Section 5.2 or in Article VII, the foregoing rights shall be Tenant's sole
remedy at law or in equity for any interruptions described in this Section 5.2.

                                   ARTICLE VI
                               TENANT'S COVENANTS

6.1  TENANT'S COVENANTS DURING THE TERM

     Tenant covenants during the Term:

     6.1.1 Tenant's Payments - To pay when due (a) all Fixed Rent and additional
           rent, (b) all taxes which may be imposed on Tenant's personal
           property in the Premises (including, without limitation, Tenant's
           fixtures and equipment) (c) directly to the utility provider (if not
           payable to Landlord), subject however, to Tenant's right to contest
           and seek abatement thereof, all charges by public utility for
           telephone and other utility services (including service inspections
           therefor and the charges as may be imposed pursuant to Exhibit D
           hereof including all electric and gas consumed on the Premises)
           rendered to the Premises not otherwise required hereunder to be
           furnished by Landlord without charge and not consumed in connection
           with any services required to be furnished by Landlord without
           charge, and (d) as additional rent, all reasonable charges of
           Landlord for services rendered pursuant to Section 5.1.1, 5.1.2,
           5.1.3, and 5.1.6 hereof, except as set forth in the last paragraph of
           Section 5.1.

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<PAGE>   32

     6.1.2 Repairs and Yielding Up - Except as otherwise provided in Article VII
           and Section 5.1.3, to keep the interior, non-structural and
           non-building system elements of the Premises in good order, repair
           and condition, reasonable wear and damage or destruction by casualty
           or eminent domain excepted, and at the expiration or termination of
           this Lease peaceably to yield up the Premises and all changes and
           additions therein in such order, repair and condition, first removing
           all goods and effects of Tenant and any items, the removal of which
           is required by agreement or specified therein to be removed at
           Tenant's election and which Tenant elects to remove, Landlord and
           Tenant hereby acknowledging and agreeing, however, that the initial
           improvements constructed by Landlord pursuant to Article III and
           described in Landlord's Plans and Tenant's Plans referenced therein
           (including without limitation any cafeteria(s) and laboratories)
           shall not be required to be removed by Tenant upon expiration of the
           Term, as hereinbefore provided in Section 3.1, and repairing all
           damage caused by such removal and leaving them clean and neat; any
           property not so removed shall be deemed abandoned and may be removed
           and disposed of by Landlord, in such manner as Landlord shall
           determine, and Tenant shall pay Landlord the entire reasonable cost
           and expense incurred by it by effecting such removal and disposition;

     6.1.3 Occupancy and Use - To use and occupy the Premises only for the
           Permitted Uses; and not to injure or deface the Premises, Building or
           Lot; and not to permit in the Premises any auction sale, nuisance, or
           the emission from the Premises of any objectionable noise or odor,
           nor to permit any use thereof which is improper, offensive, contrary
           to law or ordinances, or liable to invalidate or increase the
           premiums for any insurance on the Building or its contents or liable
           to render necessary any alteration or addition to the Building,
           unless Tenant agrees to pay such increased premiums and/or costs, and
           such use (if other than Permitted Uses) is approved by Landlord in
           advance;

     6.1.4 Rules and Regulations - To comply with the Rules and Regulations set
           forth in Exhibit E and all other reasonable Rules and Regulations
           hereafter made by Landlord, of which Tenant has been given notice,
           for the care and use of the Building, Lot and Common Areas of the
           Park (and their facilities and approaches as further described in the
           Park Covenants attached hereto as Exhibit I), it being understood
           that Landlord shall not be liable to Tenant for the failure of other
           tenants of the Building or Park to conform to such Rules and
           Regulations; provided that (i) such Rules and Regulations are
           enforced in a non-discriminatory fashion, (ii) such Rules and
           Regulations do not materially interfere with or otherwise diminish
           Tenant's use of the Premises and the Building Parking Area or
           Tenant's rights under this Lease, (iii) result in no additional cost
           or expense to Tenant, and (iv) do not impose any additional
           obligation on Tenant.

     6.1.5 Compliance with Laws and Safety Appliances - To keep, from and after
           the initial installation thereof by Landlord, subject to the
           provisions of Section 10.18 (c), the

                                       29
<PAGE>   33

           Premises equipped with all safety appliances required by law or
           ordinance or any other regulation of any and public authority because
           of any particular manner of use made by Tenant and to procure and
           comply with all licenses and permits so required because of such use,
           it being understood that the foregoing provisions shall not be
           construed to broaden in any way Tenant's Permitted Uses. Tenant shall
           have the right, upon giving notice to the Landlord, to contest any
           obligation imposed upon it pursuant to the provisions of this Section
           6.1.5, and provided the enforcement of such requirement or law is
           stayed during such contest and such contest will not subject the
           Landlord to penalty or jeopardize the title to the Premises or
           otherwise affect the Premises in any adverse way. Landlord shall
           cooperate with Tenant in such contest and shall execute any documents
           reasonably required in the furtherance of such purpose.
           Notwithstanding the foregoing or any other provision of this Lease,
           however, Tenant shall not be responsible for compliance with any such
           laws, regulations, or the like requiring (i) structural repairs or
           modifications or (ii) repairs or modifications to the utility or
           building service equipment located outside of and not exclusively
           serving the Premises or (iii) installation of new building service
           equipment, such as fire detection or suppression equipment, unless
           such repairs, modifications, or installations shall (a) be due to
           Tenant's Construction Work, alterations, or repairs in the Premises
           or Tenant's particular manner of use of the Premises (as opposed to
           commercial office operations, generally), or (b) be due to the
           negligence or willful misconduct of Tenant's or any agent, employee,
           or contractor of Tenant.

     6.1.6 Assignment and Subletting -Tenant shall have the right, subject to
           the requirement of obtaining Landlord's prior written consent, such
           consent not to be unreasonably withheld or delayed by Landlord, to
           assign this Lease or sublet the whole or any portion of the Premises,
           which assignment or sublease shall be only for the Permitted Uses, it
           being understood that Tenant shall, as additional rent, reimburse
           Landlord promptly for reasonable legal and other expenses incurred by
           Landlord in connection with any request by Tenant for consent to
           assignment or subletting. No assignment or subletting shall affect
           the continuing primary liability of Tenant (which, following
           assignment, shall be joint and several with the assignee). Such
           consent by Landlord to any of the foregoing in a specific instance
           (i) shall be reasonable, subject to the provisions hereinafter
           provided, and (ii) shall be subject to the prior written approval of
           Landlord's mortgagee(s). Landlord's consent shall not be treated as
           having been withheld unreasonably if, in connection with any such
           proposed assignment or subletting: (i) the terms of the proposed
           assignment or subletting do not prohibit further assignments of the
           Lease or subletting of the Premises without the written consent of
           Landlord, the granting of which consent shall be subject to the terms
           and conditions hereof, and in any event shall not be unreasonably
           withheld or delayed; and/or (ii) in connection with an assignment of
           this Lease, the assignee does not agree directly with Landlord, by
           written instrument in form reasonably satisfactory to Landlord, to be
           bound by all the obligations of Tenant hereunder including, without
           limitation, the covenant against further assignment and subletting
           without the

                                       30
<PAGE>   34

          written consent of Landlord; and/or (iii) the proposed assignment or
          subletting violates any exclusive use restrictions or exclusions of
          the Building or Park as set forth in Exhibit Q. Tenant hereby
          acknowledges and agrees that the foregoing is not intended to be an
          exclusive list of the reasons for which Landlord may reasonably
          withhold consent to a proposed request by Tenant for consent to
          assignment or subletting. No consent to any of the foregoing in a
          specific instance shall operate as waiver in any subsequent instance.

          If an assignment or subletting is proposed to be made and Landlord's
          consent is required as hereinabove provided, Tenant shall give
          Landlord prior notice of such proposal, which such notice shall
          include such information as Landlord may reasonably request relative
          to facts which would bear upon the factors entering into the
          determination whether Landlord's approval is to be granted, and it is
          understood that Landlord shall use diligent efforts within a period of
          thirty (30) days after the submission of such information by Tenant to
          make its determination whether Landlord's approval is to be granted
          hereunder. If Tenant requests Landlord's consent to assign this Lease
          or sublet more than sixty percent (60%) of the Premises, Landlord
          shall have the option, exercisable by written notice to Tenant given
          within thirty (30) days after receipt of such request, to recapture
          the portion of the Premises proposed to be assigned or sublet as of a
          date specified in such notice which shall be not less than forty-five
          (45), or more than sixty (60) days after the date of such notice, in
          such event the recaptured area of the Premises shall be removed from
          the Premises and Tenant shall have no further liabilities or
          obligations with respect thereto, including obligations to pay Fixed
          Rent, additional rent or other charges with respect thereto; and any
          rental received by Tenant from sub-tenant must be remitted to
          Landlord; provided, however, upon Tenant's receipt of any such written
          notice from Landlord exercising its right of recapture hereunder,
          Tenant shall have the option, exercisable by written notice to
          Landlord given within ten (10) days after receipt of such Landlord's
          notice, to withdraw its request to assign or sublet all or a portion
          of the Premises, whereupon Landlord's notice to Tenant exercising its
          right of recapture hereunder shall become null and void and of no
          force or effect as to Tenant's particular request for Landlord's
          consent hereunder.

          Notwithstanding any provision contained in this Lease, no consent of
          Landlord shall be required for the assignment of this Lease or the
          subletting of any portion (or the whole) of the Premises for the
          Permitted Uses, (i) to a subsidiary of Tenant, (ii) to a corporation
          or other entity into or with which Tenant has merged or consolidated
          or to which substantially all of Tenant's stock or assets are
          transferred, (iii) to any corporation or other entity which controls,
          is controlled by, or is under common control with Tenant, or (iv) to
          any corporation or other entity with which Tenant is otherwise
          affiliated (collectively, the "Permitted Transferees"); provided that,
          in any of such events, Tenant shall remain directly and primarily
          liable and any such sublessee or assignee agrees directly with
          Landlord by written instrument reasonably satisfactory to Landlord and
          such

                                       31
<PAGE>   35

          assignee or sublessee to be bound by all of the obligations of Tenant.
          In the event of any such assignment or subletting for which no consent
          by Landlord is required hereunder, Tenant shall not be obligated to
          share Rent Differential as hereinafter set forth, nor shall the
          recapture rights of Landlord set forth in the preceding paragraph be
          applicable.

          If this Lease shall be assigned, or if the Premises or any part hereof
          shall be sublet or occupied by any person other than Tenant, Landlord
          may, at any time and from time to time, collect rent from the
          assignee, subtenant or occupant and apply the net amount collected to
          the annual Fixed Rent, additional rent and all other charges herein
          reserved, but no such assignment, subletting, occupancy or collection
          shall be deemed a waiver of the provisions of this Section 6.1.6, or
          acceptance of the assignee, subtenant or occupant as tenant, or a
          release of Tenant from the further performance of the terms, covenants
          and conditions of this Lease on the part of Tenant to be performed.
          Further, no liability hereunder of Tenant shall be discharged,
          reduced, released or impaired in any respect by any waiver, indulgence
          or extension of time which Landlord may grant to the then owner of
          Tenant's interest in this Lease, whether or not notice thereof has
          been given or consent from Tenant has been obtained.

          Landlord shall have the option to require that any portion of rental
          received by Tenant from subtenant or assignee to which Landlord is
          entitled pursuant to this Section 6.1.6 be remitted directly to
          Landlord, provided that such amounts are credited pro tanto against
          Tenant's rental obligations.

          If Landlord approves a sublease or assignment, and said sublease or
          assignment is for a total rental amount which on an annualized basis
          is greater than the Fixed Rent and additional rent due from Tenant to
          Landlord under this Lease, Tenant shall pay to Landlord, forthwith
          upon Tenant's receipt of each installment of such excess rent, during
          the term of any approved sublease or assignment, as additional rent
          hereunder, in addition to the Fixed Rent and other payments due under
          this Lease, an amount equal to fifty percent (50%) of the positive
          excess between all fixed rent and additional rent received by Tenant
          under the sublease or assignment and the Fixed Rent and the additional
          rent due hereunder after Tenant has recouped its reasonable
          out-of-pocket expenses with respect to such sublease or assignment,
          including without limitation, reasonable real estate brokerage
          commissions, reasonable legal fees, reasonable free rent, reasonable
          marketing costs and the reasonable costs of refurbishment of the
          Premises for such sublease or assignment (the "Rent Differential"). In
          the event the sublease is for less than the full Premises hereunder,
          the above rent adjustment shall be equitably pro rated on a square
          foot basis. Anything contained in the foregoing provisions of this
          section to the contrary notwithstanding, neither Tenant nor any other
          person having interest in the possession, use, occupancy or
          utilization of the Premises shall enter into any lease, sublease,
          license, concession or other agreement for use, occupancy or
          utilization of space in the Premises which provides for rental or

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<PAGE>   36

            other payment for such use, occupancy or utilization based, in whole
            or primarily on the net income or profits derived by any person from
            the Premises leased, used, occupied or utilized (other than an
            amount based on a fixed percentage or percentages of receipts or
            sales), and any such purported lease, sublease, license, concession
            or other agreement shall be absolutely void and ineffective as a
            conveyance of any right or interest in the possession use, occupancy
            or utilization of any part of the Premises;

     6.1.7  Indemnity - To defend, with counsel reasonably acceptable to
            Landlord, save harmless, and indemnify Landlord from any liability
            for injury, loss, accident or damage to any person or property
            occurring on the Premises, in the Building, or elsewhere in the
            Park, and from any claims, actions, proceedings and expenses and
            costs in connection therewith or elsewhere in the Park (including,
            without implied limitation, reasonable counsel fees): (i) arising
            from the negligent acts or gross misconduct of Tenant or any of
            Tenant's employees, agents, contractors, licensees or invitees and
            not caused directly by the negligent acts or gross misconduct of
            Landlord, or (ii) resulting from the failure of Tenant to perform
            and discharge its covenants and obligations under this Lease. In no
            event shall Tenant be obligated to indemnify Landlord for any
            willful or negligent act or omission of Landlord or any of
            Landlord's employees, agents, contractors or licensees. The
            covenants and indemnifications set forth in this Section 6.1.7 shall
            survive the expiration or earlier termination of this Lease;

     6.1.8  Tenant's Liability Insurance - To maintain public liability
            insurance in the Premises in amounts which shall, at the beginning
            of the Term, be at least equal to the limits set forth in Section
            1.1 and from time to time during the Term, shall be for such higher
            limits, if any, as are customarily carried in the area in which the
            Premises are located on property similar to the Premises and used
            for similar purposes and, upon written request therefor, to furnish
            Landlord (and/or its mortgagees) with certificates thereof;

     6.1.9  Tenant's Workmen's Compensation Insurance - To keep all Tenant's
            employees working in the Premises covered by workmen's compensation
            insurance in statutory amounts and to furnish Landlord with
            certificates thereof;

     6.1.10 Landlord's Right of Entry - Upon not less than twenty-four (24)
            hours advance notice (except in the event of emergencies), at times
            reasonably acceptable to Landlord and Tenant, to permit Landlord and
            Landlord's agents entry; to examine the Premises at reasonable times
            and, if Landlord shall so elect, to make repairs or replacements; to
            remove, at Tenant's expense, any changes, additions, signs,
            curtains, blinds, shades, awnings, aerials, flagpoles, or other
            improvements visible outside the Building not consented to in
            writing by Landlord (Landlord hereby acknowledging that the initial
            improvements constructed by Landlord pursuant to Article III shall
            be permitted and may remain upon expiration of the Term as
            hereinbefore provided in Sections 3.1 and 6.1.2); and to show the
            Premises to

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<PAGE>   37

            prospective tenants during the twelve (12) months preceding
            expiration of the Term and to prospective purchasers and mortgagees
            at all reasonable times;

     6.1.11 Loading - Not to place a load upon the Premises exceeding an average
            rate of one hundred (100) pounds of live load per square foot of
            floor area; and not to move any safe, vault or other heavy equipment
            in, about or out of the Premises except in such a manner and at such
            times as Landlord shall in each instance approve; Tenant's business
            machines and mechanical equipment which cause vibration or noise
            that may be transmitted to the Building structure shall be placed
            and maintained by Tenant in settings of cork, rubber, spring, or
            other types of vibration eliminators sufficient to eliminate such
            vibration or noise;

     6.1.12 Landlord's Costs - In case Landlord shall, without any fault on its
            part, be made party to any litigation commenced by or against Tenant
            or by any party claiming under Tenant, to pay, as additional rent,
            all actual third party reasonable costs including, without implied
            limitation, reasonable counsel fees incurred by or imposed upon
            Landlord in connection with such litigation, and, as additional
            rent, also to pay all such reasonable costs and fees incurred by
            Landlord in connection with the successful enforcement by Landlord
            of any obligations of Tenant under this Lease;

     6.1.13 Tenant's Property - All the furnishings, fixtures, equipment,
            effects and property of every kind, nature and description of Tenant
            and of all persons claiming by, through or under Tenant which,
            during the continuance of this Lease or any occupancy of the
            Premises by Tenant or anyone claiming under Tenant, may be on the
            Premises or on the Lot shall be at the sole risk and hazard of
            Tenant, except for Landlord's gross negligence or willful act or
            omission, and if the whole or any part thereof shall be destroyed or
            damaged by fire, water or otherwise, or by the leakage or bursting
            of water pipes, steam pipes, or other pipes, by theft, or from any
            other cause, no part of said loss or damage is to be charged to or
            to be borne by Landlord, except if caused directly by Landlord's
            gross negligence or willful misconduct;

     6.1.14 Labor or Materialmen's Liens - To pay promptly when due the entire
            cost of any work done on the Premises by Tenant, its agents,
            employees, or independent contractors; not to cause or permit any
            liens for labor or material performed or furnished in connection
            therewith to attach to the Premises; and within ten (10) days after
            Tenant's receipt of notice thereof, to discharge or bond over any
            such liens which may so attach;

     6.1.15 Changes or Additions - Not to make any material changes or additions
            to the Premises without Landlord's prior written consent, which such
            consent shall not be unreasonably withheld or delayed.
            Notwithstanding the foregoing, Tenant may, from time to time, at its
            own cost and expense and without the consent of Landlord, make
            non-structural alterations, additions or improvements to the

                                       34
<PAGE>   38

          Premises, so long as they do not affect any of the mechanical,
          electrical or plumbing systems of the Building (collectively herein
          called "Alterations") whose cost in any one instance is Twenty-Five
          Thousand Dollars ($25,000.00) or less, provided that Tenant first
          notifies Landlord in writing of any such Alterations. If Tenant
          desires to make any Alterations costing in excess of Twenty-Five
          Thousand Dollars ($25,000.00) in any one instance or any other
          alteration, including any structural alteration or alteration
          affecting any of the mechanical, electrical or plumbing systems of the
          Building, Tenant must first obtain the consent of Landlord thereto,
          which consent shall not be unreasonably withheld or delayed. If
          Landlord reasonably concludes that the Alterations involve any
          construction, alterations or additions requiring unusual expense to
          readapt the Premises to normal office use on the Term Expiration Date,
          Landlord shall notify Tenant in writing at the time of approval that
          such readaptation will be required to be made by Tenant prior to such
          Term Expiration Date without expense to Landlord.

          Any and all such alterations, including, Alterations may be done by
          any contractor chosen by Tenant provided any such contractor is
          reputable, bondable by reputable bonding companies, carries the kind
          of insurance and in the amounts set forth herein, and will work in
          harmony with Landlord's contractors and laborers in the Building;

          Tenant in making any alterations, including Alterations, shall cause
          all work to be done in a good and workmanlike manner using materials
          substantially equal to or better than those used in the construction
          of the Premises or original Tenant's Work and shall comply with or
          cause compliance with all laws and with any direction given by any
          public officer pursuant to law. Tenant shall obtain or cause to be
          obtained and maintain in effect, as necessary, all building permits,
          licenses, temporary and permanent certificates of occupancy and other
          governmental approvals which may be required in connection with the
          making of the alterations, including the Alterations. Landlord shall
          cooperate with Tenant in the obtaining thereof and shall execute any
          documents reasonably required in furtherance of such purpose, provided
          any such cooperation shall be without expense and/or liability to
          Landlord.

          At least annually if such Alterations or any other alterations
          hereunder have occurred during the past calendar year, Tenant shall
          furnish to Landlord as-built sepias and, if applicable, operating
          manuals, or, at Landlord's option and only if Tenant's computer system
          is compatible with that of Landlord's, computer disk specifications
          compatible with Landlord's computer system of the work done by Tenant
          during such past year and copies of all permits issued in connection
          therewith.

          Tenant shall have its contractor procure and maintain in effect during
          the term of such alterations, including Alterations, satisfactory
          insurance coverages with an

                                       35
<PAGE>   39

            insurance company or companies authorized to do business in the
            Commonwealth of Massachusetts, and shall, upon Landlord's request,
            furnish Landlord with certificates thereof;

     6.1.16 Holdover - To pay to Landlord two hundred percent (200%) the total
            of the Fixed and additional rent then applicable for each month or
            portion thereof Tenant shall retain possession of the Premises or
            any part thereof after the termination of this Lease, whether by
            lapse of time or otherwise and, also to pay all damages sustained by
            Landlord on account thereof; provided, however (i) Tenant shall be
            responsible to pay to Landlord only one hundred fifty percent
            (150%), and not two hundred percent (200%) as aforesaid, of the
            total Fixed Rent and additional rent then applicable for the first
            thirty (30) days Tenant retains possession of the Premises or any
            part thereof after termination of this Lease, and (ii) during such
            initial thirty (30) day period only, Landlord hereby acknowledges
            and agrees that no consequential damages shall be due from Tenant
            hereunder. The provisions of this subsection shall not operate as a
            waiver by Landlord of any right of re-entry provided in this Lease;

     6.1.17 Hazardous Materials - Tenant shall not (either with or without
            negligence) cause or permit the escape, disposal or release of any
            biologically or chemically active or other hazardous substances or
            materials onto the Premises or the Lot, except in accordance with
            the requirements of applicable laws and regulations. Tenant shall
            not allow the storage or use of such substances or materials in any
            manner not permitted by law, nor allow to be brought into the
            Premises any such materials or substances except to use in the
            ordinary course of Tenant's business. Upon Landlord's written
            request, Tenant shall furnish to Landlord an inventory of the
            identity of such substances or materials used in the ordinary course
            of Tenant's business. Without limitation, hazardous substances and
            materials shall include those described in the Comprehensive
            Environmental Response, Compensation and Liability Act of 1980, as
            amended, 42 U.S.C. Section 9601 et seq., the Resource Conservation
            and Recovery Act, as amended, 42 U.S.C. Section 6901 et seq., the
            Massachusetts Hazardous Waste Management Act, as amended, M.G.L.
            c.21C, the Massachusetts Oil and Hazardous Material Release
            Prevention and Response Act, as amended, M.G.L. c.21E, any
            applicable local ordinance or bylaw, and the regulations adopted
            under these acts, as amended (collectively, the "Hazardous Waste
            Laws"). If any lender or governmental agency shall ever require
            testing to ascertain whether or not there has been any release of
            hazardous substances or materials, then the reasonable costs thereof
            shall be reimbursed by Tenant to Landlord upon demand as additional
            charges if and only if the following conditions are satisfied; (i)
            if such requirement applies to the Premises and (ii) if an
            independent, reputable third party engineer employed by Landlord or
            persons acting under Landlord conclusively determines that such
            release had been or is likely to have been solely and exclusively
            caused by Tenant or persons acting under Tenant. If Tenant receives
            from any federal, state or local governmental agency any notice of
            violation or alleged violation of any Hazardous Waste Law,

                                       36
<PAGE>   40

            or if Tenant is obligated to give any notice under any Hazardous
            Waste Law, Tenant agrees to forward to Landlord a copy of any such
            notice within three (3) days of Tenant's receipt or transmittal
            thereof. In addition, Tenant shall execute affidavits,
            representations and the like from time to time at Landlord's request
            concerning Tenant's best knowledge of belief regarding the presence
            of hazardous substances or materials on the Premises. In all events,
            Tenant shall indemnify Landlord in the manner provided in Section
            6.1.7 of this Lease from any release of hazardous substances or
            materials on the Premises or elsewhere in the Park to the extent
            caused by Tenant or persons acting under Tenant. Landlord retains
            the right to inspect the Premises at all reasonable times, upon
            reasonable notice to Tenant, to ensure compliance with this
            paragraph. The within covenants shall survive the expiration or
            earlier termination of the Lease Term;

     6.1.18 Signs - Tenant shall not, without prior written consent of Landlord
            (which such consent shall not be unreasonably withheld or denied but
            may be withheld in Landlord's sole discretion if Tenant is not then
            leasing (including subleasing) one hundred percent (100%) of the
            initial Building, expressly excluding any expansion hereunder), (a)
            place any exterior signs visible outside the Building, on the Lot or
            the Premises or anywhere on the exterior of the Building, or (b)
            place any curtains, blinds (other than standard vertical blinds),
            shades, awnings, or flagpoles, or the like, in the Premises or
            anywhere on or in the Building visible from outside the Premises,
            except as otherwise expressly set forth below in this Section 6.1.18
            or elsewhere in this Lease. Tenant shall pay the expenses involved
            in the erection of any sign and of obtaining all necessary permits
            and approvals therefor. Except as otherwise provided below with
            respect to the initial Building signage, Tenant warrants that it
            shall obtain (and furnish copies thereof to Landlord) all necessary
            permits and approvals in compliance with local codes and ordinances
            prior to erecting any such sign(s). Tenant shall remove any of such
            sign(s) erected by Tenant or on behalf of Tenant upon the
            termination of this Lease.

            In connection with Tenant's initial Building signage, Landlord shall
            use reasonable efforts to obtain, on Tenant's behalf, all necessary
            permits and approvals required pursuant to local codes and
            ordinances for the building and site signage (i.e., two exterior
            signs on the Building and a monument sign consistent with the other
            signs in the Park). Tenant's signage on the Building shall be
            exclusive until such time as Tenant fails to lease (including
            subleasing) at least one hundred percent (100%) of the Building.
            Tenant shall reimburse Landlord for the actual third-party
            reasonable costs and expenses incurred by Landlord in connection
            with obtaining said permits and approvals, including reasonable
            attorneys fees and disbursements. Tenant agrees to cooperate with
            Landlord during the permitting process by (i) promptly executing the
            necessary documentation reasonably requested by Landlord, and (ii)
            by furnishing the same to Landlord promptly upon Landlord's request,
            but in no event later than seven (7) days following Landlord's
            request. Further, the construction and erection of any

                                       37
<PAGE>   41

            such signage shall be Tenant's sole responsibility and at Tenant's
            sole cost and expense;

     6.1.19 Tenant's Authority - Tenant has the power and authority to enter
            into this Lease and perform the obligations of Tenant hereunder.
            This Lease and all other documents executed and delivered by Tenant
            in connection herewith constitute legal, valid, binding and
            enforceable obligations of Tenant; and

     6.1.20 Confidentiality - This Lease document is a confidential document by
            and between Landlord and Tenant and Tenant agrees that this Lease
            shall not be copied and distributed or circulated to any person(s)
            other than to such parties, and their respective mortgagees,
            successors or assigns, their legal counsel or their accountants or
            to any prospective sublessees and assignees or affiliates of Tenant,
            or to any prospective acquirers, investors, or lenders of Tenant, or
            to regulatory authorities, or to the directors, shareholders or
            officers of Tenant, or as required by law, without the prior written
            consent of Landlord. Nothing contained in this Section shall
            prohibit the disclosure by Tenant of the essential terms of this
            Lease.

                                   ARTICLE VII
                               CASUALTY AND TAKING

7.1  CASUALTY AND TAKING

     In case during the Term all or any substantial part of the Premises, and/or
the Building Parking Area, or any part thereof, or both (i.e. in the case of a
fire or casualty, requiring greater than twelve (12) months to rebuild in
Landlord's reasonable judgment; or in the case of a condemnation or a taking,
more than thirty-five percent (35%) of the floor area of the Premises or any
material part of the means of access thereto or more than twenty-five percent
(25%) of Building Parking Area) are damaged by fire or any other casualty or by
action of public or other authority in consequence thereof or are taken by
eminent domain Landlord shall give prompt notice, (i.e. within thirty (30) days
thereof) to Tenant (the "Landlord's Notice") and this Lease shall terminate at
Tenant's election, which may be made by notice given to Landlord within thirty
(30) days after the date of Landlord's Notice, which termination shall be
effective (i) in the event of a casualty, not less than thirty (30) nor more
than sixty (60) days after the date of notice of such termination, and (ii) in
the event of eminent domain event, as of the date on which such taking becomes
effective and Tenant is deprived of the use and enjoyment of the Premises, or
part thereof, and/or the Building Parking Area, or part thereof. If in any such
case the Lease is not so terminated, Landlord shall proceed promptly and use due
diligence to put the Premises, or part thereof, and/or the Building Parking
Area, or part thereof, or in case of taking, what may remain thereof (excluding
any items installed by Tenant which Tenant may be permitted to remove upon the
expiration of the Term) into as near as possible to the condition and character
thereof prior to such damage or taking, and in any event shall apply all
insurance proceeds or eminent domain awards received by it toward such work, for
use and occupation to the extent permitted by the net award of insurance plus
any deductibles and such amounts as Tenant may

                                       38
<PAGE>   42

elect to make available for such work as hereinafter provided, or the amount of
the eminent domain award, and an equitable proportion of the Fixed Rent and
additional rent according to the nature and extent of the injury shall be abated
until the Premises or such remainder and the Building Parking Area shall have
been put by Landlord in such condition; and in case of a taking which
permanently reduces the area of the Premises, an equitable proportion of the
Fixed Rent and additional rent shall be abated for the remainder of the Term and
an appropriate adjustment shall be made to the Annual Estimated Operating Costs
and other additional rent payable hereunder.

     However, in the case of a casualty, if such damage is not repaired and the
Premises, or portion thereof, and/or Building Parking Area or part thereof,
restored to the same condition as they were prior to such damage within twelve
(12) months from the date of Landlord's Notice, then Tenant, within thirty (30)
days from the expiration of such twelve (12) month period or from the expiration
of any extension thereof by reason of any Tenant's Delay (as defined in Section
3.2 hereof) and/or Force Majeure (as defined in Section 3.5 hereof and subject
to the provisions set forth below) as hereinafter provided, may terminate this
Lease by notice to Landlord and Landlord's mortgagee(s), given in accordance
with Section 10.3 hereof, specifying a date not more than thirty (30) days after
the giving of such notice on which the Term of this Lease shall terminate.
Notwithstanding such termination notice by Tenant, in the event that Landlord
repairs such damage and restores the Premises to the same condition prior to
such casualty during such period, not to exceed thirty (30) days, as specified
in Tenant's notice, then such notice of termination given by Tenant to Landlord
hereunder shall be null and void and of no further force or effect. The period
within which the required repairs may be accomplished hereunder shall be
extended by (a) the number of days lost as a result of a Tenant's Delay, as
defined in and subject to the provisions of Section 3.2, with such term,
however, relating to restoration or repair as referenced herein and not to the
initial construction of the Building, and (b) the number of days lost as a
result of Force Majeure, as defined in Section 3.5 (up to a maximum of
forty-five (45) days in the aggregate as aforesaid).

     If less than a substantial part of the Premises or Lot, or portion thereof,
and/or the Building Parking Area, or portion thereof (i.e. in the case of a fire
or casualty, requiring less than twelve (12) months to rebuild in Landlord's
reasonable judgment; or in the case of a condemnation or taking thirty-five
percent (35%) or less of the floor area of the Premises or any part of the means
of access thereto or twenty-five percent (25%) or less of the Building Parking
Area) are damaged by fire or any other casualty or are taken by eminent domain,
then Landlord shall give prompt notice (i.e. within thirty (30) days) thereof to
Tenant, which notice shall specify Landlord's estimation of the time period
within which such repairs shall be completed, and thereafter Landlord shall
proceed promptly and with due diligence to the extent permitted by the net award
of insurance plus any deductible amounts and such amount as Tenant may elect to
make available for such work as hereinafter provided, or the amount of the
eminent domain award. In the event that Landlord fails to repair such damage and
restore the Premises to substantially the same condition prior to such fire and
other casualty within the time period as reasonably estimated by Landlord, but
in no event greater than such twelve (12) month period from the date of such
Landlord's notice to Tenant, or any extension thereof permitted for delays lost
due to any Tenant's Delay and/or Force Majeure (as hereinbefore provided), then
Tenant

                                       39
<PAGE>   43

may terminate this Lease by written notice to Landlord and to Landlord's
mortgagee(s), as provided in Section 10.3 hereof, specifying a date not more
than thirty (30) days after the giving of such notice on which the Term of this
Lease shall terminate. Notwithstanding such termination notice by Tenant, in the
event that Landlord repairs such damage and restores the Premises to
substantially the same condition prior to such fire or other casualty during
such period, not to exceed thirty (30) days, as specified in Tenant's notice,
then such notice of termination given by Tenant to Landlord hereunder shall be
null and void and of no further force and effect. If less than a substantial
part of the Premises and/or the Building Parking Area shall be so damaged, then
Fixed Rent and additional rent due hereunder shall be equitably abated until the
Premises and/or the Building Parking Area are so restored as set forth
hereunder.

     Landlord's architect's certificate, given in good faith, shall be deemed
conclusive statements therein contained and binding upon Tenant with respect to
the performance and completion of any repair or restoration work undertaken by
Landlord pursuant to this Section, except in the event of disagreement between
Landlord and Tenant relating to this Section, in which event the dispute
resolution provisions of Section 3.6 shall apply.

     Notwithstanding any language to the contrary, Landlord may construct
"Replacement Parking" pursuant to the following: If not more than thirty-five
percent (35%) of the Building Parking Area shall be so damaged, taken,
appropriated, or condemned as aforesaid, then Landlord or Tenant may elect to
provide Replacement Parking and render Tenant's notice of termination nugatory
(if applicable) by, within thirty (30) days following the effective date of such
destruction, taking, appropriation or condemnation, giving to Tenant notice in
writing that Landlord will, at Landlord's expense, construct replacement parking
spaces of the same quantity and quality and convenience as the parking spaces so
taken, appropriated or condemned (i.e., Landlord using best efforts to locate
the replacement parking spaces as close to the Building as possible). Any of
such Replacement Parking shall be constructed by Landlord within a reasonable
time period following the effective date of such destruction, taking,
appropriation or condemnation, but in no event later than thirty (30) days after
the occurrence of such destruction, taking, appropriation or condemnation, it
being agreed by Landlord and Tenant that such time period shall be extended to
include weather-related delays as aforesaid, in which event such Replacement
Parking will be completed as reasonably possible thereafter, Landlord agreeing
to proceed promptly and with due diligence to complete construction of any
Replacement Parking. Landlord and Tenant acknowledge that if Landlord is
prevented from performing the final paving for said Replacement Parking on
account of weather, such final paving may be performed as soon thereafter as is
feasible. Such notice shall be accompanied by (A) a site plan showing (i) the
location of the Replacement Parking spaces, and (B) an opinion from counsel for
Landlord that such Replacement Parking may be constructed as-of-right under then
applicable zoning and land use regulations.

                                       40
<PAGE>   44

     In the event of any other taking of the Premises, or any part thereof, for
temporary use or for less than one (1) year, (i) this Lease shall be and remain
unaffected thereby; and (ii) Landlord shall pay to Tenant its pro rata share of
any such use, provided that if any taking is for a period extending beyond the
Term of this Lease, such award shall be appointed between Landlord and Tenant as
of the Term Expiration Date.

     Tenant has the option but not the obligation, in any fire or other casualty
which creates a Landlord repair obligation in accordance with the terms of this
Section to make available for such reconstruction all or a portion of the amount
by which the cost of repair as certified by Landlord's architect exceeds the
amount of proceeds received by Landlord.

7.2  RESERVATION OF AWARD

     Landlord reserves to itself any and all rights to receive awards made for
damages to the Premises or Lot and the leasehold hereby created, or any one or
more of them, accruing by reason of exercise of eminent domain or by reason of
anything lawfully done in pursuance of public or other authority. Tenant hereby
releases and assigns to Landlord all Tenant's rights to such awards, and
covenants to deliver such further assignments and assurances thereof as Landlord
may from time to time request. It is agreed and understood, however, that
Landlord does not reserve to itself, and Tenant does not assign to Landlord, any
damages payable for (i) movable trade fixtures installed by Tenant or anybody
claiming under Tenant, at its own expense, or (ii) relocation expenses
recoverable by Tenant from such authority in a separate action, or (iii) the
value of Tenant's improvements installed in the Premises by or on behalf of
Tenant, but not by Landlord.

7.3  ADDITIONAL CASUALTY PROVISIONS

     (a)  Landlord shall not be required to repair or replace any of Tenant's
business machinery, equipment, cabinet work, furniture, personal property or
other installations not originally installed by Landlord.

     (b)  In the event of any termination of this Lease pursuant to this Article
VII, the Term of this Lease shall expire as of the effective termination date as
fully and completely as if such date were the date herein originally scheduled
as the Term Expiration Date, and Landlord shall assist Tenant to the extent
necessary to secure Tenant's share of any insurance award relative to the
Tenant's Work hereunder. Tenant shall have access to the Premises at Tenant's
sole risk for a period of thirty (30) days after the date of termination in
order to remove Tenant's personal property except as prohibited by any
applicable governmental agency or official.

     (c)  Notwithstanding any language to the contrary contained in this Article
VII, if all or any substantial part of the Premises and/or the Building Parking
Areas or any part thereof (as hereinabove defined), shall be damaged by fire or
other casualty or taken by eminent domain during the last two (2) years of the
Term of this Lease or the last two (2) years of either of the Extended Terms, as
the case may be, then either Landlord or Tenant may terminate this Lease
effective as of the date of such fire or other casualty or taking upon notice to
the other as

                                       41
<PAGE>   45

aforesaid, except that Tenant may render Landlord's notice of termination
nugatory by exercising early its option to extend the initial Term, or the
applicable Extended Term, as the case may be, of this Lease for five (5)
additional years in accordance with Exhibit F. In the event of such early
exercise, Landlord and Tenant agree to determine the Fixed Rent for the
applicable Extended Term at least nine (9) months prior to the commencement date
of the applicable Extended Term in accordance with and in the manner set forth
in said Exhibit F.

                                  ARTICLE VIII
                               RIGHTS OF MORTGAGEE

8.1  PRIORITY OF LEASE

     Landlord shall have the option to subordinate this Lease to any mortgagee
or deed of trust of the Lot or Premises, or both ("the mortgaged premises"),
provided that the holder thereof enters into a Subordination, Non-Disturbance
and Attornment Agreement substantially in the form attached hereto as Exhibit J
(or such other form mutually agreeable to Landlord, Tenant and Landlord's
mortgagee, each party agreeing to reasonably cooperate with each other in
reaching mutual agreement on the content of any such other form, so long as such
other form does not substantially reduce or alter Tenant's rights or obligations
thereunder).

8.2  LIMITATION ON MORTGAGEE'S LIABILITY

     Upon entry and taking possession of the mortgaged premises for any purpose
other than foreclosure, the holder of a mortgage shall have all rights of
Landlord, and during the period of such possession, the duty to perform all
Landlord's obligations hereunder. Except during such period of possession, no
such holder shall be liable, either as mortgagee or as holder of a collateral
assignment of this Lease, to perform, or be liable in damages for failure to
perform any of the obligations of Landlord unless and until such holder shall
enter and take possession of the mortgaged premises for the purpose of
foreclosing a mortgage. Upon entry for the purpose of foreclosing a mortgage,
such holder shall be liable to perform all of the obligations of Landlord,
subject to the provisions of Section 8.3 provided that a discontinuance of any
foreclosure proceeding shall be deemed a conveyance under the provisions of
Section 10.4 to the owner of the equity of the mortgaged premises. From and
after making entry and taking possession of the Premises, any such mortgagee
shall be fully and completely liable for the obligations hereunder.

8.3  MORTGAGEE'S ELECTION

     Intentionally Deleted.

8.4  NO PREPAYMENT OR MODIFICATION, ETC.

     No Fixed Rent, additional rent, or any other charge shall be paid more than
thirty (30) days prior to the due dates thereof, and payments made in violation
of this provision shall (except to the extent that such payments are actually
received by a mortgagee in possession or in the process of foreclosing its
mortgage) be a nullity as against such mortgagee. No assignment of

                                       42
<PAGE>   46

this Lease (excepting only in accordance with the provisions of this Lease) and
no agreement to make or accept any surrender, termination or cancellation of
this Lease (excepting only in accordance with the provisions of this Lease) and
no agreement to modify so as to reduce the rent, change the Term, or otherwise
materially change the rights of Landlord under this Lease, or to relieve Tenant
of any obligations or liability under this Lease, shall be valid unless
consented to in writing by Landlord's mortgagees of which Tenant has received
notice.

8.5  NO RELEASE OR TERMINATION

     No act or failure to act on the part of Landlord which would entitle Tenant
under the terms of this Lease, or by law, to be relieved of Tenant's obligations
hereunder or to terminate this Lease, shall result in a release or termination
of such obligations or a termination of this Lease unless (i) Tenant shall have
first given thirty (30) days prior written notice of Landlord's act or failure
to act to Landlord's mortgagees of which Landlord has provided written notice to
Tenant, if any, specifying the act or failure to act on the part of Landlord
which could or would give basis to Tenant's rights, and (ii) such mortgagees,
after receipt of such notice, have failed or refused to correct or cure the
condition complained of within a reasonable time thereafter, but nothing
contained in this Section 8.5 shall be deemed to impose any obligation on any
such mortgagee to correct or cure any such condition. "Reasonable time" as used
above means and includes a reasonable time to obtain possession of the mortgaged
premises, if the mortgagee elects to do so, and a reasonable time to correct or
cure the condition if such condition is determined to exist, however, in no
event shall such time extend beyond sixty (60) days from the date Tenant
provides notice to Landlord's mortgagee(s) as aforesaid.

8.6  CONTINUING OFFER

     The covenants and agreements contained in this Lease with respect to the
rights, powers and benefits of a mortgagee (particularly, without limitation
thereby, the covenants and agreements contained in this Article VIII) constitute
a continuing offer to any person, corporation or other entity, which by
accepting or requiring an assignment of this Lease or by entry or foreclosure
assumes the obligations herein set forth with respect to such mortgagee, and
such mortgagee shall be entitled to enforce such provisions in its own name.
Tenant agrees on request of Landlord to execute and deliver from time to time
any agreement which may reasonably be deemed necessary to implement the
provisions of this Article VIII.

8.7  SUBMITTAL OF FINANCIAL STATEMENT

     At any time, but not more than annually during the Term of this Lease, and
only to the extent Tenant becomes a publicly traded company, within fifteen (15)
days after request therefor by Landlord (i.e. if requested by Landlord'
mortgagee(s)), Tenant shall supply to Landlord and/or any mortgagee of Landlord
a current financial statement, which such financial statement may be given by
Tenant to Landlord in the form of Tenant's current annual report, or such other
financial information as may be reasonably required by any such party. Landlord
agrees to use diligent efforts to keep such information confidential and to
request Landlord's mortgagee to keep such information confidential.

                                       43
<PAGE>   47

                                   ARTICLE IX
                                     DEFAULT

9.1  EVENTS OF DEFAULT BY TENANT

     It shall be an Event of Default under this Lease, if (i) Tenant fails to
pay Fixed Rent or additional rent for more than ten (10) days, after notice
thereof specifying such failure and that such failure may be an Event of Default
hereunder; (ii) Tenant fails to perform its other non-monetary obligations
hereunder for more than thirty (30) days after notice thereof from Landlord,
together with such additional time, if any, as is reasonably required to cure
the default if the default is of such a nature that it cannot reasonably be
cured in thirty (30) days; or (iii) if Tenant makes any assignment for the
benefit of creditors, or files a petition under any bankruptcy or insolvency
law; or (iv) if such a petition is filed against Tenant and is not dismissed
within sixty (60) days; or (v) if a receiver becomes entitled to Tenant's
leasehold hereunder and it is not returned to Tenant within ninety (90) days; or
(vi) such leasehold is taken on execution or other process of law in any action
against Tenant; then, and in any such cases, Landlord and the agents and
servants of Landlord may, in addition to and not in derogation of any remedies
for any preceding breach of covenant, immediately or at any time thereafter
while such default continues and without further notice, enter into and upon the
Premises or any part thereof in the name of the whole or mail a notice of
termination addressed to Tenant at the Premises and repossess the same as of
Landlord's former estate and expel Tenant and those claiming through or under
Tenant and remove its and their effects without being deemed guilty of any
manner of trespass and without prejudice to any remedies which might otherwise
be used for arrears of rent or prior breach of covenant, and upon such entry or
mailing as aforesaid, this Lease shall terminate, but Tenant shall remain liable
as hereinafter provided. After the occurrence of an Event of Default as
aforesaid, Tenant hereby waives all statutory rights of redemption, if any to
the extent such rights may be lawfully waived, and Landlord, without notice to
Tenant, may store Tenant's effects and those of any person claiming through or
under Tenant at the expense and risk of Tenant and, if Landlord so elects, may
sell such effects at public auction or private sale and apply the net proceeds
to the payment of all sums due to Landlord from Tenant, if any, and pay over the
balance, if any, to Tenant.

9.2  TENANT'S OBLIGATIONS AFTER TERMINATION

     In the event that this Lease is terminated under any of the provisions
contained in Section 9.1, Tenant covenants to pay forthwith to Landlord, as
compensation, a single lump-sum payment equal to the excess of the net present
value of the total rent reserved for the residue of the Term (exclusive of any
unexercised Extended Term(s) remaining at the time of termination) over the fair
market rental value of the Premises (including additional rent) for said residue
of the Term estimated as of the date of termination. If Landlord does not
receive a single lump-sum payment from Tenant as aforesaid, Tenant covenants and
agrees to pay punctually to Landlord all the sums and perform all the
obligations which Tenant covenants in this Lease to pay and to perform in the
same manner and to the same extent and at the same time as if this Lease had not
been terminated. In calculating the amounts to be paid by Tenant under the
foregoing covenants,

                                       44
<PAGE>   48

Tenant shall be credited with any amount paid to Landlord as compensation as
provided in the first sentence of this Section 9.2 and also with the net
proceeds of any rents obtained by Landlord by reletting the Premises, after
deducting all Landlord's expenses in connection with such reletting, including,
without implied limitation, all repossession costs, brokerage commissions,
reasonable fees for legal services and reasonable expense of preparing the
Premises for such reletting, it being agreed by Tenant that Landlord may (i)
relet the Premises or any part or parts thereof for a term or terms which may,
at Landlord's option, be equal to or less than or exceed the period which would
otherwise have constituted the balance of the Term and may grant such
concessions and free rent as Landlord in its sole judgment considers advisable
or necessary to relet the same, and (ii) make such alterations, repairs and
decorations in the Premises as Landlord in its sole judgment considers advisable
or necessary to relet the same, and no action of Landlord in accordance with the
foregoing on failure to relet or to collect rent under reletting shall operate
or be construed to release or reduce Tenant's liability as aforesaid. Landlord
hereby agrees in all events to use reasonable efforts and due diligence to
mitigate the foregoing damages and to relet the Premises.

     Nothing contained in this Lease shall, however, limit or prejudice the
right of Landlord to prove and obtain in proceedings for bankruptcy or
insolvency by reason of the termination of this Lease, an amount equal to the
maximum allowed by any statute or rule of law in effect at the time when, and
governing the proceedings in which, the damages are to be proved, whether or not
the amount be greater, equal to, or less than the amount of the loss or damages
referred to above.

                                    ARTICLE X
                                  MISCELLANEOUS

10.1 TITLES

     The titles of the Articles are for convenience and are not to be considered
in construing this Lease.

10.2 NOTICE OF LEASE

     Concurrently with the executing of this Lease, Landlord and Tenant have
executed and recorded a notice of lease in the form attached hereto as Exhibit
T. If this Lease is terminated before the Term expires the parties will execute
an instrument in such form acknowledging the date of termination.

10.3 NOTICES FROM ONE PARTY TO THE OTHER

     No notice, approval, consent requested or election required or permitted to
be given or made pursuant to this Lease shall be effective unless the same is in
writing. Communications shall be addressed, if to Landlord, at Landlord's
Address with a copy to Paul A. Hedstrom, Esq., Hinckley, Allen & Snyder LLP, 28
State Street, Boston, Massachusetts 02109, or at such other address as may have
been specified by prior notice to Tenant and, if to Tenant, at Tenant's

                                       45
<PAGE>   49

Address with a copy to Diane M. McDermott, Esq., Gadsby & Hannah, LLP, 225
Franklin Street, Boston, Massachusetts 02110 and to Suzanne M. Zabitchuck, Esq.,
c/o Siemens Corporation, 200 Wheeler Road, Burlington, Massachusetts 01803 or at
such other place as may have been specified by prior notice to Landlord. Any
communication so addressed shall be deemed duly served if actually received or
delivery is refused at the foregoing addresses mailed by registered or certified
mail, return receipt requested, delivered by hand, or by overnight express
service by a carrier providing a receipt of delivery.

10.4 BIND AND INURE

     The obligations of this Lease shall run with the land, and this Lease shall
be binding upon and inure to the benefit of the parties hereto and their
respective heirs, successors and assigns, except that the Landlord named herein
and each successive owner of the Premises shall be liable only for the
obligations accruing during the period of its ownership, said liability
terminating as to future liability upon termination of such ownership and
passing to the successor in ownership. Neither the Landlord named herein nor any
successive owner of the Premises whether an individual, trust, a corporation or
otherwise shall have any personal liability beyond their equity interest in the
Premises.

10.5 NO SURRENDER

     The delivery of keys to any employees of Landlord or to Landlord's agent or
any employee thereof shall not operate as a termination of this Lease or a
surrender of the Premises.

10.6 NO WAIVER, ETC.

     The failure of Landlord or of Tenant to seek redress for violation of, or
to insist upon the strict performance of any covenant or condition of this Lease
or, with respect to such failure of Landlord, any of the Rules and Regulations
or Park Covenants referred to in Section 6.1.4, whether heretofore or hereafter
adopted by Landlord, shall not be deemed a waiver of such violation nor prevent
a subsequent act, which would have originally constituted a violation, from
having all the force and effect of an original violation, nor shall the failure
of Landlord to enforce any of said Rules and Regulations or Park Covenants
against any other tenant in the Park be deemed a waiver of any such Rules or
Regulations or Park Covenants, as applicable. The receipt by Landlord of Fixed
Rent or additional rent with knowledge of the breach of any covenant of this
Lease shall not be deemed a waiver of such breach by Landlord, unless such
waiver shall be in writing signed by Landlord. No consent or waiver, express or
implied, by Landlord or Tenant to or of any breach of any agreement or duty
shall be construed as a waiver or consent to or of any other breach of the same
agreement or duty in a previous or subsequent instance, or any other agreement
or duty.

10.7 NO ACCORD AND SATISFACTION

     No acceptance by Landlord of a lesser sum than the Fixed Rent and
additional rent then due shall be deemed to be other than on account of the
earliest installment of such rent due, nor

                                       46
<PAGE>   50

shall any endorsement or statement on any check or any letter accompanying any
check or payment as rent be deemed as accord and satisfaction, and Landlord may
accept such check or payment without prejudice to Landlord's right to recover
the balance of such installment or pursue any other remedy in this Lease
provided.

10.8 CUMULATIVE REMEDIES

     The specific remedies to which Landlord may resort under the terms of this
Lease are cumulative and are not intended to be exclusive of any other remedies
or means of redress to which it may be lawfully entitled in case of any breach
or threatened breach by Tenant of any provisions of this Lease. In addition to
the other remedies provided in this Lease, Landlord shall be entitled to the
restraint by injunction of the violation or attempted or threatened violation of
any of the covenants, conditions or provisions of this Lease or to a decree
compelling specific performance of any such covenants, conditions or provisions.

10.9 PARTIAL INVALIDITY

     If any term of this Lease, or the application thereof to any person or
circumstances shall to any extent be invalid or unenforceable, the remainder of
this Lease, or the application of such term to persons or circumstances other
than those as to which it is invalid or unenforceable, shall not be affected
thereby, and each term of this Lease shall be valid and enforceable to the
fullest extent permitted by law.

10.10 RIGHT TO CURE

     (a)  If Tenant shall at any time fail to perform its obligation in
accordance with the provisions of this Lease and Tenant does not commence the
cure of such failure within thirty (30) days of notice thereof (except in the
event of emergencies), and thereafter diligently prosecute such cure to
completion, then Landlord shall have the right, but shall not be obligated, to
enter upon the Premises and to perform such obligation, notwithstanding the fact
that no specific provision for such substituted performance by Landlord is made
in this Lease with respect to such default. In performing such obligation,
Landlord may make any payment of money or perform any other act. All sums so
paid by Landlord (together with interest at the rate set forth in Section 4.3
hereof), and all necessary incidental reasonable third party costs and expenses
in connection with the performance of any such acts by Landlord, shall be deemed
to be additional rent under this Lease and shall be payable to Landlord
immediately on demand. Landlord may exercise the foregoing rights without
waiving any other of its rights or releasing Tenant from any of its obligations
under this Lease.

     (b)  If Landlord shall have failed to perform any of Landlord's covenants
hereunder relating to the Premises (Landlord and Tenant hereby agreeing,
however, that, except as otherwise provided in Section 3.2 relating to Tenant's
right to complete the Punch List Work for its own behalf if Landlord fails to do
so, Tenant shall have no self-help rights with respect to any (i) common areas
or facilities of the Building or any other tenant's space in the Building, if

                                       47
<PAGE>   51

applicable, upon any such expansion of the Building pursuant to Exhibit R
hereof, or (ii) the Building Parking Area, the Lot or the Common Areas of the
Park) within the time periods set forth herein and Landlord does not commence
the cure of such failure within thirty (30) days of notice thereof (except in
the event of emergencies), and thereafter diligently prosecute such cure to
completion, then Tenant shall have the right, but not the obligation, to cure
any such covenants for the account of Landlord. If Tenant shall undertake such
performance, Landlord shall reimburse Tenant for all costs and expenses
reasonably incurred by Tenant in connection with such performance within twenty
(20) days after receipt of an invoice therefor from Tenant (together with any
such back up documentation reasonably requested by Landlord). If Landlord fails
to reimburse Tenant within said twenty (20) day period, then interest at the
rate set forth in Section 4.3 hereof, shall accrue on any amounts due from
Landlord hereunder until such costs have been reimbursed in full. If there
remains any amounts unpaid by Landlord to Tenant hereunder after interest has
commenced to accrue for at least thirty (30) days, then Tenant shall be entitled
to offset the unreimbursed costs together with interest thereon as aforesaid,
against fifteen percent (15%) of the monthly Fixed Rent due hereunder until such
costs due to Tenant hereunder have been reimbursed in full.

10.11 ESTOPPEL CERTIFICATE

     Tenant agrees on the Commencement Date, and from time to time thereafter,
upon not less than thirty (30) days' prior written request by Landlord, to
execute, acknowledge and deliver to Landlord a statement in writing in
substantially the form attached hereto as Exhibit G, certifying if true (and
where not true, indicating where not true), as follows: that this Lease is
unmodified and in full force and effect; that except as set forth in this Lease,
Tenant has no defenses, offsets or counterclaims against its obligations to pay
the Fixed Rent and additional rent and to perform its other covenants under this
Lease; that there are no uncured defaults of Landlord or Tenant under this Lease
(or, if there are any defenses, offsets, counterclaims, or defaults, setting
them forth in reasonable detail); and the dates to which the Fixed Rent,
additional rent and other charges have been paid. Any such statements delivered
pursuant to this Section 10.11 may be relied upon by any prospective purchaser
or mortgage of premises which include the Premises or any prospective assignee
of any such mortgagee.

10.12 WAIVER OF SUBROGATION

     Landlord and Tenant mutually agree, with respect to any hazard which is
covered by casualty or property insurance then being carried by them, or
required to be carried hereunder (whether or not such insurance is then in
effect) to release each other from any and all claims with respect to such loss;
and they further mutually agree that their respective insurance companies shall
have no right of subrogation against the other on account thereof. If extra
premium is payable by either party as a result of this provision, the other
party shall reimburse the party paying such premium the amount of such extra
premium. The parties further agree that if said waiver of subrogation shall be
unobtainable or unenforceable or shall void the respective policies, then their
respective insurance policies shall not be invalidated, and said waiver shall
become null and void and of no further force and effect.

                                       48
<PAGE>   52

10.13 BROKERAGE

     Tenant represents and warrants to Landlord, and Landlord represents and
warrants to Tenant, that it has dealt with no broker, other than such brokers
listed in Section 1.1, in connection with this transaction and agrees to defend,
indemnify and save the other party harmless from and against any and all claims
for a commission arising out of this Lease made by anyone, other than such
brokers in Section 1.1. Landlord shall be responsible for, and hold Tenant
harmless with respect to, all fees and commissions payable to such brokers
specified in Section 1.1.

10.14 PARKING/TRAFFIC PERSONNEL

     Tenant's occupancy of the Premises shall include the use of four (4)
parking spaces per 1,000 square feet of rentable floor area of the Premises.
Tenant's parking spaces shall be known and referred to in this Lease as the
"Building Parking Area" (excluding any Expansion Space as may be hereinafter
included pursuant to Exhibit R), and shall be shown as such on the Landlord's
Plans. The Building Parking Area shall be used by Tenant in common with other
tenants of the Building (which may be expanded pursuant to Exhibit R hereto), if
applicable. Tenant hereby acknowledges that the initial Building Parking Area
includes seventy-two (72) additional spaces not required to be provided to
Tenant pursuant to this Lease. In the event that the Expansion Space is
constructed by Landlord pursuant to the provisions of Exhibit R, then, subject
to the provisions of Exhibit R, the Building Parking Area shall (i) be relocated
to an area designated by Landlord within the cross-hatched parking area (or
expanded in such area(s)) as shown on Exhibit A attached hereto, Tenant hereby
agreeing that such relocation area designated by Landlord on said Exhibit A is
acceptable to Tenant, and (ii) be increased by two hundred twenty-two (222)
parking spaces. However, in the event that the Expansion Space is not
constructed by Landlord, on Tenant's behalf, then Landlord reserves the right to
reduce the initial Building Parking Area shown on Exhibit A by said seventy-two
(72) spaces, or to grant an exclusive easement of such seventy-two (72) spaces
to an affiliate of Landlord, if necessary for Landlord's future development and
operation of the Park, Landlord and Tenant hereby acknowledging and agreeing to
work together, each acting reasonably and in good faith to identify the
seventy-two (72) spaces at such time, if applicable. In no event, however, shall
the foregoing reduce Landlord's obligation to provide Tenant with the use of
four (4) parking spaces per 1,000 square feet of rentable floor area of the
Premises as aforesaid.

     Upon Tenant giving Landlord at least SIXTY (60) days prior written notice,
Landlord agrees to provide traffic control personnel at peak hours, subject to
approval of the Massachusetts Highway Department and the Town of Westford, and
the cost thereof shall be reimbursable to Landlord pursuant to Sections 4.2 and
5.1.2 hereof.

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<PAGE>   53

10.15 ACCESS

     Subject to the terms and provisions of this Lease, Tenant shall have
twenty-four (24) hours, seven (7) days per week, access to the Premises.

10.16 ENTIRE AGREEMENT

     This instrument contains the entire and only agreement between the parties
as to the Premises, and no oral statements or representations or prior written
matter not contained in this instrument shall have any force or effect. This
Lease shall not be modified in any way except by a writing subscribed by both
parties.

10.17 GOVERNING LAW

     This Lease shall be governed by and construed and enforced in accordance
with the laws and courts of the Commonwealth of Massachusetts.

10.18 ADDITIONAL REPRESENTATIONS

     Landlord represents and warrants to Tenant as follows:

     (a)  that Landlord has the right and authority to enter into this Lease and
grant Tenant possession of the Premises and other rights set forth herein;

     (b)  that Landlord is the fee simple owner of the Lot and that Landlord (or
its affiliate(s) or an affiliate(s) of The Gutierrez Company) are the fee simple
owners of the Park; and

     (c)  that the Building (including all common areas, entrances, restrooms,
elevators, water fountains and signage), the Building Parking Area and the Lot
will, upon Substantial Completion and issuance of all necessary permits and
approvals required to be obtained from any and all necessary governmental
agencies prior to occupancy of the Premises by Tenant, including without
limitation, a certificate of occupancy from the Town of Westford which allows
Tenant to use and occupy the Building as specified in Article III hereof, comply
with all dimensional, use, parking, loading and other zoning requirements of the
Town of Westford, and all applicable building codes and governmental
requirements, including without limitation the regulations of the Americans with
Disabilities Act (ADA), and the Park Covenants attached hereto as Exhibit I.

10.19 ROOFTOP COMMUNICATION EQUIPMENT

     Subject to the provisions hereinafter provided, Tenant shall have the right
from time to time during the Term hereof to install rooftop communication
equipment (i.e. satellite or antenna devices) on the roof of the Building.
Subject to applicable law, matters of title, and the consent of Landlord (which
consent shall not be unreasonably withheld or delayed), Tenant, at its sole cost
and expense, has the right to install such equipment on the roof of the
Building. The size

                                       50
<PAGE>   54

and location of the installation shall be at a site acceptable to Landlord, and
the approval of any such size and location shall not be unreasonably withheld or
delayed by Landlord. Tenant shall install the equipment in accordance with sound
construction practices, and in accordance with all applicable laws, rules, codes
and ordinances, and in a good and workmanlike manner. Tenant shall use such
roofing contractor required to comply with the existing roof warranties, as
designated by Landlord. Tenant shall indemnify, defend and hold Landlord
harmless from and against any and all liability or loss arising from or out of
the installation or removal of such rooftop communication equipment. Upon
expiration of the Term, Tenant shall be responsible for the removal of the same
and for repairing any damage caused therefrom.

     IN WITNESS WHEREOF, the parties hereto have duly executed this Lease as of
this __ day of March, 2000.

                                         LANDLORD:
                                         MICHELSON FARM-WESTFORD
                                         TECHNOLOGY PARK TRUST

                                         By: /s/ Arthur J. Gutierrez
                                             -----------------------------------
                                                  __________________, Class A
                                                  Trustee of Michelson
                                                  Farm-Westford Technology Park
                                                  Trust, on behalf of himself
                                                  and his co-Class A Trustee in
                                                  their capacities as said
                                                  trustees and not individually

                                         Dated: 3/30/00
                                                --------------------------------

                                         By:
                                             -----------------------------------
                                                  __________________, Class B
                                                  Trustee of Michelson
                                                  Farm-Westford Technology Park
                                                  Trust, on behalf of himself
                                                  and his co-Class B Trustee in
                                                  their capacities as said
                                                  trustees and not individually

                                         Dated:
                                                --------------------------------

                                       51
<PAGE>   55

and location of the installation shall be at a site acceptable to Landlord, and
the approval of any such size and location shall not be unreasonably withheld or
delayed by Landlord. Tenant shall install the equipment in accordance with sound
construction practices, and in accordance with all applicable laws, rules, codes
and ordinances, and in a good and workmanlike manner. Tenant shall use such
roofing contractor required to comply with the existing roof warranties, as
designated by Landlord. Tenant shall indemnify, defend and hold Landlord
harmless from and against any and all liability or loss arising from or out of
the installation or removal of such rooftop communication equipment. Upon
expiration of the Term, Tenant shall be responsible for the removal of the same
and for repairing any damage caused therefrom.

     IN WITNESS WHEREOF, the parties hereto have duly executed this Lease as of
this __ day of March, 2000.

                                         LANDLORD:
                                         MICHELSON FARM-WESTFORD
                                         TECHNOLOGY PARK TRUST

                                         By: /s/ Arthur J. Gutierrez
                                             -----------------------------------
                                                  __________________, Class A
                                                  Trustee of Michelson
                                                  Farm-Westford Technology Park
                                                  Trust, on behalf of himself
                                                  and his co-Class A Trustee in
                                                  their capacities as said
                                                  trustees and not individually

                                         Dated:
                                                --------------------------------

                                         By: /s/ illegible signature
                                             -----------------------------------
                                                  __________________, Class B
                                                  Trustee of Michelson
                                                  Farm-Westford Technology Park
                                                  Trust, on behalf of himself
                                                  and his co-Class B Trustee in
                                                  their capacities as said
                                                  trustees and not individually

                                         Dated: 3/31/00
                                                --------------------------------

                                       51
<PAGE>   56

                                         TENANT:
                                         UNISPHERE SOLUTIONS, INC.

                                         By: /s/ James A. Dolce, Jr.
                                             -----------------------------------

                                         Its: President
                                              ----------------------------------

                                         Dated: 3/30/00
                                                --------------------------------

                                         AS TO EXHIBIT "R" ONLY:

                                         Michelson Farm-Westford Technology Park
                                         V and VIII Limited Partnership (Current
                                         Owner of a Portion of Lot 10E to be
                                         Created), a Massachusetts Limited
                                         Partnership

                                         By: The Gutierrez Company, sole general
                                             partner

                                             By: /s/ Arthur J. Gutierrez
                                                 ------------------------------
                                                 Arthur J. Gutierrez, President

                                         AS TO EXHIBIT "U" ONLY:

                                         Michelson Farm-Westford Technology Park
                                         IV Limited Partnership (as Owner of
                                         Building 4) and Michelson Farm-Westford
                                         Technology Park VI Limited Partnership
                                         (as Owner of Building 6), both
                                         Massachusetts Limited Partnerships

                                         By: The Gutierrez Company, sole general
                                             partner

                                             By: /s/ Arthur J. Gutierrez
                                                 ------------------------------
                                                 Arthur J. Gutierrez, President

                                       52
<PAGE>   57

                                   EXHIBIT "A"

               PLANS SHOWING TENANT'S SPACE, THE LOT AND THE PARK
                      (INCLUDING THE BUILDING PARKING AREA)

Phase I as shown on Plans entitled A1.1, A1.2 and A1.3, prepared by Symmes,
Maini & McKee Associates, Inc., Sheet C3 "Layout Materials Plan (Phase I)"
prepared by Symmes, Maini & McKee Associates, Inc., and Easement Plan, Sheets 1
- 5, prepared by Howe Surveying for Westford Technology Park, dated June 13,
1996, as revised, and recorded in Plan Book 199, Plan 2.

<PAGE>   58

                                  EXHIBIT "A-1"

                          LEGAL DESCRIPTION OF THE LOT

     A certain parcel of land located on Technology Park Drive in Westford,
Middlesex County, Massachusetts shown as Lot 10D on that certain plan entitled
"Subdivision Plan of Land Technology Park Drive, Westford, Mass." prepared by
Harry R. Feldman, Inc., scale 1" = 100' dated March 3, 2000 and to be recorded
with the Middlesex North Registry of Deeds. Lot 10D contains 11.397 acres
according to said plan (a copy of which is attached hereto and made a part
hereof). Landlord and Tenant hereby acknowledge and agree that this Exhibit A-1
shall be replaced by an amendment to this Lease upon creation of the Lot and the
recording of said plan.

<PAGE>   59
                                EXHIBIT "B-1"

                      Preliminary Base Building Plans

-  Phase I as shown on Plans entitled A1.1, A1.2 and A1.3, prepared by Symmes,
   Maini & McKee Associates, Inc. (Please see plans attached to Exhibit "A")

-  Exterior Elevations Plan A2.1, prepared by Symmes, Maini & McKee Associates,
   Inc.

-  Sheet C3 "Layout & Materials Plan (Phase I)" prepared by Symmes, Maini &
   McKee Associates, Inc. (Please see plan attached to Exhibit "A")

<PAGE>   60

                                  EXHIBIT "B-2"

                        GUTIERREZ CONSTRUCTION CO., INC.

                             OUTLINE SPECIFICATIONS
                                       FOR
                            WESTFORD TECHNOLOGY PARK
                                   BUILDING 10
                             WESTFORD, MASSACHUSETTS

                                 JANUARY 7, 2000
                             REVISED JANUARY 19,2000
                            REVISED FEBRUARY 9, 2000

<PAGE>   61

                             OUTLINE SPECIFICATIONS

                                      INDEX

<TABLE>
<CAPTION>
                                                                                                         PAGE NO.
                                                                                                         --------
<S>                                                                                                      <C>
DIVISION 1 - GENERAL REQUIREMENTS                                                                           3
                   Section 1A - Scope of the Work
                   Section 1B - Assumptions
                   Section 1C - Area Summary

DIVISION 2 - SITE WORK                                                                                      4
                   Section 2A - Site Preparation and Earthwork
                   Section 2B - Site Improvements
                   Section 2C - Lawns and Plantings
                   Section 2D - Site Drainage
                   Section 2E - Site Utilities
                   Section 2F - Irrigation

DIVISION 3 - CONCRETE                                                                                       6
                   Section 3A - Concrete
                   Section 3B - Precast Concrete

DIVISION 5 - METALS                                                                                         7
                   Section 5A - Structural Steel
                   Section 5B - Miscellaneous and Ornamental Iron

DIVISION 6 - CARPENTRY                                                                                      8
                   Section 6A - Rough Carpentry
                   Section 6B - Millwork

DIVISION 7 - MOISTURE PROTECTION                                                                            9
                   Section 7A - Roofing and Flashing
                   Section 7B - Waterproofing, Dampproofing and Caulking

DIVISION 8 - DOORS, WINDOWS AND GLASS                                                                       10
                   Section 8A - Wood Doors
                   Section 8B - Metal Door Frames
                   Section 8C - Finish Hardware
                   Section 8D - Aluminum Entrance
                   Section 8E - Glass and Glazing
                   Section 8F - Overhead Doors
</TABLE>

                                       1
<PAGE>   62

Outline Specifications - Index

<TABLE>
<CAPTION>
<S>                                                                                                         <C>
DIVISION 9 - FINISHES                                                                                       12
                   Section 9A - Resilient Base
                   Section 9B - Acoustical
                   Section 9C - Painting and Vinyl Wallcovering
                   Section 9D - Gypsum Drywall
                   Section 9E - Exterior Soffits
                   Section 9F - Insulation
                   Section 9G - Carpeting
                   Section 9H - Ceramic Tile

DIVISION 10 - SPECIALTIES                                                                                   14
                   Section 10A - Toilet Partitions
                   Section 10B - Toilet Accessories
                   Section 10C - Dock Equipment

DIVISION 12 - FURNISHINGS                                                                                   15
                   Section 12A - Blinds

DIVISION 14 - CONVEYING SYSTEM                                                                              16
                   Section 14A - Elevator

DIVISION 15 - MECHANICAL                                                                                    17
                   Section 15A - Plumbing
                   Section 15B - Heating, Ventilating and Air Conditioning
                   Section 15C - Sprinklers

DIVISION 16 - ELECTRICAL                                                                                    21
                   Section 16A - Electrical Work

DIVISION 17 - EXCLUSIONS                                                                                    23
</TABLE>

                                       2
<PAGE>   63

                                   DIVISION 1

                              GENERAL REQUIREMENTS

SECTION 1A - SCOPE OF THE WORK

1A-01     Gutierrez Construction Co., Inc. will provide all labor, material and
          equipment necessary to complete the construction of the subject
          building in accordance with these Outline Specifications dated
          February 9, 2000, the preliminary drawings as prepared by Symmes,
          Maini & McKee Associates, Inc. dated __________________________, and
          the Site Plan of Land dated ___________________, as prepared by
          Symmes, Maini & McKee Associates, Inc.

SECTION 1B - ASSUMPTIONS

1B-01     All required utilities of adequate size and capacity will be available
          at the property line or in the Subdivision Road immediately adjacent
          to the property line.

1B-02     This proposal is based on Class II-C construction as specified in the
          Massachusetts State Building Code.

SECTION 1C - AREA SUMMARY

1C-01     The building is a three (3) story, "open shell" office building for a
          total of 150,000 square feet.

1C-02     Parking spaces to be provided for four (4) spaces per 1,000 square
          feet of building area.

1C-03     Provide two (2) truck docks and a dumpster pad with a provision to add
          a third truck dock in this building or in the expansion.

                                       3
<PAGE>   64

                                   DIVISION 2

                                    SITE WORK

SECTION 2A - SITE PREPARATION AND EARTH WORK

2A-01    The building site, including landscaped areas, shall be graded to
         "+"0.1' elevations with positive drainage, free of pockets, using
         existing granular materials. All grading is to be done in accordance
         with the site plan developed from the preliminary drawings adjusted so
         as to produce a balanced site.

2A-02    The building pad shall be graded and compacted with six inches (6") of
         suitable granular material to an elevation of minus five inches (-5")
         from finished floor elevation. Compaction shall be 95% proctor method,
         ASTM D 1557.

2A-03    All paved areas shall receive a minimum of eight inches (8") of
         suitable granular material compacted to 92% of its maximum density.

SECTION 2B - SITE IMPROVEMENTS

2B-01    Parking areas shall be paved with two and one half inches (2 1/2") of
         bituminous concrete to consist of one and one-half inches (1 1/2")
         binder coarse and one inch (1") finish. Material and workmanship shall
         be based on State Highway Department specifications.

2B-02    Roads shall be paved as specified for parking areas.

2B-03    Sidewalks shall be paved with four inches (4") of concrete around the
         building and 2 1/2" bituminous paving at parking lots.

2B-04    All necessary curbing shall be granite or bituminous berm as shown on
         the drawings.

SECTION 2C - LAWNS AND PLANTINGS

2C-01    Lawns and planting will be similar to Westford Technology Park Building
         #1.

SECTION 2D - SITE DRAINAGE

2D-01    Parking areas, roadways and trucking areas shall be surface drained and
         underground drainage shall be installed as required.

                                       4
<PAGE>   65

                       DIVISION 2 - SITE WORK (Continued)

SECTION 2E - SITE UTILITIES

2E-01    Domestic water service and fire sprinkler shall be from a water main at
         the property line. The water meter and piping shall be sized to suit
         the building requirements. Fire sprinkler service will be sized per
         NFPA 13 for light hazard.

2E-02    Sanitary sewer shall be connected to the existing Park sewer treatment
         system as indicated on the site plan.

2E-03    Electrical service shall be provided by the electric UTILITY COMPANY'S
         pad-mounted transformer.

2E-04    Telephone service entrance conduit shall be provided as specified by
         the local telephone company.

2E-05    Gas service will be provided by the local utility company.

SECTION 2F - IRRIGATION

2F-01    An automatic, underground lawn irrigation system will be provided for
         all lawn areas adjacent to the building and at the main entrance.

                                       5
<PAGE>   66

                                   DIVISION 3

                                    CONCRETE

SECTION 3A - CONCRETE

3A-01    Provide all plain and reinforced concrete work, including all necessary
         form work, sleeves, inserts, etc. Concrete material shall be 3,000
         p.s.i.

3A-02    Floor slab-on-grade shall be five inch (5") thick concrete reinforced
         with welded wire fabric for a live load rating of 200 p.s.f. Second and
         third floor slabs shall be designed for a load of 100 p.s.f. with live
         load reduction allowed by the Massachusetts State Code.

3A-03    Foundations shall be continuous reinforced concrete footings and walls
         and individual spread reinforced concrete footings under columns. All
         foundations shall bear on engineered fill, natural soil or ledge.

3A-04    Floors shall meet the following level and flatness criteria. Slab on
         grade shall be within FF (flatness) 25 and F1 (level) 20. Suspended
         slabs shall be within FF (flatness) = 20.

SECTION 3B - PRECAST CONCRETE

3B-01    Precast concrete exterior spandrel panels shall be designed to meet
         wind loading as required by the governing code(s) and shall have an
         exposed aggregate finish as approved by the Architect and Owner.

                                       6
<PAGE>   67

                                   DIVISION 5

                                     METALS

SECTION 5A - STRUCTURAL STEEL

5A-01    All structural steel work shall conform to the "Specifications for
         Design, Fabrication and Erection of Structural Steel for Buildings" of
         the American Institute of Steel Construction and the requirements of
         the local building code. All steel shall be ASTM-A-36.

5A-02    The structure shall be steel columns, beams or trusses, and bar joists.
         The building shall be designed in accordance with the building code
         requirements.

5A-03    The roof construction shall be 22 gauge, prime-painted metal roof
         decking. Roof shall be designed to support a live load of 35 p.s.f.
         plus the loading required for a rubber or EPDM ballasted roofing
         system.

5A-04    Second and third floor framing systems shall be designed to support a
         total (live) load of 100 p.s.f. with live load reduction allowed by the
         Massachusetts State Code. Floor decking shall be 28 gauge Fab-Form
         metal deck or equal.

5A-05    Provide thirteen feet (13'-0") from first floor slab to second floor
         slab. Provide thirteen feet (13'-0") from second floor slab to the
         third floor slab. Provide thirteen feet six inches (13'-6") from third
         floor slab to the top of the roof steel.

5A-06    Provide wind framing and attachment for precast concrete.

5A-07    Provide framing and supports for roof top equipment as may be required.

SECTION 5B - MISCELLANEOUS AND ORNAMENTAL IRON

5B-01    Provide manhole and catch basin frames and covers where required.

5B-02    Stairs shall be metal pan, concrete filled type. Stairs shall be
         provided with integral nosings. Handrails shall be tubular steel,
         except as otherwise indicated on the drawings. One stair will service
         the roof.

5B-03    All necessary channel iron supports and hanging rods for toilet
         partitions and glass entrances shall be provided.

5B-04    Provide elevator sill angles.

5B-05    Provide one ornamental stair from the first to the second floor at the
         Atrium.

                                       7
<PAGE>   68

                                   DIVISION 6

                                    CARPENTRY

SECTION 6A - ROUGH CARPENTRY

6A-01    Provide all wood blocking and rough carpentry required.

6A-02    Install wood doors, metal door frames and finish hardware.

6A-03    Install toilet partitions.

SECTION 6B - MILLWORK

6B-01    All men's and women's toilet rooms shall have Corian lavatory counter
         tops with integral bowls, backsplash, endsplash and apron.

6B-03    Provide a four inch (4") oak base at the walls of the lobbies and
         toilet room vestibule areas, or alternate type base as selected.

6B-04    Provide a plastic laminate sill at all perimeter wall office windows.

6B-05    Provide a plastic laminate backsplash at the mop sink in the janitor's
         closet.

                                       8
<PAGE>   69

                                   DIVISION 7

                               MOISTURE PROTECTION

SECTION 7A - ROOFING AND FLASHING

7A-01    The roof shall be insulated to yield a "U" factor of .06. Roof loading
         is to be in accordance with the building code requirements. The roofing
         shall be a ballasted rubber or EDPM roofing system as manufactured by
         Carlysle, Firestone, General Tile or approved equal. A ten (10) year
         labor and material and an additional ten (10) years on material,
         manufacturer's standard guarantee is included.

7A-02    Flashing at the precast concrete parapets and HVAC equipment shall be
         provided.

7A-03    Vent pipe flashings shall be provided as necessary.

SECTION 7B - WATERPROOFING, DAMPPROOFING AND CAULKING

7B-01    Interior caulking shall be the type appropriate for the application.

7B-02    Caulk perimeter of all exterior doors and windows with monolastic,
         meric Thiokol caulking or approved equal.

7B-03    All precast concrete joints shall be caulked with monolastomeric
         Thiokol caulking or approved equal.

7B-04    Waterproof and/or dampproof the elevator pit as required.

                                       9
<PAGE>   70

                                   DIVISION 8

                            DOORS, WINDOWS AND GLASS

SECTION 8A - WOOD DOORS

8A-01    Interior base building wood doors shall be 3'0" x 8'-0" by 1 3/4" solid
         core, plain sliced, red oak and/or 3'0" x 7'0" by 1 3/4" solid core,
         stain grade oak. Provide fire rated doors as required by code. All oak
         doors are to have matching edges.

SECTION 8B - METAL DOORS AND FRAMES

8B-01    All interior base building door frames shall be welded type or three
         piece, pressed metal, single and/or double rabbet door frames with
         proper anchors for partitions. Provide fire rated frames as required by
         code.

SECTION 8C - FINISH HARDWARE

8C-01    Finish hardware shall be heavy duty grade Russwin, Schlage, or approved
         equal.

8C-02    Key schedule shall be per the Owner's requirements.

8C-03    Lockset to have removable cores.

8C-04    Provide electric strikes at exterior doors.

SECTION 8D - ALUMINUM ENTRANCE

8D-01    Aluminum door frame assemblies, including window trim, shall be
         anodized aluminum as indicated on the drawings.

8D-02    Aluminum entrances shall be complete with all hardware (pivot hinges,
         push/pulls, closers, etc.) except cylinder, which is to be furnished
         under Section 8C, Finish Hardware.

8D-03    Provide electric strikes at exterior doors.

SECTION 8E - GLASS AND GLAZING

8E-01    Glass for entrances shall be 1/4" tinted. Entrance doors shall be
         3'0" x 7'O" with glass transom.

8E-02    Mirrors shall be provided over each lavatory at the men's and women's
         toilet rooms. In addition, women's toilet rooms shall be provided with
         a full height mirror located on the wall opposite the lavatories.

8E-03    The exterior glass shall be 7" insulating, tinted as manufactured by
         LOF, PPG or approved equal. Glass area shall be kept under 50% of the
         exterior wall area. Includes Manufacturer's Standard ten (10) year
         warranty for the insulated glass units.

                                       10
<PAGE>   71
               DIVISION 8 - DOORS, WINDOWS AND GLASS (Continued)

SECTION 8E - GLASS & GLAZING (Continued)

8E-04    The aluminum framing for glass shall be anodized aluminum with a
         thermal break as manufactured by Alumiline, Kawneer or approved equal.
         All windows are to be the fixed type.

SECTION 8F - OVERHEAD DOORS

8F-01    Provide two (2) electrically operated, 8' x 8', insulated overhead door
         with weather seal for the truck dock.

                                       11
<PAGE>   72

                                   DIVISION 9

                                    FINISHES

SECTION 9A - RESILIENT BASE FOR THE BASE BUILDING

9A-01    Resilient base shall be 4" high, vinyl cove or straight as applicable.

SECTION 9B - ACOUSTICAL WORK FOR THE BASE BUILDING

9B-01    All base building toilet rooms, stairways and main lobby shall have
         lay-in, reveal edge units of 3/4" x 24" x 24", mineral acoustic tile.
         Suspension system shall be exposed grid "T" suspension system. Ceiling
         height shall be 9'-0", except toilet rooms shall be 7'6". Tile and
         suspension system shall be white.

SECTION 9C - PAINTING FOR THE BASE BUILDING

9C-01    All exposed ferrous metals shall receive a primer coat and one coat of
         enamel.

9C-02    Interior painted walls are to receive two coats of latex paint. The
         lobby will be painted with Zolatone, polymix or approved equal.

9C-03    Interior, base building doors shall receive two coats of semi-gloss
         enamel paint, or one coat of sealer and two coats of polyurethane.

9C-04    Toilet room walls that are not to receive ceramic tile shall be painted
         with Zolatone, polymix or approved equal, or shall receive vinyl wall
         covering at the contractor's option.

SECTION 9D - GYPSUM DRYWALL FOR THE BASE BUILDING

9D-01    Interior, ceiling high partitions shall be 25 ga., 2 1/2" galvanized
         metal studs, 24" O.C. with 5/8" gypsum wallboard on each side, taped,
         sanded and ready for paint. All full-height partitions shall be 25 ga.,
         3 5/8" galvanized metal studs, 24" O.C. with 5/8" gypsum wallboard on
         each side, taped, sanded and ready for paint. Insulation in partitions
         shall be as indicated on the drawings. Provide fire rating as required
         by code. All required fire rated walls shall be constructed with
         approved fire rated drywall assembly systems.

9D-02    The interior of the exterior walls shall be furred with metal studs,
         insulated and covered with drywall in all finished areas. The interior
         face of all precast concrete will be insulated with a minimum of 3 1/2"
         of fiberglass insulation.

                                       12
<PAGE>   73

                       DIVISION 9 - FINISHES (CONTINUED)

SECTION 9D - GYPSUM DRYWALL FOR THE BASE BUILDING (Continued)

9D-03    Interior steel columns will be tubular type, or "H" columns covered
         with drywall, taped, sanded and prepared for finish or exposed tube
         type.

SECTION 9E - EXTERIOR SOFFITS

9E-01    All exposed exterior soffits shall be synthetic plaster.

SECTION 9F - INSULATION

9F-01    Fiberglass blanket type insulation shall be provided behind all
         exterior walls, except behind the spandrel panels where rigid
         insulation may be used.

9F-02    Rigid insulation shall be provided at the perimeter foundation walls.

SECTION 9G - CARPETING

9G-01    An allowance of twenty-four dollars ($24.00) per square yard has been
         included for all carpet at the base building areas.

SECTION 9H - CERAMIC TILE

9H-01    Toilet rooms and showers shall have 1" x 1", unglazed, ceramic floor
         tile and 4 1/4" x 4 1/4" glazed, ceramic tile, full height, at wet
         walls.

                                       13
<PAGE>   74

                                   DIVISION 10

                                   SPECIALTIES

SECTION 10A - TOILET PARTITIONS

10A-01   Partitions shall be ceiling hung with a baked enamel finish. Provide
         toilet partitions as indicated on the drawings.

SECTION 10B - TOILET ACCESSORIES

10B-01   Provide brushed stainless steel accessories as indicated on the
         drawings. Accessories shall include double roll toilet paper holders,
         recessed paper towel dispenser/disposals, liquid soap dispensers,
         sanitary napkin vendors and disposals and grab bars at handicap
         toilets. Also, provide mop hooks at janitor's closets.

SECTION 10C - DOCK EQUIPMENT

10C-01   Provide two (2) mechanical 20,000 pound capacity dock levelers. Dock
         bumper integral with the dock leveler shall be provided. Provide space
         next to truck dock for the compactor. Truck dock will be standard 48"
         height. Also, provide seals and/or shelters, swivel dock lights and
         bollards.

                                       14
<PAGE>   75

                                   DIVISION 12

                                   FURNISHINGS

SECTION 12A - BLINDS

12A-01   Vertical blinds shall be LouverDrape, Model EL (Elite) or approved
         equal, both traversing and rotating types.

12A-02   Blinds shall have top track only with manufacturer's standard baked
         enamel finish.

12A-03   Vertical blind blades are to be PVC solid core, 3 1/2" wide, .03"
         thickness. Color shall be manufacturer's standard color as selected by
         the Owner and Architect.

12A-04   Blinds shall be installed at all exterior wall windows.

                                       15
<PAGE>   76

                                   DIVISION 14

                                CONVEYING SYSTEM

SECTION 14A - ELEVATOR

14A-01    Two (2) standard package, 3,500 pound capacity hydraulic passenger
          elevators shall be provided at the main entrance lobby and one (1)
          standard package 4,500 pound capacity hydraulic passenger/material
          elevator near the truck dock. Speed shall be 125 feet per minute. Cab
          finish shall be stainless steel on front panels and doors, plastic
          laminate walls, and baked enamel frame and entrance doors on hall
          side. Include protective pads and hooks, handrail at rear, telephone
          box and cable, removable ceiling, certificate frame, emergency car
          lighting, exhaust fan, handicapped code requirements and 36" center
          opening doors. Includes an allowance of $20,000.00 to upgrade the
          finishes of the two elevators in the main lobby. Upgrade finishes
          shall be selected from the manufacturer's upgrade finish options.

                                       16
<PAGE>   77

                                   DIVISION 15

                                   MECHANICAL

DIVISION 15A - PLUMBING

15A-01   CODES, ORDINANCES AND PERMITS

         1.   All material and workmanship shall be in strict accordance with
              the following codes:

              A.   MASSACHUSETTS STATE PLUMBING CODE
              B.   MASSACHUSETTS STATE BUILDING CODE
              C.   NATIONAL FIRE CODES
              D.   REQUIREMENTS OF THE TOWN OF WESTFORD, MASSACHUSETTS
              E.   DEPARTMENT OF PUBLIC HEALTH

15A-02   SANITARY WASTE AND VENT SYSTEM
         1.   Interior waste and vent piping shall convey wastes to the
              underground sanitary waste system and shall be vented through the
              roof as required by code.

         2.   Exterior sanitary waste shall be connected to the existing Park
              sewer treatment system as indicated on the site plan.

15A-03   ROOF DRAINAGE SYSTEM
         1.   Interior roof drains shall be adequately sized and installed to
              drain all roof surfaces and shall be connected to the storm drain
              outside the building line.

15A-04   COLD AND HOT WATER-SYSTEMS
         1.   Cold and hot water systems shall be installed to service all
              fixtures and equipment indicated on the drawings requiring cold
              and hot water.

         2.   Cold and hot water shall be sized in accordance with the latest
              requirements of the applicable plumbing code.

         3.   Provide isolation valves at each toilet room by floor.

15A-05   GAS PIPING
         1.   Provide gas piping from the meter to the rooftop HVAC Units.

15A-06   PIPING AND FITTINGS
         1.   Piping and fittings shall be cast iron for sanitary and storm,
              and copper for water - all conforming to the latest ASTM and/or
              F.S. standards.

15A-07   PIPING AND DRAINAGE ACCESSORIES
         1.   Roof drains, wall/ground hydrants, cleanouts, and fixture
              carriers shall be as manufactured by J.R. Smith, Josam, Zurn or
              approved equal. Pressure-reducing valves and back flow preventors
              shall be as manufactured by Watts or approved equal.

                                       17
<PAGE>   78

                      DIVISION 15 - MECHANICAL (CONTINUED)

SECTION 15A - PLUMBING (continued)

15A-08   INSULATION
         1.   All above-ground cold water piping, valves and fittings shall be
              insulated, including the air chamber. Horizontal rain leaders and
              all roof drains shall be insulated.

15A-09   WATER METER
         1.   Water meter and piping shall be furnished and installed in
              accordance with the Town of Westford, Massachusetts'
              requirements.

15A-10   PLUMBING FIXTURES
         1.   Water closets shall be wall-hung, elongated, flush valved closets
              with 1 1/2" top spuds and exposed valves as manufactured by
              Kohler Company or approved equal, with white, open front seats,
              no cover.
         2.   Urinals shall be wall-hung, white with 1 1/2" top spuds, exposed
              valves as manufactured by Kohler Company or approved equal.
         3.   Lavatories shall be drop-in, counter type.
         4.   Drinking fountains (one on each floor) shall be electric,
              semi-recessed, wall-mounted type as manufactured by Halsey Taylor
              or approved equal.
         5.   Electric hot water heater(s), sized to suit the base building
              requirements, shall be provided.
         6.   Handicap type fixtures will be provided in the toilet rooms as
              required by applicable codes.

15A-11   TESTING
         1.   All piping systems shall be tested in accordance with the
              applicable codes.

SECTION 15B - HEATING, VENTILATING AND AIR CONDITIONING

15B-01   Provide rooftop, variable volume, heating, ventilating and air
         conditioning to provide comfort heating and cooling on a year-round
         basis with controlled night set back and economizing features, and
         shall meet all applicable code requirements. Capacity will be based on
         325 S.F./Ton. Equipment shall be as manufactured by Carrier, Trane or
         approved equal as selected by Gutierrez Construction Co., Inc. A low
         voltage, automatic temperature control system will also be provided.
         Include an override switch for each rooftop unit to allow after hours
         operation. Includes HVAC distribution for the base building areas. Does
         not include HVAC distribution at tenant areas. The rooftop HVAC Units
         will provide gas fired morning warm-up to meet the requirements of the
         Massachusetts Energy Code. The rooftop HVAC Units will be provided with
         three feet (3') high vibration/insulated curbs to minimize noise and
         vibration. Rooftop units will not be operated without filters. Filters
         used during construction will be changed prior to Tenant's occupancy.
         The ventilation for the building will be designed per the Massachusetts
         State Code.

                                       18
<PAGE>   79

                      DIVISION 15 - MECHANICAL (CONTINUED)

SECTION 15B - HEATING, VENTILATING AND AIR CONDITIONING (Continued)

15B-02   DUCT WORK

         All duct work shall be galvanized steel to meet the ASHRAE standards.
         Flexible duct run-outs shall not exceed six feet (6').

15B-03   GRILLES AND DIFFUSERS

         As required for the base building.

15B-04   TOILET ROOM EXHAUST

         A toilet room exhaust system shall be installed in accordance with the
         code requirements.

15B-05   NOISE LEVELS

         The HVAC System will be designed to meet or exceed an NCR of 35 to 40.

15B-06   HEATING, VENTILATING AND AIR CONDITIONING FOR TENANT AREAS

         A zoned heating, ventilating and air conditioning system, including
         distribution duct work, diffusers, return air grilles and thermostatic
         control for general office use is not included. Duct shafts and ducts
         will be provided from the rooftop equipment to the first and second
         floors. Above the ceiling will be used as a return air plenum. Return
         ductwork is not anticipated.

SECTION 15C - SPRINKLERS

15C-01   An automatic wet pipe, light hazard sprinkler system shall be provided
         for the base building. System shall be designed to meet the I.S.O. and
         NFPA #13 requirements. Heads at acoustical ceilings shall be chrome
         plated, semi-recessed, pendant type located at the center one third
         (1/3) of the 24" x 24" ceiling tile. Heads in open areas shall be the
         brass upright type. Testing shall be in accordance with NFPA Pamphlet
         No. 13. Furnish and install tamper and flow switches. Wiring shall be
         by the electrical subcontractor. Sprinkler distribution for the tenant
         areas is not included. Stub outs will be provided on each floor.
         Includes standpipe and fire hose cabinets as required.

                                       19
<PAGE>   80

                                   DIVISION 16

                                   ELECTRICAL

SECTION 16A - ELECTRICAL WORK

16A-01   SERVICE ENTRANCE

         The primary electric service and pad mounted transformer will be
         provided by the local utility company at no cost to Gutierrez
         Construction Co., Inc. Provide underground PVC conduit for electric
         and telephone as required by the utility companies. The secondary side
         of the electrical service will be 3,000 Amps at 480 Volt, 3-phase,
         4-wire. Provide empty conduit from the pad mounted transformer to the
         switchgear and design the switchgear so the capacity can be increased
         for the expansion of 75,000 square feet. When the Tenant's additional
         electrical requirements are determined, the main service size, feeder
         circuits and equipment will be increased at the Tenant's cost.

16A-02   CODES AND STANDARDS

         Materials and workmanship shall conform with the latest editions of the
         following applicable codes, standards and specifications:

         1.   National Board of Fire Underwriters
         2.   Underwriter's Laboratories, Inc.
         3.   National Electrical Code
         4.   National Bureau of Standards Handbook 11-30, National Safety Code
         5.   Local and State Building Codes, and all other authorities having
              jurisdiction

16A-03   RACEWAYS AND CONDUCTORS

         Generally, wiring will consist of insulated conductors installed in
         3/4" minimum size, EMT. Flexible conduit (BX) will be used for terminal
         connection at all motors. Electrical metallic tubing will be used in
         areas above hung ceilings. Aluminum conduit may be used in concealed
         areas or in areas eight feet (8') above the floor. No aluminum conduit
         will be used in concrete or underground. BX may be used where allowed
         by applicable codes. Above the ceiling is used as a return air plenum.
         Conductors will be 600 volt copper, except where otherwise noted.
         Wire/cable #2 and larger may be aluminum. The following conductors will
         be used:

         1.   Power:          #12 Minimum 75(0)C THWN
         2.   Lighting:       #12 Minimum 75(0)C THWN
         3.   Control:        #14 Minimum 75(0)C THW
         4.   Fixture:        #16 Minimum 90(0)C MTW
         5.   Alarm:          #14 Minimum 75(0)C THW

                                       20
<PAGE>   81

                      DIVISION 16 - ELECTRICAL (CONTINUED)

SECTION 16A - ELECTRICAL WORK (Continued)

16A-04   GROUNDING SYSTEM

         Grounding will consist of copper clad steel rods connected with bare
         copper cable. The grounding system will be connected to the existing
         ground in the power plant. The interconnection conductors will be built
         into the main feeder cable. Building steel and all electrical equipment
         enclosures will be grounded.

16A-05   FEEDER CIRCUITS

         Feeders will supply 480/277 volt power from the main distributor to
         distribution panels. Main service will be adequately sized to serve the
         building's requirements as specified in these outline specifications.
         The main riser electrical feeder will be by a vertical plug-in type
         busway system. Includes transient voltage surge protection at the
         service entrance and branch circuit panel boards.

16A-06   TRANSFORMERS

         Dry-type K20 rated transformers will be provided for 120/208 volt
         panels.

16A-07   PANELBOARDS

         Panelboards will be 480/277 volt, 3-phase, 4-wire and 120/208 volt,
         3-phase, 4-wire with 200% neutrals with provisions for bolt in circuit
         breakers. Panelboards will be sized for the HVAC 6 watts per square
         foot and 2 watts per square foot for the 277 volt light fixtures and 6
         watts per square foot at for 120/208 volt power. Panelboards will be
         located in electrical closets on each floor.

16A-08   WIRING DEVICES, OUTLETS AND SWITCHES

         1.   Switches will be the quiet toggle type, NEMA standard.
         2.   Convenience outlets will be duplex grounding type, 20 amp rates,
              NEMA standard.
         3.   Device plates will be ivory-colored plastic.

16A-09   INDOOR LIGHTING

         Lighting will be fluorescent and/or incandescent for the base building.
         Lighting in tenant areas is not included.

16A-10   OUTDOOR LIGHTING

         Building lighting will be provided for security lighting and provide
         400 watt, high pressure sodium fixtures, energized at 277/480 volt with
         photocell control and time clock override. High pressure sodium
         fixtures will have integral ballasts. Fixtures will be pole-mounted in
         parking areas. Provide lighting at sidewalks for pedestrians. Lighting
         at the parking areas will be in accordance with the latest energy code
         requirements, but will provide a minimum of 0.5 foot candles at the
         remote parking areas.

                                       21
<PAGE>   82

                      DIVISION 16 - ELECTRICAL (CONTINUED)

SECTION 16A - ELECTRICAL WORK (Continued)

16A-11   EMERGENCY LIGHTING AND POWER SYSTEM

         Provide emergency power for exit lights, emergency lighting and fire
         alarm system. Power source for emergency power shall be wet cell
         batteries located in the electrical rooms or a natural gas fired, roof
         mounted emergency generator as selected by the Landlord. Provide exit
         lights, emergency lights and fire alarm at all common areas as required
         by applicable codes. Exit lights, emergency lights and fire alarm
         distribution at tenant areas are not included.

16A-12   TELEPHONE EQUIPMENT

         Provide eight (8) 4" sleeves at each telephone room (or as designated
         by the Tenant) through the second and third floor slabs.
         Interconnection and telephone equipment will be by the telephone
         company. Telephone interface will be the responsibility of the tenant
         and will be installed in the tenant's space.

16A-13   FIRE ALARM SYSTEM

         A local fully addressable fire alarm system with horn/light
         combinations, pull stations and annunciator panel will be provided for
         the base building. The main fire alarm panel and annunciator panel will
         be sized to accommodate the tenant area. Location of horn/lights, pull
         stations and annunciator panel shall be in accordance with applicable
         codes and the local fire department's requirements. Connect to the
         local fire department if available. Double shielded cable will be used.

                                       22
<PAGE>   83

                                   DIVISION 17

                                   EXCLUSIONS

1.   Power wiring for any special equipment or outlets other than those
     specified in these Outline Specifications.

2.   Special floor finishes, other than those previously mentioned.

3.   Special wall finishes, other than those previously mentioned.

4.   Special millwork items, other than those previously mentioned.

5.   Health Department or other regulatory agency requirements resulting from
     tenant's operations unknown to Gutierrez Construction Co., Inc.

6.   Furniture, furnishings, etc.

7.   Security, intercom or sound system.

8.   Vending machines or provisions for such.

9.   Kitchen equipment.

10.  Moveable partitions.

11.  Special exhaust systems.

12.  Underfloor duct systems.

13.  Drinking fountains, other than those specified.

14.  Drywall partitions, including demising walls and painting for tenant areas.

15.  Doors, frames and hardware for tenant areas.

16.  Vinyl base for tenant areas.

17.  Power distribution, lights, outlets, light switches, exit signs/lights, and
     emergency lights at tenant areas.

18.  Special modifications required for a day care center, if any.

19.  Sprinkler piping and heads at tenant areas.

20.  HVAC air terminal units, duct work, grilles and diffusers at tenant areas.

                                       23
<PAGE>   84

                                 "EXHIBIT C-1"

CERTIFICATE OF                               OWNER          [ ]
SUBSTANTIAL                                  ARCHITECT      [ ]
COMPLETION                                   CONTRACTOR     [ ]
AIA DOCUMENT G704                            FIELD          [ ]
                                             OTHER

--------------------------------------------------------------------------------
PROJECT:                                           ARCHITECT:
(name, address)
                                                   ARCHITECT'S PROJECT NUMBER:

TO (Owner)
                                                   CONTRACTOR:
                                                   CONTRACT FOR:

                                                   CONTRACT DATE:

DATE OF ISSUANCE:

PROJECT OR DESIGNATED AREA SHALL INCLUDE:

The Work performed under this Contract has been reviewed and found to be
substantially complete. The Date of Substantial Completion is hereby established
as which is also the date of commencement of all warranties and guarantees
required by the Contract Documents.

--------------------------------------------------------------------------------
                  DEFINITION OF DATE OF SUBSTANTIAL COMPLETION
                  --------------------------------------------

The date of Substantial Completion of the Work or designated portion thereof is
the Date certified by the Architect when construction is sufficiently complete,
in accordance with the Contract Documents, so the Owner may occupy the Work or
designated portion thereof for the use for which it is intended.
--------------------------------------------------------------------------------

A list of items to be completed or corrected, prepared by the Contractor and
verified and amended by the Architect, is appended hereto. The failure to
include any items on such list does not alter the responsibility of the
Contractor to complete all Work in accordance with the Contract Documents.

___________________________   ___________________________   ____________________
ARCHITECT                     BY                            DATE

The Contractor will complete or correct the Work on the list of items appended
hereto within       days from the above Date of Substantial Completion.

___________________________   ___________________________   ____________________
CONTRACTOR                    BY                            DATE

The Owner accepts the Work or designated portion thereof as substantially
complete and will assume full possession thereof at              (time) on
     (date).

___________________________   ___________________________   ____________________
OWNER                         BY                            DATE

--------------------------------------------------------------------------------
The responsibilities of the Owner and Contractor for maintenance, heat,
utilities and insurance shall be as follows: (NOTE - Owner's and Contractor's
legal and insurance counsel should determine and review insurance requirements
and coverage)

<PAGE>   85

                                  EXHIBIT "C-2"

                         CERTIFICATE OF FINAL COMPLETION

Project:       Unisphere Solutions, Inc.                   Lease Date: ___, 2000

Location:      Technology Park Drive                       Date:
               Westford, Massachusetts

Owner:         Arthur J. Gutierrez and John A. Cataldo,    Trade:
               Class A Trustees, and Howard Stock and
               Marc D. Levy, Class B Trustees, all as
               Trustees of Michelson Farm-Westford
               Technology Park Trust, under Declaration
               of Trust dated October 1, 1984, recorded with
               the Middlesex North District Registry of Deeds
               in Book 2863, Page 235

( )  All work has been completed in accordance with Article III of the Lease.

( )  All work has been completed in accordance with Article III of the Lease,
     except for that listed in attached schedule for which a credit has been
     taken.

Final Inspection was made _________________ in the presence of:

Remarks:

Owner must have completed or corrected all punch list items or accepted credit
for unsatisfactory or incomplete work and submitted all Close-out Documents as
listed on Close-out Documents - Record & Transmittal Form.

This is to certify that Unisphere Solutions, Inc. will not be held responsible
for any bills, liens, claims or demands in connection with the above noted
project. All workmanship and materials are hereby guaranteed in accordance with
stipulations in the Contract Documents and Lease on Certificate of Substantial
Completion.

By:________________________________         By:_________________________________

Title:_____________________________         Title:______________________________

Date:______________________________         Date:_______________________________

NOTE: See also definition of Substantial Completion in Article III of the Lease.

<PAGE>   86

                                   EXHIBIT "D"
                               LANDLORD'S SERVICES

I.   CLEANING

     A.   General

          1.   All cleaning work will be performed between 8:00 AM and midnight,
               Monday through Friday, unless otherwise necessary for stripping,
               waxing, etc.

          2.   Abnormal waste removal (e.g., computer installation paper, bulk
               packaging, wood or cardboard crates, refuse from cafeteria and
               laboratory operations, etc.) shall be Tenant's responsibility.

     B.   Daily Operations (5 times per week)

          1.   Tenant Areas

               a.   Empty and clean all waste receptacles. Wash receptacles as
                    necessary.
               b.   Vacuum all rugs and carpeted areas.
               c.   Empty, damp-wipe and dry all ashtrays.

          2.   Lavatories

               a.   Sweep and wash floors with disinfectant.
               b.   Wash both sides of toilet seats with disinfectant.
               c.   Wash all mirrors, basins, bowls, urinals.
               d.   Spot-clean toilet partitions.
               e.   Empty and disinfect sanitary napkin disposal receptacles.
               f.   Refill toilet tissue, towel, soap and sanitary napkin
                    dispensers.

          3.   Public Areas

               a.   Wipe down entrance doors and clean glass (interior and
                    exterior).
               b.   Vacuum elevator carpets and wipe down doors and walls.

     C.   Operations as Needed (but not less than every other day)

          1.   Tenant and Public Areas

               a.   Buff all resilient floor areas every other day.
               b.   Clean water coolers.

<PAGE>   87

     D.   Weekly Operations

          1.   Tenant Areas, Lavatories, Public Areas

               a.   Hand dust and wipe clean all horizontal surfaces with
                    treated cloths to include furniture, office equipment,
                    window sills, door ledges, chair rails, baseboards,
                    convector tops, etc. within normal reach.
               b.   Remove finger marks from private entrance doors, light
                    switches, and doorways.
               c.   Sweep all stairways.

     E.   Monthly Operations

          1.   Tenant and Public Areas

               a.   Thoroughly vacuum seat cushions on chairs, sofas, etc.
               b.   Vacuum and dust grillwork.

          2.   Lavatories

               a.   Wash down interior walls and toilet partitions.

     F.   As Required and Weather Permitting (but not less than three times per
          year)

          1.   Entire Building

               a.   Clean inside of all windows.
               b.   Clean outside of all windows.

     G.   Yearly

          1.   Tenant and Public Areas

               a.   Strip and wax all resilient tile floor areas.

II.  HEATING, VENTILATING AND AIR CONDITIONING

          1.   Heating, ventilation and air conditioning (HVAC) as required to
               provide reasonably comfortable temperatures for normal business
               day occupancy (except holidays), Monday through Friday, from 8:00
               AM to 6:00 PM and Saturday from 8:00 AM to 1:00 PM. Tenant shall
               be operating HVAC systems beyond the hours specified above and
               any additional maintenance or services associated with such
               overtime use shall be furnished by Landlord provided that the
               additional costs thereof are chargeable to Tenant pursuant to the
               provisions of Sections 4.2 and 5.1.2 Note: Cost of electricity to
               be paid directly by Tenant to utility company.

                                       2
<PAGE>   88

     2.   Maintenance on any additional or special air conditioning equipment
          and the associated operating cost will be at Tenant's expense.

III. WATER

     1.   Prior to the commencement of the Term hereunder, Landlord is
          responsible for providing water up to, but not including, Tenant's
          water meter, such that hot water for lavatory purposes and cold water
          for drinking, lavatory and toilet purposes are available. Thereafter,
          Tenant is responsible for all water and sewer charges consumed in the
          leased premises, as measured by Tenant's water meter.

     2.   The cost of the repair or replacement of a hot water heater which
          supplies hot water exclusively in a sink in Tenant's Premises will be
          the responsibility of Tenant.

IV.  ELEVATORS

     Elevators for the use of all tenants and the general public for access to
     and from all floors of the Building, programming of elevators (including,
     but not limited to, service elevators), shall be as Landlord from time to
     time reasonably determines best for the Building as a whole, Landlord
     hereby agreeing that Tenant may provide input in connection therewith.

V.   RELAMPING OF LIGHT FIXTURES

     Tenant will reimburse Landlord for relamping, ballasts and starters within
     the Premises.

VI.  CAFETERIA, VENDING AND PLUMBING INSTALLATIONS; LABORATORY

     1.   Any space to be used primarily for lunchroom or cafeteria operation
          (currently estimated at 3,000 square feet) shall be Tenant's
          responsibility to keep clean and sanitary, unless otherwise mutually
          agreed upon in writing by Landlord and Tenant. Cafeteria, vending
          machines or refreshment service installations by Tenant must be
          approved by Landlord in writing, Landlord hereby acknowledging and
          agreeing that it shall approve a cafeteria in connection with the
          Tenant's Plans. All maintenance, repairs and additional cleaning
          necessitated by such installations shall be at Tenant's expense.

     2.   Tenant is responsible for the maintenance and repair of plumbing
          fixtures and related equipment installed in the Premises for its
          exclusive use (such as in coffee room, cafeteria, laboratory, or
          employee exercise area, if applicable), and all of such other fixtures
          described as Tenant's Property in Section 6.1.13.

     3.   Any space to be used primarily for laboratory operations (currently
          estimated at 30,000 square feet) shall be Tenant's responsibility to
          keep clean and neat, unless otherwise mutually agreed upon in writing
          by Landlord and Tenant.

                                       3
<PAGE>   89

VII. ELECTRICITY

     1.   Tenant shall pay for all electricity and gas consumed in the Premises
          directly to the respective utility providers.

     2.   Tenant's use of electrical service in the Premises shall not at any
          time exceed the capacity of any of the electrical conductors or other
          equipment in or otherwise serving the Premises or the Building
          standard, as hereinafter provided. To ensure that such capacity is not
          exceeded and to avert possible adverse effects upon the Building's
          electrical system, Tenant shall not, without at least ten (10) days
          prior written notice to and consent of Landlord in each instance,
          connect to the Building electric distribution system any fixtures,
          appliances or equipment which operates on a voltage in excess of 120
          volts nominal, or which requires a single (dedicated) circuit, or make
          any alteration or addition to the electric system of the Premises. In
          the event Tenant shall use (or request that it be allowed to use)
          electrical service in excess of that deemed by Landlord to be standard
          for the Building, Landlord may refuse to provide such excess usage or
          refuse to consent to such usage or may consent upon such conditions as
          Landlord reasonably elects (including but not limited to the
          installation of utility service upgrades, submeters, air handlers or
          cooling units), and all such additional usage (except to the extent
          prohibited by law), installation and maintenance thereof shall be paid
          for by Tenant, as additional rent, upon Landlord's demand.

     3.   It is understood that the electrical service to the Premises may be
          furnished by one or more suppliers of electricity and that the cost of
          electricity may be billed as a single charge or divided into and
          billed in a variety of categories such as distribution charges,
          transmission charges, generation charges, public good charges and
          other similar categories and may also include a reasonable fee,
          commission or other charge by a broker, aggregator or other
          intermediary for obtaining or arranging the supply of electricity.
          Landlord shall, upon Tenant's prior approval (not to be unreasonably
          withheld or delayed) so long as Tenant remains the sole tenant of the
          Building, have the right to select the supplier of electricity to the
          Building, Premises and Lot, and, as Tenant's agent, to designate the
          same to a local utility, to aggregate the supply of electricity for
          the Building, Premises and Lot with other buildings, to purchase
          electricity for the Building, Premises and Lot through a broker,
          aggregator or other intermediary and/or buyers group or other group
          and to change the supplier of electricity and/or manner of purchasing
          electricity from time to time.

          If Landlord undertakes activities for the purpose of reducing
          Landlord's or Tenant's operating costs (such as negotiating an
          agreement with a utility or another energy supplier or engaging an
          energy consultant or undertaking conservation or other energy
          efficient measures that may require capital expenditures), Tenant
          shall pay its proportionate share of all costs and expenses associated
          with such actions (including but not limited to brokers' commissions,
          legal fees and capital expenditures), as additional rent, as and when
          payment is made by Landlord, so long as Tenant's approval has been
          obtained by Landlord in advance, which such approval shall not be
          unreasonably withheld or delayed by Tenant and which such approval of
          Tenant shall only be required so long as Tenant remains the sole
          tenant of the Building.

                                       4
<PAGE>   90

     4.   Utility lines and other facilities that supply the Premises, whenever
          installed, may be the subject of a requirement that the owner of the
          Premises make payments for the lines or other facilities upon the
          occurrence of certain events, if, for example, a tenant utilizing such
          facilities discontinues purchasing energy from the provider of the
          facilities, Landlord may be required to enter into agreements that
          would obligate it to make such payments in the future. Landlord agrees
          to notify the Tenant of any such agreements, any amendments,
          modifications, replacements or substitutions thereto, Landlord hereby
          acknowledging that there are no such agreements currently in force or
          effect. If such payments are required, whether based on contract or
          tariff, from Landlord with respect to such facilities that are
          utilized by the Tenant, the Landlord shall so inform Tenant in
          writing, and the Tenant thereby agrees that it shall reimburse the
          Landlord for its proportionate share of all such payments as
          additional rent, when and as made by the Landlord, with no profit to
          Landlord.

     5.   As used in this Section VII, the term "supplier(s) of electricity"
          shall mean one or more companies (including but not limited to an
          electric utility, generator, independent or non-regulated company or
          intermediary or broker or group) that provides electricity to the
          Premises or to the Landlord to be provided to the Premises, as the
          case may be.

VIII.     SNOW REMOVAL AND LANDSCAPING

          As may be necessary and consistent with the other lots in the Park to
          provide landscaping services and snow removal on the Lot.

                                       5
<PAGE>   91

                                   EXHIBIT "E"
                              RULES AND REGULATIONS

1.   No curtains, blinds, shades, screens, or signs other than those furnished
     by Landlord shall be attached to, hung in, or used in connection with any
     window or door of the Premises without the prior written consent of the
     Landlord. All interior Tenant signage is at Tenant's expense and must be
     installed or affixed by a contractor first approved by Landlord acting
     reasonably and without delay. The style, size and color of any interior
     signage visible from the exterior of the Premises must also be reasonably
     acceptable to Landlord.

2.   As well as any security (door access) system provided and installed by
     Tenant, as reasonably approved by Landlord, Tenant shall be allowed to
     place additional locks or bolts upon doors and windows within the Premises.
     Tenant recognizes that these additional locks and bolts could prove to be a
     hindrance to Landlord providing building services such as cleaning and
     maintenance. Tenant must, upon the termination of its tenancy and provide
     Landlord all Building access cards and keys either furnished to or
     otherwise procured by Tenant; and in the event of the loss of any keys so
     furnished, Tenant shall pay to Landlord the reasonable cost thereof.

3.   Canvassing, soliciting and peddling in the Building are prohibited, and
     Tenant shall cooperate to prevent the same.

4.   Tenant shall comply with all reasonably necessary security measures from
     time to time established by Landlord for the Park.

5.   Tenant agrees that there shall be no smoking allowed anywhere in the
     Building.

6.   Tenant shall comply with the Park Covenants attached hereto as Exhibit "I",
     provided that such compliance is within Tenant's control, Landlord hereby
     acknowledging and agreeing, as set forth in Section 10.18, that Landlord's
     construction of the Landlord's Work and Tenant's Work shall be in
     compliance therewith.

<PAGE>   92

                                   EXHIBIT "F"
                                OPTION TO EXTEND

     The Tenant has the option to extend this Lease for two (2) successive five
(5) year terms ("Extended Terms", and separately the "First Extended Term" and
the "Second Extended Term"), the exercise of each of which shall automatically
extend the term of this Lease without the necessity of additional documentation.
So long as there does not exist any Event of Default hereunder at such time, and
except as otherwise set forth in Article VII of this Lease, the option to extend
shall be deemed to have been exercised as to the First Extended Term by Tenant's
notification to Landlord that it elects to exercise its first option to extend
at least twelve (12) months but not more than eighteen (18) months prior to the
end of the initial Term hereunder, and as to the Second Extended Term by
Tenant's notification to Landlord that it elects to exercise its second option
to extend at least twelve (12) months but not more than eighteen (18) months
prior to the end of the First Extended Term. Each Extended Term shall be upon
the same terms and conditions as are set forth in this Lease, including, without
limitation, the Tenant's obligations to pay Operating Cost Escalation set forth
in Section 4.2, except that (i) there shall be no additional option to extend
after the termination of the Second Extended Term or the failure to exercise the
first option, whichever shall first occur, (ii) the annual Fixed Rent for the
First Extended Term shall be equal to the Market Rent (as defined in and
determined in accordance with Exhibit P), and (iii) the annual Fixed Rent for
the Second Extended Term shall be equal to the Market Rent (as defined and
determined in accordance with Exhibit P). In no event, however, shall the annual
Fixed Rent and additional rent for the First Extended Term and for the Second
Extended Term be less than the rent then in effect as of the last day
immediately preceding the First Extended Term or Second Extended Term, as
applicable.

<PAGE>   93

                                   EXHIBIT "G"

                              ESTOPPEL CERTIFICATE

     THIS CERTIFICATE is made to ___________________________ (the "Bank") with
respect to a lease dated _________________ execute by and between
________________________ (the "Landlord") and the undersigned (as "Tenant"),
covering a building (a portion of a building) located in _____________ (the
"Lease"), as amended by (list all amendments):

     The undersigned has been advised that the Bank is about to enter into a
transaction whereby the Bank is making a loan secured by the aforesaid real
estate and the Lease to the undersigned, and under which the Bank may acquire an
ownership interest in such real estate. In connection with this transaction, the
entire interest of the Landlord under the Lease to the undersigned will be
assigned to the Bank. The undersigned acknowledges that the Bank is and will be
relying upon the truth, accuracy and completeness of this letter in proceeding
with the transaction described above.

     The undersigned, for the benefit of the bank, their successors and assigns,
hereby certifies, represents, warrants, agrees and acknowledges that:

     1.   The Lease is in full force and effect in accordance with its terms
without modification or amendment except as noted above and the undersigned is
the holder of the Tenant's interest under the Lease.

     2.   The undersigned is in possession of all of the Premises described in
the Lease under and pursuant to the Lease and is doing business thereon; and the
premises are completed as required by the Lease.

     3.   The undersigned has no claims or offsets with respect to any of its
obligations as Tenant under the Lease, and neither the undersigned nor the
Landlord is claimed to be in default under the Lease.

     4.   The undersigned has not paid any rental or installments thereof in
advance of the due date as set forth in the Lease.

     5.   The undersigned has no notice of prior assignment, hypothecation or
pledge of rents of the Lease or the Landlord's interest thereunder or of the
Tenant's interest thereunder.

     6.   The term of the Lease has commenced and is presently scheduled to
expire on __________, ____. If there are any rights of extension or renewal
under the terms of the Lease, the same have not, as of the date of this letter,
been exercised.

     7.   Until such time as the Bank shall become the Landlord, if the
undersigned should assert a claim that the Landlord has failed to perform an
obligation to the undersigned under the terms of the Lease or otherwise, notice
thereof shall promptly be furnished to the Bank; and the undersigned agrees that
the undersigned will not exercise any rights which the undersigned might
otherwise have on account

<PAGE>   94

of any such failure until notice thereof has been given to the Bank, and the
Bank has had the same opportunity to cure any such failure as the Landlord may
have under the terms of the Lease.

     8.   Each of the statements set forth in Paragraphs 1 through 7 are true,
accurate and complete except as follows (state specifically any exception):

DATED

ATTEST:

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

                                           Its:
                                               ---------------------------------

                                       2
<PAGE>   95

                                   EXHIBIT "H"

                              INTENTIONALLY DELETED

<PAGE>   96

                                   EXHIBIT "I"

                                 PARK COVENANTS

     Landlord agrees with Tenant to enforce, or cause to be enforced, these Park
Covenants with all due diligence to preserve the quality and appearance of the
Park.

     The Lot is approximately ________________ (____) acres and is located in an
approximately ninety (90) acre office/research and development park shown on the
Plan of the Park attached hereto as part of Exhibit A and more particularly
described therein and elsewhere in this Lease, as the same, including without
limitation the Common Areas of the Park, may be amended by Landlord from time to
time in accordance with and subject to the provisions of Section 2.1 of this
Lease.

     All lots of land comprising the Park (which lots, including without
limitations the Lot, are individually called the "Parcel" and collectively the
"Parcels") are subject to the following restrictions which shall bind Michelson
Farm-Westford Technology Park Trust (collectively "Grantor") as original owner
of the Park and its successors in title.

     A.   All parcels shall have facilities for parking, loading and unloading
sufficient to serve any uses of the Parcels without using adjacent streets for
such purpose. On-street parking shall be prohibited. All parking, trucking and
vehicular maneuvering areas for a Parcel shall be contained within such Parcel.

     B.   No exterior loading platforms shall be visible from any primary way or
proposed primary way serving the Park. Screening and planting may be used for
this purpose.

     C.   No open or outside storage shall be done on any Parcel, other than
normal and customary trash compactors and containers on locations to be
reasonably approved by Landlord in advance.

     D.   Signs shall conform to the sign ordinances of the Town of Westford.
Any variance from such ordinance granted by the Town of Westford must also be
approved by Grantor in the manner provided below in Section I.

     E.   No condition or use of any Parcel will be permitted which is
objectionable by reason of noise, odor, vibration, smoke, radiation, the
hazardous nature of the use, or the violation of environmental laws or
regulations adopted by the Town of Westford, the Commonwealth of Massachusetts,
the Federal Government or any Court.

     F.   All utilities serving a Parcel shall be placed underground, unless
prohibited by the utility company. Any exterior lighting on a Parcel shall
either be indirect or of such controlled focus and intensity as not to disturb
street traffic or the occupancy of any adjacent Parcel.

     G.   The exterior appearance of any buildings in the Park, including
landscaping thereon, shall be kept neat and orderly and free from litter.

     H.   No building, exterior sign, fence, wall, exterior lighting or other
structure shall be erected or allowed to maintain on any portion of the Park or
exterior structural alteration or addition made,

<PAGE>   97

except pursuant to plans approved in writing by Grantor as to landscaping,
parking and architectural conformity with existing buildings in the Park.

     I.   The Grantor may from time to time by written instrument in recordable
form grant variance from any one or more of these restrictions (except
restriction H for which variances may not be granted) where the Grantor
reasonably determines that the variance can be granted without substantial
detriment to the intent and purpose of the restrictions and without substantial
detriment to the Land, and portions of the Park theretofore built upon.

     J.   Written approval by the Grantor as to any buildings, signs,
structures, alterations, additions and landscaping approved by Grantor in good
faith shall be conclusive evidence of compliance with these restrictions. The
Grantor agrees to furnish to any grantee such written instruments in recordable
form as may reasonably be requested by the grantee as evidence of such
compliance.

     K.   The term "Grantor", as herein used, shall mean Arthur J. Gutierrez and
John A. Cataldo, Class A Trustees, and Howard Stock and Marc D. Levy, Class B
Trustees, all as Trustees of Michelson Farm-Westford Technology Park Trust,
u/d/t dated October 1, 1984 and recorded with the Middlesex North District
Registry of Deeds in Book 2863, Page 235, and any of its successors in title to
whom the Grantor has expressly granted of record the rights to enforce these
restrictions.

                                       2
<PAGE>   98

                                   EXHIBIT "J"

                            LESSEE'S LEASE STATEMENT
                                       AND
             SUBORDINATION, NON-DISTURBANCE AND ATTORNMENT AGREEMENT

     THIS AGREEMENT is made and entered into as this ____ day of ___________,
2000, by and among ______________________________, a ___________________________
(hereinafter called the ("Lender"), ________________________ (hereinafter called
the "Tenant") and ______________________________ (hereinafter called the
"Landlord").

                                   WITNESSETH

     WHEREAS, Landlord owns certain real property commonly known as
_______________, ________________________ and located in _____________ County,
Massachusetts, and more particularly described in Exhibit "A" attached hereto
and made a part hereof (said property being hereinafter called the "Property");
and

     WHEREAS, Landlord and Tenant made and entered into that certain Lease,
dated as of the ___ day of ____________, 2000, with respect to certain premises
located on the Property constituting the Premises therein described, as the same
may be expanded pursuant to Exhibit "R" of the Lease (said Lease being
hereinafter called the "Lease" and said premises being hereinafter called the
"Leased Premises"), notice of which was recorded in the Middlesex _________
Registry of Deeds on _________________, 2000 as Instrument No. _______; and

     WHEREAS, Landlord has entered into and delivered that certain Mortgage and
Security Agreement in favor of Lender recorded in the Middlesex _________
Registry of Deeds on _______________, 2000 as Instrument No. ______ prior to the
recording of this Agreement (said Mortgage and Security Agreement being
hereinafter called the "Security Deed"), conveying the Property to secure the
payment of the indebtedness described in the Security Deed; and

     WHEREAS, on or about the date hereof, Landlord has entered into and
delivered that certain Assignment of Leases and Rents in favor of Lender
recorded in the Middlesex _______ Registry of Deeds on _______________, _______
as Instrument No. _________ prior to the recording of this Agreement (said
Assignment of Leases and Rents being hereinafter called the "Assignment of
Leases"), assigning all of Landlord's right, title and interest as lessor under
the Lease to further secure the indebtedness described in the Security Deed; and

     WHEREAS, the Lender represents that it is the sole holder of the Security
Deed and the Promissory Note and other loan documents secured thereby; and

     WHEREAS, the parties hereto desire to enter into this Non-Disturbance,
Attornment and Subordination Agreement;

<PAGE>   99

     NOW, THEREFORE, for and in consideration of the mutual covenants
hereinafter set forth and other good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, Lender, Tenant and Landlord hereby
covenant and agree as follows:

     1.   ESTOPPEL - Tenant hereby certifies to Lender that, as of the date of
this Agreement: (i) the Lease, as described above, is the true, correct and
complete Lease and has not been modified or amended and constitutes the entire
agreement between Landlord and Tenant, (ii) to the best of Tenant's knowledge,
without inquiry, there are no defaults of Landlord under the Lease and there are
no existing circumstances which with the passage of time, or giving of notice,
or both, would give rise to a default under the Lease and/or allow Tenant to
terminate the Lease, and (iii) Tenant is satisfied with all of the work done by
and required of Landlord to date, such work has been done in accordance with
plans and specifications approved by Tenant, and as of the date hereof Tenant is
not aware of any defect in the work or has not rejected any of the work done by
Landlord on the Leased Premises. If this Agreement is being delivered prior to
completion of all of Landlord's Work (as such term is defined in the Lease) on
the Leased Premises, Tenant agrees that, promptly after request of the Lender
therefor, it will provide an estoppel certificate to Lender following completion
of such work indicating whether Tenant has accepted the work and begun payment
of rent.

     2.   NON-DISTURBANCE - Lender agrees that if Lender comes into possession
of or acquires title to all or any part of the Leased Premises or the Lot (as
defined in the Lease) as a result of foreclosure or other enforcement of the
Security Deed or the Assignment of Leases, or both, then so long as no default
under the Lease by Tenant exists and continues beyond the expiration of all
applicable cure periods (after notice, if any, required by the Lease) as would
entitle the lessor under the Lease to terminate the Lease or would cause,
without any further action on the part of such lessor, the termination of the
Lease or would entitle the lessor under the Lease to exercise any other remedy
available to it on account of Tenant defaults under the Lease, the Lease shall
not be terminated, nor shall Tenant's use, possession or enjoyment of the Leased
Premises and appurtenant rights and interests or rights under the Lease be
interfered with. Following a foreclosure or other action or proceeding in the
nature of foreclosure instituted under or in connection with the Security Deed
or the Assignment of Leases, or the acquisition of title to the Leased Premises,
the person or entity acquiring the interest of the lessor under the Lease as a
result of any such action or proceeding or deed in lieu of any such action or
proceeding (hereinafter called the "Purchaser") or Lender if Lender takes
possession of the Property shall have all rights and obligations of Landlord
under the Lease, except as expressly otherwise set forth herein, provided,
however, that neither the Purchaser nor the Lender shall be (a) liable for any
act or omission of any prior lessor under the Lease provided that nothing herein
shall relieve such Purchaser or Lender from curing any continuing defaults of
lessor after receipt of requisite notices from Tenant, all in accordance with
the Lease; or (b) liable for the return of any security deposit which lessee
under the Lease has paid under the Lease unless such security deposit is
received by Lender; or (c) subject to any offsets or defenses which the lessee
under the Lease might have against any prior lessor under the Lease unless
Lender has received prior written notice of the offset or defense and
opportunity to cure the same in accordance with Section 7 below; or (d) bound by
any base rent, or any other payments which the lessee under the Lease might have
paid for more than the current month to any prior lessor under the Lease; or (e)
bound by any amendment or modification of the Lease made without Lender's prior
written consent (Lender hereby agreeing not to unreasonably withhold or delay
its consent); or (f) bound by any assignment or sublease of the lessee's
interest in the Lease made without obtaining Lender's prior written consent
(such consent not to be unreasonably withheld or delayed), except where the
consent of the Landlord is

                                       2
<PAGE>   100

not required pursuant to the provisions of Section 6.1.6 of the Lease (in which
event no consent of Lender shall be required); or (g) personally liable for any
default under the Lease or any covenant or obligation on its part to be
performed thereunder as lessor, it being acknowledged that Tenant's sole remedy
in the event of such default shall be to proceed against Purchaser's or Lender's
interest in the Property and the rents, or other proceeds arising therefrom.

     In the event that Lender acquires title to or possession of all or any part
of the Leased Premises, whether pursuant to a foreclosure proceeding or
otherwise, then within thirty (30) days thereafter, the Lender may elect to
deliver a written notice to the Tenant stating that either (i) the Lender
intends to perform the construction obligations of the Landlord set forth in
Article III of the Lease (the "Construction Obligations"), or (ii) the Lender
does not intend to perform the Construction Obligations. A notice delivered by
the Lender pursuant to clause (i) is referred to herein as an "Opt-In
Construction Notice" and a notice delivered by the Lender pursuant to clause
(ii) is referred to herein as an "Opt-Out Construction Notice".

     In the event that the Lender does not deliver either an Opt-Out
construction Notice or an Opt-In Construction Notice to the Tenant within said
thirty (30) days after acquisition of title or possession, then Tenant may elect
to deliver a written request (a "Construction Confirmation Request") to the
Lender, requesting that Lender deliver either an Opt-Out Construction Notice or
an Opt-In Construction Notice.

     If either (a) Lender delivers an Opt-Out Construction Notice to Tenant as
aforesaid, or (b) Lender does not deliver an Opt-In Construction Notice to
Tenant by not later than thirty (30) days after receipt of Tenant's Construction
Confirmation Request, then Lender shall not be obligated to perform the
Construction Obligations in accordance with the terms and provisions the Lease.
If Lender delivers an Opt-In Construction Notice as aforesaid, then Lender shall
be obligated to perform the Construction Obligations in accordance with the
terms and provisions of the Lease. If Lender timely delivers an Opt-Out
Construction Notice to Tenant by not later than thirty (30) days after receipt
of Tenant's Construction Confirmation Request as aforesaid, or Lender does not
deliver an Opt-In Construction Notice to Tenant by not later than thirty (30)
days of its receipt of Tenant's Construction Confirmation Request, then (a)
Lender shall have no obligation to perform the Construction Obligations, and (b)
Tenant may elect to terminate the Lease by providing written notice of such
election to Lender. If Tenant elects to terminate the Lease, the Lease shall be
terminated effective as of the date specified in Tenant's notice. Thereafter the
Lease shall be null and void and of no further force or effect, and neither the
Tenant nor the Lender shall have any further liabilities or obligations
thereunder.

     If (a) Lender sells, conveys, assigns, pledges or transfers its interest in
the Loan, or (b) Lender sells the Leased Premises, or any part thereof, at a
foreclosure sale, or (c) if Lender acquires title to the Leased Premises and
subsequently conveys the Leased Premises, then, in any such event, concurrently
with such transaction, Lender shall transfer, assign and convey all right, title
and interest of the Lender in and to the Security Deposit then held by it, if
applicable, to such purchaser, assignee, or transferee. Notwithstanding anything
to the contrary contained in this Section, if Lender so transfers, assigns or
conveys all right, title and interest of the Lender in and to the Security
Deposit, if applicable, as aforesaid, then Lender shall have no liability for
the return of the Security Deposit.

                                       3
<PAGE>   101

     3.   ATTORNMENT - Unless the Lease is terminated in accordance with
Paragraph 2 or in accordance with the terms of the Lease, if the interests of
the lessor under the Lease shall be transferred by reason of the exercise of the
power of sale contained in the Security Deed (if applicable), or by any
foreclosure or other proceeding for enforcement of the Security Deed, or by deed
in lieu of foreclosure or such other proceeding, or if Lender takes possession
of the Property pursuant to any provisions of the Security Deed, Tenant shall be
bound to the Purchaser or Lender, as the case may be, under all of the terms,
covenants and conditions of the Lease for the balance of the term thereof and
any extensions or renewals thereof which may be effected in accordance with any
option therefor in the Leases with the same force and effect as if the Purchaser
or Lender were the lessor under the Lease, and Tenant, as lessee under the
Lease, does hereby agree to attorn to the Purchaser and Lender if it takes
possession of the Property, as its lessor under the Lease. Such attornment shall
be effective and self-operative without the execution of any further instruments
upon succession by Purchaser to the interest of the lessor under the Lease or
the taking of possession of the Property by Lender. Nevertheless, Tenant shall,
from time to time, execute and deliver such instruments evidencing such
attornment as Purchaser or Lender may reasonably require. The respective rights
and obligations of Purchaser, Lender and of the lessee under the Lease upon such
attornment, to the extent of the then remaining balance of the term of the Lease
and any such extensions and renewals, shall be and are the same as now set forth
in the Lease, except as otherwise expressly provided in Paragraph 2 above.

     4.   SUBORDINATION - Subject to the provisions of this Agreement, Tenant
hereby subordinates all of its rights, title and interest as lessee under the
Lease to the right, title and interest of Lender under the Security Deed, and
Tenant further agrees that the Lease now is and shall at all times continue to
be subject and subordinate in each and every respect to the Security Deed and to
any and all increases, renewals, modifications, extensions, substitutions,
replacements and/or consolidations of the Security Deed and to all sums secured
thereby with the same force and effect as if the Security Deed had been
executed, delivered and recorded prior to the execution and delivery of the
Lease.

     5.   OTHER CONDITIONS - Notwithstanding anything to the contrary contained
in this Agreement or in the Lease, Lender, Tenant and Landlord agree: (a) that
to the extent required by the Lease, and provided that (i) Tenant has not
defaulted in the payment of rent or other charges under the Lease, (ii) Landlord
has not defaulted in the payment of debt service or other payments under the
loan documents and (iii) neither Landlord or Tenant has filed a voluntary
petition in bankruptcy under Title 11 of the United States Code or had an order
for relief issued against it and not dismissed within thirty (30) days of
issuance or has filed any petition or answer seeking or acquiescing in any
reorganization, arrangement, composition, readjustment, liquidation, dissolution
or similar relief for itself under any present or future federal, state or other
law or regulation relating to bankruptcy, insolvency or other relief of debtors
or consented or acquiesced in the appointment of any custodian, trustee,
receiver, conservator or liquidator for it or all or any substantial part of its
property or made an assignment for the benefit of creditors, then in the event
of an insured casualty to the Leased Premises, and if Landlord satisfies the
conditions provided for hereafter, Lender shall hold the balance of any casualty
proceeds after proof and adjustment and shall use such funds for the following
purposes: (x) to pay costs and obligations secured by the Security Deed (the
"Secured Obligations") as such become due during the course of reconstruction or
repair of the Leased Premises (y) to reimburse Landlord, in accordance with the
terms and conditions set forth below, for the costs of reconstruction or repair
of the Leased Premises, and (z) upon completion of such reconstruction or
repair, to apply any excess to the payment of the Secured Obligations. Such
funds shall be made available as provided above upon the Landlord's prior

                                       4
<PAGE>   102

satisfaction of such conditions as the Lender may reasonably establish with
respect thereto (each of which must be complied with in a manner reasonably
satisfactory to the Lender, with all documents, instruments, agreements, or
evidence to be in form and substance satisfactory to the Lender), including
without limitation, the following (hereinafter referred to as the "Funding
Requirements"):

          (i)  delivery of estoppel certificate(s) or other satisfactory
          evidence that the Lease remains in full force and effect and will
          remain in full force and effect after such repair and restoration,
          without any right of termination or cancellation during the projected
          course of said repair or restoration;

          (ii) delivery of plans and specifications, construction budget,
          construction contract, and construction schedule for such repair and
          restoration, satisfactory to Lender;

          (iii) delivery of evidence of compliance with all applicable state,
          federal, and local laws, ordinances and regulations relating to such
          repair and restoration, and the issuance of all required permits,
          licenses and approvals relative thereto;

          (iv) delivery of evidence of the availability of any funds necessary
          to complete such repairs and restoration in excess of such proceeds,
          which funds, at the request of the Lender, shall be deposited with the
          Lender to be disbursed with such proceeds;

          (v)  builder's all risk insurance;

          (vi) rent loss insurance sufficient to pay all operating costs and
          debt service confirmed by the insurer to be available for the period
          of repair and restoration;

          (vi) evidence that the insurer under such policies of fire or other
          casualty insurance does not assert any defense to payment under such
          policies against Lender, Landlord or any tenant of the Leased
          Premises;

          (vii) execution of any documentation deemed reasonably necessary by
          the Lender to provide for the disbursement of such funds in a manner
          typical to a construction loan;

          (viii) delivery of evidence that the repair or restoration can be
          completed prior to the then applicable maturity date of the note;

          (ix) Landlord delivers to Lender a written undertaking to
          expeditiously commence and to satisfactorily complete with due
          diligence the necessary restoration; and

          (x)  compliance of such other reasonable non-financial terms and
          conditions customary for construction loans of the size and scope
          involved with such repairs and restoration.

     6.   ASSIGNMENT OF LEASES - Tenant hereby acknowledges that all of
Landlord's right, title and interest as lessor under the Lease is being duly
assigned to Lender pursuant to the terms of the Assignment of Leases, and that
pursuant to the terms thereof all rental payments under the Lease shall

                                       5
<PAGE>   103

continue to be paid to Landlord in accordance with the terms of the Lease unless
and until Tenant is otherwise notified in writing by Lender. Upon receipt of any
such written notice from Lender, Tenant covenants and agrees to make payment of
all rental payments then due or to become due under the Lease directly to Lender
or to Lender's agent designated in such notice and to continue to do so until
otherwise notified in writing by Lender. Landlord hereby irrevocably directs and
authorizes Tenant to make rental payments directly to Lender following receipt
of such notice and covenants and agrees that Tenant shall have the right to rely
on such notice without any obligation to inquire as to whether any default
exists under the Security Deed or the Assignment of Leases or the indebtedness
secured thereby, and notwithstanding any notice of claim of Landlord to the
contrary, that Landlord shall have no right or claim against Tenant for or by
reason of any rental payments made by Tenant to Lender following receipt of such
notice. Except as otherwise specifically set forth in the Lease, Tenant further
acknowledges and agrees: (a) that under the provisions of the Assignment of
Leases, the Lease cannot be terminated (nor can Landlord accept any surrender of
the Lease) or modified in any of its terms, or consent be given to the waiver or
release of Tenant from the performance or observance of any obligation under the
Lease without the prior written consent of Lender, and without such consent, no
rent may be collected or accepted by Landlord more than one month in advance;
and (b) that the interest of Landlord as lessor under the Lease has been
assigned to Lender for the purposes specified in the Assignment of Leases, and
Lender assumes no duty, liability or obligation under the Lease, except only
under the circumstances, terms and conditions specifically set forth in the
Assignment of Leases or this Agreement.

     7.   NOTICE OF DEFAULT BY LESSOR - Tenant, as lessee under the Lease,
hereby covenants and agrees to give Lender written notice properly specifying
wherein the lessor under the Lease has failed to perform any of the covenants or
obligations of the lessor under the Lease simultaneously with the giving of any
notice of such default to the lessor under the provisions of the Lease. Tenant
agrees that Lender shall have the right, but not the obligation, within thirty
(30) days after receipt by Lender of such notice (or, with respect to
non-monetary defaults only, within such additional time as is reasonably
required to correct any such default) to correct or remedy, or cause to be
corrected or remedied, each such default before the lessee under the Lease may
take any action under the Lease by reason of such default; provided however, in
no event shall such time extend for more than sixty (60) days after Tenant
provides such notice to Lender, except if Lender has commenced to cure any such
non-monetary default under the Lease (which shall in no event include
foreclosure or exercise of other remedies available under the Security Deed)
within thirty (30) days after such written notice to Lender and is diligently
proceeding to cure such default and such non-monetary default cannot be cured
within sixty (60) days despite such diligent efforts to cure on the part of
Lender, in which event such time period may be extended for an additional period
of not more than thirty (30) days. Such notices to Lender shall be delivered in
duplicate in writing by registered or certified mail, return receipt requested,
or by depositing the same with an overnight commercial courier (such as Federal
Express) or by hand delivery to:

                            ________________________
                            ________________________
                            ________________________
                            Attention:______________

or to such other address as the Lender shall have designated to Tenant by giving
written notice to Tenant, prior to the Term Commencement Date at:

                                       6
<PAGE>   104

                            ________________________
                            ________________________
                            ________________________
                            Attention:______________

after the Term Commencement Date at:

                            ________________________
                            ________________________
                            ________________________
                            Attention:______________

or to such other address as may be designated by written notice from Tenant to
Lender.

     8.   NO FURTHER SUBORDINATION - Except as expressly provided to the
contrary in Paragraph 4 hereof, Landlord and Tenant covenant and agree with
Lender that there shall be no further subordination of the interest of lessee
under the Lease to any lender or to any other party without first obtaining the
prior written consent of Lender. Any attempt to effect a further subordination
of lessee's interest under the Lease without first obtaining the first written
consent of Lender shall be null and void.

     9.   CONSENT - Lender hereby consents to the Lease.

     10.  TRADE FIXTURES OR EQUIPMENT - The lien of the Security Deed does not
encumber any trade fixtures or equipment used by Tenant in its business on the
Property.

     11.  AS TO LANDLORD AND TENANT - As between Landlord and Tenant, Landlord
and Tenant covenant and agree that nothing herein contained nor anything done
pursuant to the provisions hereof shall be deemed or construed to modify the
Lease.

     12.  AS TO LANDLORD AND LENDER - As between Landlord and Lender, Landlord
and Lender covenant and agree that nothing herein contained nor anything done
pursuant to the provisions thereof shall be deemed or construed to modify the
Security Deed or the Assignment of Leases.

     13.  TITLE OF PARAGRAPHS - The titles of the paragraphs of this agreement
are for convenience and reference only, and the words contained therein shall in
no way be held to explain, modify, amplify or aid in the interpretation,
construction or meaning of the provisions of this agreement.

     14.  GOVERNING LAW - This agreement shall be governed by and construed in
accordance with the laws of the Commonwealth of Massachusetts.

     15.  PROVISIONS BINDING - The terms and provisions hereof shall be binding
upon and shall inure to the benefit of the heirs, executors, administrators,
successors and permitted assigns, respectively, of Lender, Tenant and Landlord.
The reference contained to successors and assigns of

                                       7
<PAGE>   105

Tenant is not intended to constitute and does not constitute a consent by
Landlord or Lender to an assignment by Tenant where such consent is required
under the Lease, but has reference only to those instances in which the lessor
under the Lease and Lender shall have given written consent to a particular
assignment by Tenant thereunder where such consent is required under the Lease.

     In the event of any transfer of the Security Deed or the note secured
thereby, the Lender shall transfer and deliver to the transferee any security
deposit under the Lease held by Lender or its agent, and provided the transferee
assumes the obligations of Lender hereunder or otherwise recognizes the
provisions hereof by written instrument, Lender shall thereupon become freed and
relieved of all covenants and obligations of the Lender hereunder, except with
respect to any breaches of this Agreement as shall have theretofore occurred.

     16.  COUNTERPARTS - This Agreement may be executed in two or more
counterparts, each of which shall be deemed an original, but all of which
together shall constitute one and the same instrument.

     17.  MODIFICATION - This Agreement may not be modified orally or in any
manner other than by an agreement in writing signed by the parties hereto or
their respective successors in interest.

     IN WITNESS WHEREOF, the parties have executed this Agreement as an
instrument under seal and hereunto set their respective hands and seals as of
the day, month and year first above written.

                                         LENDER:

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

                                         BY:
                                         ---------------------------------------

                                         TITLE:
                                         ---------------------------------------

                                         TENANT:

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

                                         BY:
                                         ---------------------------------------

                                         TITLE:
                                         ---------------------------------------

                                         LANDLORD:

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

                                         BY:
                                         ---------------------------------------

                                         BY:
                                         ---------------------------------------

                                       8
<PAGE>   106

                          COMMONWEALTH OF MASSACHUSETTS

______________ County, SS                                  _______________, 2000

     Then personally appeared before me _______________, the ___________________
of ________________________, to me personally known, who I am satisfied signed
the foregoing instrument, and who did acknowledge under oath that he/she signed
and delivered the same in his/her capacity as ________________ and that the
foregoing instrument is his/her free act and deed and the free act and deed of
such ____________________________.

                                             -----------------------------------
                                             Notary Public
                                             My Commission Expires:

                          COMMONWEALTH OF MASSACHUSETTS

____________ County, SS.                                  ________________, 2000

     Then personally appeared before me _______________, the ___________________
of _____________________, to me personally known, who I am satisfied signed the
foregoing instrument, and who did acknowledge under oath that he/she signed and
delivered the same in his/her capacity as ________________ and that the
foregoing instrument is his/her free act and deed and the free act and deed of
such corporation.

                                             -----------------------------------
                                             Notary Public
                                             My Commission Expires:

                          COMMONWEALTH OF MASSACHUSETTS

__________________, SS.                                      _____________, 2000

     Then personally appeared before me _________________, as _________________,
to me personally known, who I am satisfied signed the foregoing instrument, and
who did acknowledge under oath that he signed and delivered the same in his
capacity as ___________ aforesaid and that the foregoing instrument is his free
act and deed as ____________ aforesaid.

                                             -----------------------------------
                                             Notary Public
                                             My Commission Expires:

                                       9
<PAGE>   107

                          COMMONWEALTH OF MASSACHUSETTS

__________________, SS.                                      _____________, 2000

     Then personally appeared before me ________________, as __________________,
to me personally known, who I am satisfied signed the foregoing instrument, and
who did acknowledge under oath that he signed and delivered the same in his
capacity as ___________ aforesaid and that the foregoing instrument is his free
act and deed as ____________ aforesaid.

                                             -----------------------------------
                                             Notary Public
                                             My Commission Expires:

                                       10
<PAGE>   108

                                   EXHIBIT "K"

                          LANDLORD, TENANT, CONTRACTOR
                              CHANGE PROPOSAL FORM

Project:         ____________________________________
                 ____________________________________     R______      NR_______
Proposal No.     ___________________ Date ___________
From: (Landlord) ____________________________________     BB_____      TW_______

To: (Contractor) ______________________________________
CC: (Tenant) __________________________________________

--------------------------------------------------------------------------------
Step 1:   Contractor:    Provide an estimate for the described work.
          Architect:     Develop proper plans and specifications to clarify
                         described work.
          DESCRIPTION:   (List Drawings)

          Landlord:__________________________ Reason:__________________________

--------------------------------------------------------------------------------
Step 2:   Contractor:    Proceed with work as definitive plans become available.

          Landlord:__________________________ Date: __________________________

--------------------------------------------------------------------------------
Step 3:   Cost of Work
          a.  Cost of the work                         $________________
              (See attached breakdown)
          b.  Add construction fee                     $________________
          Total Cost of Work                           $________________

Submitted by:___________________________________________    ____________________
Dennis G. Bailey, Vice President and Construction Manager   Date
--------------------------------------------------------------------------------
Step 4:   The submitted Cost of Work has been reviewed and is (not) approved.
          _________________________________________    ______________________
                         Architect                             Date

          Design Fees                                  $________________
          TOTAL COST OF PROPOSAL                       $________________
--------------------------------------------------------------------------------
Step 5:   FINAL ACTION

          a.  The Tenant ________________________ Hereby agrees to reimburse the
                              Name of Firm
              Landlord the Total Cost of Proposal shown in Step 4 above.

              ___________________________________________   __________________
                    Authorized Tenant's Representative             Date

          b.  This bulletin is approved (rescinded) and the work above is (not)
              to be performed. Cost of this work shall be included in Change
              Order No.____________

          _______________________________________________   __________________
                           Landlord                                Date

<PAGE>   109

                                   EXHIBIT "L"

                         DEFINITION OF COST OF THE WORK

REIMBURSABLE COSTS:

The following 18 numbered items shall be used to determine and calculate the
Cost of the Work:

1.   The term Cost of the Work shall mean costs necessarily incurred and paid by
     the Contractor in the proper performance of the work. Such costs shall be
     at rates not higher than the standard paid in the greater Boston area and
     shall include the items set forth below.

2.   Wages paid for labor in the direct employ of Gutierrez Construction Co.,
     Inc. ("Contractor") in the performance of the work under applicable
     collective bargaining agreements, or under a salary or wage schedule agreed
     upon by the Landlord, and Contractor, and including such welfare or other
     benefits, if any, as may be payable with respect thereto.

3.   Salaries of Contractor's personnel when stationed at the field office, in
     whatever capacity employed, and a proportionate share of the project
     manager and construction managers' salaries, whether at the job site or in
     the main office. Personnel engaged at shops or on the road in expediting
     the production or transportation of materials or equipment shall be
     considered as stationed a the field office and their salaries paid for that
     portions of their time spent on the work.

4.   Cost of contributions, assessments or taxes incurred during the performance
     of the work for such items as unemployment compensation and social
     security, insofar as such cost is based on wages, salaries or other
     remuneration paid to employees of the Contractor and included in the Cost
     of the Work under subparagraphs 2 and 3.

5.   The portion of reasonable travel and subsistence expenses of the Contractor
     or of his officers or employees incurred while traveling in discharge of
     duties connected with the work, but not including travel and expenses to
     and from the job site or to attend meetings..

6.   Costs of all materials, supplies and equipment incorporated in the work,
     including costs of transportation thereof.

7.   Payments made by the Contractor to subcontractors for work performed
     pursuant to subcontracts.

8.   Cost, including transportation and maintenance, of all materials, supplies,
     equipment, temporary facilities and hand tools not owned by the workers,
     which are consumed in the performance of the work, and cost less salvage
     value on such items used by not consumed which remain the property of the
     Contractor.

<PAGE>   110

9.   Rental charges of all necessary machinery and equipment, exclusive of hand
     tools, used at the site in performance of the work, whether rented from the
     Contractor or others including installation, minor repairs and
     replacements, dismantling, removal, transportation and delivery costs
     thereof, at rental charges consistent with those prevailing in the greater
     Boston area.

10.  Cost of premiums for all bonds required by Tenant.

11.  Sales, use, or similar taxes related to the work and for which the
     Contractor is liable, which are imposed by any governmental authority.

12.  Permit fees, royalties, damage or infringement of patents and costs of
     defending suits therefor, and deposits lost for causes other than due to
     the Contractor's negligence.

13.  Losses and expenses, not compensated by insurance or otherwise, sustained
     by the Contractor in connection with the work, provided they have resulted
     from causes other than the fault or neglect of the Contractor,
     subcontractors, or those for whom the Contractor is responsible. Such
     losses shall include settlements made with the written consent and
     reasonable approval by Landlord and Tenant. If, however, such loss requires
     reconstruction and the Contractor is placed in charge thereof, he shall be
     paid for his services a fee of ten percent (10%) of the cost of such work.

14.  Minor expenses such as telegrams, long distance telephone calls, telephone
     service at the site, expressage, drawing reproduction, mail service,
     special deliveries, and similar petty cash items incurred in connection
     with the Tenant's Work.

15.  Cost of all removal of debris and clean up.

16.  Costs incurred due to an emergency affecting the safety of persons and
     property.

17.  Other costs incurred in the performance of the work if and to the extent
     approved in advance in writing by the Tenant.

18.  The cost of temporary power and heat.

                                       2
<PAGE>   111

                                   EXHIBIT "M"

                                   ALLOWANCES

-    $3.50 per rentable square foot for Tenant's costs for project management,
     space planning, architectural and engineering for the Tenant's Work.
     Landlord hereby acknowledges and agrees that such allowance shall be paid
     by Landlord within ten (10) days of Landlord's receipt of an invoice
     therefore. It is hereby acknowledged and agreed to by Landlord that Tenant
     shall have the right to apply such portion of any unused allowance to other
     costs due from Tenant pursuant to Article III hereof, Tenant hereby
     acknowledging and agreeing that in no event shall Landlord be required to
     actually reimburse Tenant out-of-pocket for any such unused amount.

<PAGE>   112

                                   EXHIBIT "N"

                      PROPOSED EXPANDED BUILDING FOOTPRINT
                                  AND SITE PLAN

     Phase II as shown on Plans entitled A1.1, A1.2 and A1.3, prepared by
Symmes, Maini & McKee Associates, Inc. (see plans attached to Exhibit "A"), and
Sheet C3 labeled "Westford Technology Park" dated February 16, 2000.

<PAGE>   113

                               [BUILDING LAYOUT]

<PAGE>   114

                                   EXHIBIT "O"

                             GUARANTY OF COMPLETION

     WHEREAS, Michelson Farm-Westford Technology Park, u/d/t dated October 1,
1984, and recorded with the Middlesex North Registry of Deeds in Book 2863, Page
235 ("Landlord") entered into a Lease dated as of March ___, 2000 (hereinafter,
the "Lease"), with Unisphere Solutions, Inc. ("Tenant") with respect to certain
demised premises located in the building situated at 11 Technology Park Drive,
Westford, Massachusetts (as in the Lease more particularly defined, the
"Premises"), and

     WHEREAS, The Gutierrez Company is the managing member of the Landlord; and

     WHEREAS, as an inducement to Tenant to enter into the Lease, the
undersigned will guaranty the construction obligations of Landlord under Article
III and Exhibit R of the Lease.

     NOW, THEREFORE, in consideration of the Lease and the covenants herein set
forth, and for other good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, the undersigned hereby agrees as
follows:

     The undersigned hereby absolutely and unconditionally guarantees to Tenant
the due and punctual performance of all of Landlord's or of Landlord's general
contractor's (Gutierrez Construction Co., Inc.'s) construction obligations and
responsibilities as Landlord under Article III of the Lease, including, without
limitation, the warranties set forth in Section 3.7 of the Lease, and of all the
expansion obligations and responsibilities of Landlord or its general
contractors as aforesaid under Exhibit R thereof, and including the payment and
discharge of all claims and demands for labor used for or in connection with the
construction and equipping of such construction so that the property upon which
the Premises is located shall be and remain free and clear of mechanics' and
materialmen's liens, but excluding all claims and demands for labor and
materials used for or in connection with the Tenant's work not constructed by
Landlord or its general contractor pursuant to Article III or Exhibit R of the
Lease.

     The undersigned hereby covenants and agrees that, upon written notice by
Tenant, but only after default by Landlord, or its general contractor, as the
case may be, and expiration of applicable grace periods set forth in the Lease,
or if none, thirty (30) days upon receipt of such notice from Tenant, it will
promptly perform all of such construction responsibilities of Landlord under
said Article III or Exhibit R of the Lease during the construction of the
Building of which the Premises form a part.

     The undersigned hereby agrees, as principal obligor and not as a guarantor
only, to pay to Tenant forthwith upon demand all costs and expenses (including
court costs and reasonable legal fees) incurred or expended by Tenant in
connection with this Guaranty and the defense and/or enforcement hereof.

     No provision of this Guaranty can be changed, waived or discharged except
by an instrument in writing signed by Tenant and the undersigned. No course of
dealing or delay or omission on the part of Landlord in exercising any right
shall operate as a waiver thereof or otherwise be prejudicial thereto.

     This Guaranty is intended to take effect as a sealed instrument to be
governed by and construed in accordance with the laws and courts of the
Commonwealth of Massachusetts and shall inure to the

<PAGE>   115

benefit of Tenant and its successors and assigns, and shall be binding on the
undersigned and its successors and assigns.

     IN WITNESS WHEREOF, the undersigned has executed this Guaranty under seal
on this _____ day of ________, 2000.

                                           GUARANTOR:
                                           THE GUTIERREZ COMPANY

                                           By:
                                           -------------------------------------
                                                  Arturo J. Gutierrez
                                                  President

                          COMMONWEALTH OF MASSACHUSETTS

COUNTY OF MIDDLESEX

     Then appeared the above named Arturo J. Gutierrez, the President of The
Gutierrez Company, who acknowledged the foregoing instrument to be his free act
and deed in his capacity as aforesaid, before me, this ___ day of ___________,
2000.

                                            ------------------------------------
                                                      NOTARY PUBLIC
                                                      My Commission Expires:

                                       2
<PAGE>   116

                                   EXHIBIT "P"

                                   MARKET RENT

     The market rent for the Premises shall be the then fair market rent for
similar space in similar Class A office buildings in the Town of Westford, which
such rent (the "Market Rent") shall be determined as follows:

(a)  The Market Rent shall be proposed by Landlord within fifteen (15) days of
     receipt of Tenant's notice that it intends to exercise its option to extend
     the Term as specified in Exhibit F of this Lease hereof (the "Landlord's
     Proposed Market Rent"). The Landlord's Proposed Market Rent shall be the
     Market Rent unless Tenant notifies Landlord, within fifteen (15) days of
     Tenant's receipt of Landlord's Proposed Market Rent, that Landlord's
     Proposed Market Rent is not satisfactory to Tenant ("Tenant's Rejection
     Notice").

(b)  If Tenant delivers Tenant's Rejection Notice and the Market Rent is not
     otherwise agreed upon by Landlord and Tenant within forty-five (45) days
     after Landlord's receipt of Tenant's notice that it intends to exercise its
     option to extend the Term, then the Market Rent shall be determined by the
     following appraisal procedure:

     1.   Within five (5) days of the expiration of said forty-five (45) day
          period, Tenant shall give notice to Landlord, which notice shall
          specify the name and address of the appraiser designated by Tenant
          (the "Tenant's Appraisal Notice"). Landlord shall within five (5) days
          after receipt of Tenant's Appraisal Notice, notify Tenant of the name
          and address of the appraiser designated by Landlord. Such two
          appraisers shall, within twenty (20) days after the designation of the
          second appraiser, make their determinations of the Market Rent in
          writing and give notice thereof to each other and to Landlord and
          Tenant. Such two (2) appraisers shall have twenty (20) days after the
          receipt of notice of each other's determination to confer with each
          other and to attempt to reach agreement as to the determination of the
          Market Rent. If such appraisers shall concur in such determination,
          they shall give notice thereof to Landlord and Tenant and such
          concurrence shall be final and binding upon Landlord and Tenant. If
          such appraisers shall fail to concur as to such determination within
          said twenty (20) day period, they shall give notice thereof to
          Landlord and Tenant and shall immediately designate a third appraiser.
          If the two appraisers shall fail to agree upon the designation of such
          third appraiser within five (5) days after said twenty (20) day
          period, then they or either of them shall give notice of such failure
          to agree to Landlord and Tenant and if Landlord and Tenant fail to
          agree upon the selection of such third appraiser within five (5) days
          after the appraiser(s) appointed by the parties give notice as
          aforesaid, then either party on behalf of both may apply to the
          American Arbitration Association or any successor thereto, or on his
          or her failure, refusal or inability to act, to a court of competent
          jurisdiction, for the designation of such third appraiser.

     2.   All appraisers shall be independent real estate appraisers or
          consultants who shall have had at least seven (7) years continuous
          experience in the business of appraising real estate in the suburban
          Boston area.

<PAGE>   117

     3.   The third appraiser shall conduct such hearings and investigations as
          he or she may deem appropriate and shall, within ten (10) days after
          the date of his or her designation, make an independent determination
          of the Market Rent.

     4.   If none of the determinations of the appraisers varies from the mean
          of the determinations of the other appraisers by more than ten (10%)
          percent, the mean of the determinations of the three (3) appraisers
          shall be the Market Rent for the Premises. If, on the other hand, the
          determination of any single appraiser varies from the mean of the
          determinations of the other two (2) appraisers by more than ten (10%)
          percent, the mean of the determination of the two (2) appraisers whose
          determinations are closest shall be the Market Rent.

     5.   The determination of the appraisers, as provided above, shall be
          conclusive upon the parties and shall have the same force and effect
          as a judgment made in a court of competent jurisdiction.

     6.   Each party shall pay fees, costs and expenses of the appraiser
          selected by it, its own counsel fees, and one-half (1/2) of all other
          expenses and fees of any such appraisal.

                                       2
<PAGE>   118

                                   EXHIBIT "Q"

                     EXISTING EXCLUSIVE USES AND EXCLUSIONS

EXCLUSIONS:

Lotus - Building 3 Lease
     -    Novell
     -    Netscape
     -    Microsoft
     -    Hewlett Packard

Emerson - Building 7 Lease
     -    Tenants whose principal use is offering medical and diagnostic
     treatment services and/or health education and wellness promotion
     educational services

Chili's
     -    Restaurant exclusion for 3-mile radium of Westford Technology Park
     excluding cafeterias in buildings

RIGHTS OF FIRST REFUSAL:

Lotus - Building 3 Lease
     -    Building 4
     -    Building 6

Lotus - Building 1 Lease
     -    Building 1

Emerson - Building 7 Lease
     -    Building 7

RIGHTS OF FIRST OFFER:

ENSR - Building 2 Lease
     -    Building 2 - any space that becomes available

<PAGE>   119

                                   EXHIBIT "R"

                                EXPANSION OPTION

     Landlord (including Landlord's affiliates, successors and assigns and all
other successors in title) agrees it shall hold available, subject to the
conditions of this Exhibit R, for Tenant Lot 10E, as described in Exhibit A-1
and in Exhibit N of this Lease (the "Expansion Land") required to support one
contiguous expansion of the Building by Landlord for Tenant for a total of up to
seventy-five thousand (75,000) rentable square feet of additional space (the
"Expansion Space"). Landlord acknowledges and agrees not to construct or permit
the construction of any buildings in, on or under the Expansion Land, and not to
use the Expansion Land for purposes other than for providing the required
parking, additional parking and access to Tenant pursuant to the provisions of
Section 10.14 of the Lease, subject to the conditions of this Exhibit R. The
size and footprint of the Expansion Space shall be determined by Landlord and
Tenant provided, however, that such expansion shall be a three (3) story
building consisting of seventy-five thousand (75,000) square feet, and shall
provide Tenant with an additional two hundred twenty-two (222) parking spaces,
and that the footprint and parking of such expansion shall be within the general
building footprint and parking areas shown on the Proposed Expanded Building
Footprint & Site Plan, prepared by Symmes, Maini & McKee Associates, dated
February 16, 2000, attached as Exhibit N to this Lease (the "Expanded Building
Site Plan"), or such other area as is reasonably agreed upon by Landlord and
Tenant. So long as there does not then exist any uncured, continuing Event of
Default and this Lease is then in existence and in full force and effect, so
long as Tenant is then leasing including (subleasing) at least one hundred
percent (100%) of the Building, and so long as such expansion option has not
been terminated in accordance with paragraph I. of this Exhibit R, Landlord
shall be required to hold the Expansion Land available as aforesaid, or to cause
an affiliate, successor or assign of Landlord or any other successor in title to
hold the Expansion Land available as aforesaid, necessary for said Expansion
Space, until the option for the Expansion Space has been terminated in
accordance with paragraph I. of this Exhibit R or until such date which is
twelve (12) months after the Term Commencement Date of this Lease, or until such
expansion has been constructed, whichever is sooner.

     Landlord shall exercise good faith efforts to obtain, simultaneously with
the approvals and permits necessary for construction of the original Building,
any and all approvals and permits, including but not limited to all zoning,
subdivision, wetlands and environmental permits and approvals, necessary for the
construction of the Expansion Space generally similar to the footprint and site
plan shown on the Expanded Building Site Plan. In the event that any of the
applicable authorities require modifications to the Expanded Building Site Plan,
then Landlord and Tenant hereby further agree that they will work and cooperate
with each other to reach a mutual agreement on any such modifications, provided,
however, that in no event shall such modifications result in the Expansion Space
containing less than seventy-five thousand (75,000) rentable square feet.

     If, after having exercised good faith efforts, Landlord is unable to obtain
all such necessary permits and approvals for the construction of the Expansion
Space by the Expansion Permit Date, as defined in paragraph I. below, as it may
be extended, then this Exhibit R, including paragraph I., shall be null and void
and of no further force and effect, and Landlord, or its affiliate, shall no
longer be required to hold the Expansion Land required for the Expansion Space
for Tenant as contemplated hereunder.

<PAGE>   120

I.   EXPANSION SPACE

     (i)  In the event that Tenant desires to exercise its option to lease and
occupy the Expansion Space, and there does not then exist any uncured,
continuing Event of Default hereunder, and Tenant is leasing and occupying at
least one hundred percent (100%) of the Building, written notice of Tenant's
intention to lease and occupy such Expansion Space (the "Expansion Notice") must
be given to Landlord not later than such date which is twelve (12) months after
the Term Commencement Date of this Lease (the "Expansion Exercise Date"). If
Tenant elects to expand by leasing and occupying the Expansion Space (the "Lease
for the Expansion Space") as herein provided, the annual Fixed Rent for the
Expansion Space shall be an amount equal to the following:

     Years 1-5:  $1,191,000.00/Year; $99,262.50/Month; $15.88/RSF
     Years 6-10:  $1,415,250.00/Year; $117,938.00/Month; $18.87/RSF
     (Note: These figures reflect an adjustment for cleaning of an estimated
15,000 square feet of lab area)

     Notwithstanding anything to the contrary contained in this Paragraph I. of
this Exhibit R, in the event that the Term of this Lease is extended beyond the
initial ten (10) year Term of this Lease as a result of Tenant exercising its
expansion option hereunder in conformity with the foregoing provisions, then
such Term shall be extended, subject to the provisions of this Exhibit R
(including the next full paragraph) for such additional period as necessary to
comply with the terms of this paragraph I. (the "Additional Extension Term"). In
such event, the Fixed Rent for the original Premises hereunder during the
Additional Extension Term shall be $18.86 per square foot.

     The Lease for the Expansion Space shall be in the same form as this Lease,
and, except as herein set forth, on the same terms and conditions as are set
forth in this Lease and shall be for a Term of ten (10) years. The Lease for the
Expansion Space shall provide for an Expansion Scheduled Term Commencement Date
(Landlord and Tenant hereby agreeing that such date occur no later than twelve
(12) months following the Expansion Notice by Tenant) and an Expansion Term
Commencement Date, the former to be mutually agreed upon by Landlord and Tenant
in good faith, but in no event less than thirty-six (36) weeks or more than
forty-four (44) weeks after obtaining all required permits and approvals for
construction of the Expansion Space, considering such factors as weather and
material availability (it being agreed by Landlord and Tenant that such
Expansion Notice by Tenant occurring between October 1 and March 1 shall add two
(2) additional months to the Expansion Scheduled Term Commencement Date for such
space beyond that which would otherwise be expected). The Lease for the
Expansion Space shall also provide (i) for an Expansion Outside Delivery Date of
sixty (60) days after the Expansion Scheduled Term Commencement Date, (ii)
Tenant the right to cancel the Lease for the Expansion Space in the event that
the Expansion Space is not delivered on or before the Expansion Outside Delivery
Date, as extended for delays due to Force Majeure (up to an aggregate of
forty-five (45) days) or Tenant's Delay as therein described, and (iii) that the
Tenant's Plans for the Expansion Space prepared by and being delivered by Tenant
to Landlord are attached as an Exhibit to the Lease for the Expansion Space. The
proposed form of Lease for the Expansion Space shall be delivered by Landlord to
Tenant promptly after such Expansion Notice to Tenant, and a mutually agreed
upon form shall be executed by Landlord and Tenant within forty-five (45) days
from the date of Tenant's receipt of a proposed form of Lease for the Expansion
Space from Landlord in the form as herein required,

<PAGE>   121

unless such date is extended by mutual agreement of both parties hereto. Tenant
and Landlord shall use reasonable efforts, each acting in good faith, to execute
the Lease for the Expansion Space within said forty-five (45) days from the date
of Tenant's receipt of a proposed form from Landlord. Notwithstanding the
foregoing, Landlord and Tenant agree that any such Lease for the Expansion Space
may, at the sole option of Landlord, be in the form of a lease amendment to this
Lease, whereupon any references herein to the Lease for the Expansion Space
shall also be deemed to refer to any such amendment to this Lease, as the case
may be. Landlord and Tenant hereby further agree that in the event that the
parties enter into a Lease for the Expansion Space, as aforesaid, they shall
enter into an amendment to this Lease evidencing an agreement to extend the
initial Term of this Lease such that the expiration of the initial Term of this
Lease for the original Premises hereunder and of the Lease for the Expansion
Space for such additional space shall be coterminous.

     If not already obtained in connection with the construction of the original
Building, Landlord agrees to exercise good faith efforts to obtain all necessary
permits and approvals to construct the Expansion Space within twelve (12) months
after receipt of the Expansion Notice (the "Expansion Permit Date"). If Tenant
fails to exercise its option as to the Expansion Space, or exercises its option
in a timely manner but thereafter fails to execute and deliver the Lease for the
Expansion Space on or prior to the time period as hereinabove set forth in
accordance with the provisions of this Exhibit R, or, if after proceeding
diligently and using good faith efforts to obtain all required permits and
approvals to construct such space by the Expansion Permit Date, Landlord is
unable to obtain all of such permits and approvals, then, subject to the terms
and provisions contained in this Exhibit R, Tenant's option as to the Expansion
Space and the rights and obligations of both Landlord and Tenant under this
paragraph I. shall terminate forthwith and be of no further force and effect.

II.  ADDITIONAL EXPANSION PROVISIONS

     The building quality, plans and specifications for the Expansion Space
shall be in accordance with the Expanded Building Site Plan and specifications
substantially comparable to the Building initially leased herein, except as
hereinafter provided, which such plans and specifications shall be set forth in
the Lease for the Expansion Space. Without limiting the foregoing, the building
quality, fit and finish of the Expansion Space shall be substantially comparable
to the Building initially leased herein based on Landlord's Plans and Tenant's
Plans and specifications for the initial Building. In addition, the Expansion
Space shall be landscaped to the mutual satisfaction of Landlord and Tenant,
each acting reasonably.

     Landlord's obligation to construct the Expansion Space is contingent upon
Landlord's ability, using a good faith diligent effort, (i) to finance the
project cost of such Expansion Space, or such portion thereof as the Landlord
elects to finance, at the annual Fixed Rent as determined in paragraph I. above,
and (ii) to obtain applicable permits and approvals required under building,
zoning and environmental laws, codes, rules and regulations and other laws then
affecting the use and development of such land in order to construct the
Expansion Space in accordance with all of the terms of this Lease.

     Further notwithstanding any language to the contrary contained in this
Exhibit R, in the event that Tenant's option as to the Expansion Space expires
or has otherwise been terminated pursuant to the above provisions of this
Exhibit R, then Landlord shall have, at any time thereafter during the Term of
this Lease, the right to construct the Expansion Space (or a portion thereof),
and to determine whether it

<PAGE>   122

shall be contiguous to the Building or not, adjacent to the Building or
elsewhere on the Lot, and lease such space to any third party upon such terms
and conditions as are negotiated by Landlord in its sole and absolute discretion
and Tenant shall have no further rights thereto. Landlord and Tenant hereby
further acknowledge and agree that in such event, the Expansion Space may be
enlarged or reduced by Landlord, in accordance with applicable laws, codes,
rules and regulations. Such Expansion Space, whether for the original
contemplated square footage or greater or less than the amount as aforesaid,
shall be subject to the terms and conditions set forth in the first complete
paragraph of paragraph II. above (i.e. conditions as to building quality, fit
and finish). In connection therewith, and in connection with any Expansion Space
constructed pursuant to this Exhibit R, whether for Tenant or not, Landlord
shall (i) if necessary, relocate such portion of the Building Parking Area, as
designated on Exhibit A, to an area as close to the Building as reasonably
possible, specifically as designated by Landlord so long as such area is within
the relocation parking area shown on Exhibit A hereto (i.e. on Lots 10D and
10E), Tenant hereby agreeing that such relocation parking area described by
Landlord on Exhibit A is acceptable to Tenant, (ii) have the right to
temporarily access such portion of the Premises comprising a 5' area in side of
the north wall on floors 1-3 of the Building, as such area is shown as
cross-hatched on Exhibit A hereto, Landlord hereby agreeing to minimize any
interruptions to Tenant in connection therewith, and, (iii) if such Expansion
Space is not constructed for Tenant, (a) construct a demising wall between the
two (2) phases shown on said Exhibit A such that the Premises hereunder
(including all building systems) shall be independent of the Expansion Space,
Tenant hereby acknowledging in such event loss of the window line along the
north wall and (b) reduce the initial Building Parking Area by seventy-two (72)
parking spaces, if necessary, in accordance with and subject to the provisions
of Section 10.14 of this Lease. Subject to the foregoing provisions, Landlord
and Tenant hereby further agree that they shall enter into an agreement
amending, modifying or supplementing this Lease, if necessary, in order to
reflect the occupancy of the Building by any such additional tenant(s) other
than Tenant if the Expansion Space is constructed as so permitted by Landlord
hereunder.

<PAGE>   123

                                                                       EXHIBIT S

                     Westford Technology Park - Building 10
                  Preliminary Construction Schedule - 3/13/00

<TABLE>
<CAPTION>
------------------------------------------------------------------------------------------------------------------------------------
                                                                                                       2000
------------------------------------------------------------------------------------------------------------------------------------
                                                                               Apr        May         Jun         Jul         Aug
                                         Start      End                    ---------------------------------------------------------
Task Name                                Date       Date     Duration      3 10 17 24 1 8 14 22 30 5 12 19 26 3 10 17 24 31 7 14 21
------------------------------------------------------------------------------------------------------------------------------------
<S>                                   <C>        <C>        <C>            <C>        <C>          <C>        <C>           <C>
1.)  Site Work                          4/3/00    10/6/00   132.0 days
     Erosion/Siltation Control          4/3/00    4/14/00    10.0 days     -----
     Clearing & Grubbing               4/17/00    4/28/00    10.0 days          ------
     Site Excavation - Cuts & Fills     5/1/00    6/30/00    44.0 days                ------------------------
     Bldg. Excavation & Backfill       5/22/00    6/23/00    24.0 days                       --------------
     Site utilities                     7/3/00    8/30/00    42.0 days                                        ----------------------
     Gravel Below Paving & Walks       8/14/00    9/22/00    29.0 days                                                        ------
     Biluminous Paving (Binder)        8/25/00    8/30/00     4.0 days                                                             -
     Biluminous Paving (Finish)        10/2/00    10/6/00     5.0 days
     Granite Curbing                   9/18/00    10/6/00    15.0 days
     Landscaping                       9/18/00    9/26/00     7.0 days
2.)  C.I.P. Concrete                   5/22/00    9/14/00    81.0 days
     Foundations                       5/22/00    6/23/00    24.0 days                       --------------
     Slab on Grade                     7/10/00    7/14/00     5.0 days                                          ---
     Fill on Metal Decks                9/1/00    9/14/00     9.0 days
3.)  Precast Concrete                  8/14/00     9/8/00    19.0 days                                                        ------
4.)  Struct. Steel Joists/Decks        7/17/00    8/11/00    20.0 days                                             ----------
5.)  Misc. Metals                      8/28/00    9/29/00    24.0 days
6.)  Caulking                          10/4/00   10/27/00    17.0 days
7.)  Roofing                           10/4/00   10/31/00    19.0 days
8.)  Doors, Frames & Hardware         12/26/00     1/5/01     8.0 days
9.)  Aluminum Windows                   9/5/00   10/20/00    33.0 days
10.) Curtain Wall                      10/2/00   10/20/00    14.0 days
11.) Entry Doors                      10/20/00   10/26/00     5.0 days
12.) Overhead Doors                    9/18/00    9/22/00     5.0 days
13.) Gypsum Wallboard and Dryvit       10/2/00   12/15/00    52.0 days
14.) Ceramic Tile & Granite           11/20/00    12/1/00     9.0 days
15.) Accoustical Ceilings             11/14/00    12/8/00    18.0 days
16.) Carpeting/Resid. Flooring        12/26/00     1/5/01     8.0 days
17.) Painting                          11/7/00    1/31/01    57.0 days
18.) Toilet Access./Partitions        12/11/00   12/15/00     5.0 days
19.) Loading Dock Equipment            9/25/00    9/29/00     5.0 days
20.) Elevator Jack Hole                6/12/00    6/16/00     5.0 days                               ---
21.) Elevators                        10/10/00   12/15/00    47.0 days
22.) Plumbing (Underground)            6/19/00    6/30/00    10.0 days                                  ------
23.) Plumbing                          9/13/00   11/24/00    50.0 days
24.) Fire Protection                   9/13/00   11/27/00    51.0 days
25.) H.V.A.C.                          9/13/00    12/7/00    59.0 days
26.) Electrical (Underground)          6/19/00    6/30/00    10.0 days                              ----------
27.) Electrical                        9/15/00    9/15/00     0.0
28.) Start Tenant Improvements         1/31/01    1/31/01     0.0
</TABLE>

<TABLE>
<CAPTION>
---------------------------------------------------------------------------------------------------
                                                     2000                                 2001
---------------------------------------------------------------------------------------------------
                                         Sep          Oct          Nov       Dec       Jan     Feb
---------------------------------------------------------------------------------------------------
Task Name                          28 5 11 18 25 2 10 16 23 30 6 14 20 27 4 11 18 26 2 8 16 29 5 12
---------------------------------------------------------------------------------------------------
<S>                                <C>            <C>          <C>        <C>        <C>       <C>
1.)  Site Work
     Erosion/Siltation Control
     Clearing & Grubbing
     Site Excavation - Cuts & Fills
     Bldg. Excavation & Backfill
     Site utilities
     Gravel Below Paving & Walks   --------
     Biluminous Paving (Binder)
     Biluminous Paving (Finish)                  --
     Granite Curbing                       --------
     Landscaping                           -----
2.)  C.I.P. Concrete
     Foundations
     Slab on Grade
     Fill on Metal Decks              -----
3.)  Precast Concrete              -----
4.)  Struct. Steel Joists/Decks
5.)  Misc. Metals                  -------------
6.)  Caulking                                     ---------
7.)  Roofing                                      ----------
8.)  Doors, Frames & Hardware                                                     ----
9.)  Aluminum Windows                 -------------------
10.) Curtain Wall                                --------
11.) Entry Doors                                         --
12.) Overhead Doors                        ---
13.) Gypsum Wallboard and Dryvit                 ------------------------------
14.) Ceramic Tile & Granite                                         ------
15.) Accoustical Ceilings                                         ----------
16.) Carpeting/Resid. Flooring                                                    -----
17.) Painting                                                   ------------------------------
18.) Toilet Access./Partitions                                              ---
19.) Loading Dock Equipment                   --
20.) Elevator Jack Hole
21.) Elevators                                     ----------------------------
22.) Plumbing (Underground)
23.) Plumbing                             ----------------------------
24.) Fire Protection                      -----------------------------
25.) H.V.A.C.                             ---------------------------------
26.) Electrical (Underground)
27.) Electrical
28.) Start Tenant Improvements
</TABLE>
<PAGE>   124

                                   EXHIBIT "T"

                                 NOTICE OF LEASE

     In accordance with the provisions of Massachusetts General Laws (Ter. Ed.)
Chapter 183, Section 4, as amended, notice is hereby given of a certain lease
(hereinafter referred to as the "Lease") dated as of March ___, 2000 by and
between Arthur J. Gutierrez and John A. Cataldo, Class A Trustees and Howard
Stock And Marc D. Levy, Class B Trustees, all as Trustees of Michelson
Farm-Westford Technology Park Trust, under Declaration of Trust dated October 1,
1984, recorded with the Middlesex North District Registry of Deeds in Book 2863,
Page 235 (hereinafter referred to as "Landlord") and Unisphere Solutions, Inc.
(hereinafter referred to as "Tenant").

                                   WITNESSETH:

     1.   The address of the Landlord is c/o The Gutierrez Company, One Wall
          Street, Westford, Massachusetts 01803.

     2.   The address of the Tenant is 5 Carlisle Road, Westford, Massachusetts
          01886.

     3.   The Lease was executed on March ___, 2000.

     4.   The Term of the Lease is a period of ten (10) years beginning on the
          Term Commencement Date determined in accordance with Section 3.2 of
          the Lease, currently scheduled for January 31, 2001.

     5.   Subject to the provisions of the Lease, the Tenant has the option to
          extend the Term of the Lease for two (2) successive five (5) year
          terms pursuant to Exhibit "F" of the Lease.

     6.   The Tenant has an Expansion Option to lease up to seventy-five
          thousand (75,000) rentable square feet of additional space in the
          Building pursuant to Exhibit "R" of the Lease. The Expansion Land, as
          described in Exhibit "R" of the Lease, is known as Lot 10E and is
          described on Exhibit "A-1" attached hereto and made a part hereof.

     7.   The Lot and the Park, as such terms are defined in the Lease, are
          subject to the covenants and agreements contained in Exhibit "I" of
          the Lease.

<PAGE>   125

     8.   The demised premises is a three (3) story building containing
          approximately one hundred and fifty thousand (150,000) rentable square
          feet located at 11 Technology Park Drive, Westford, Massachusetts
          01886, and the areas of which are the subject of all appurtenant
          rights and easements set forth in Sections 2.1 and 10.14 of the Lease.

     9.   The deed(s) for the demised premises were recorded on ______________
          with the Middlesex North Registry of Deeds in Book     , Page    , as
          more particularly described on Exhibit "A" hereto.

     10.  The deed(s) for the Expansion Land were recorded on ______ with the
          Middlesex North Registry of Deeds in Book ______, Page ______, as more
          particularly described on Exhibit "A-1" hereto.

     11.  The Tenant has a Right of First Offer for the Buildings known as
          Buildings 2, 4 and 6 located within the Park pursuant to Exhibit "U"
          of the Lease.

     This Notice of Lease has been executed merely to give notice of the Lease,
and all of the terms, conditions and covenants of which are incorporated herein
by reference. The parties hereto do not intend this Notice of Lease to modify or
amend the terms, conditions and covenants of the Lease which are incorporated
herein by reference.

     IN WITNESS WHEREOF, the parties hereto have duly executed this Notice of
Lease this ___ day of ______________, 2000.

                                             LANDLORD:
                                             MICHELSON FARM-WESTFORD
                                             TECHNOLOGY PARK TRUST

                                             By:
                                                --------------------------------
                                                __________________, Class A
                                                Trustee of Michelson
                                                Farm-Westford Technology Park
                                                Trust, on behalf of himself and
                                                his co-Class A Trustee in their
                                                capacities as said trustees and
                                                not individually

                                             Dated:
                                                   -----------------------------

                                       2
<PAGE>   126

                                             By:
                                                --------------------------------
                                                __________________, Class B
                                                Trustee of Michelson
                                                Farm-Westford Technology Park
                                                Trust, on behalf of himself and
                                                his co-Class B Trustee in their
                                                capacities as said trustees and
                                                not individually

                                             Dated:
                                                   -----------------------------

                                             TENANT:
                                             UNISPHERE SOLUTIONS, INC.

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

                                             Its:
                                                 -------------------------------

                                             Dated:
                                                   -----------------------------

                          COMMONWEALTH OF MASSACHUSETTS

MIDDLESEX, SS.
     ____________, 2000
     Then personally appeared before me           , as trustee of Michelson
Farm-Westford Technology Park Trust and acknowledged the foregoing instrument to
be his free act and deed as trustee aforesaid.

                                             ___________________________________
                                             NOTARY PUBLIC
                                             My Commission Expires:

                                       3
<PAGE>   127

                          COMMONWEALTH OF MASSACHUSETTS

______________, SS.                                           ____________, 2000

     Then personally appeared before me           , as trustee of Michelson
Farm-Westford Technology Park Trust and acknowledged the foregoing instrument to
be his free act and deed as trustee aforesaid.

                                             ___________________________________
                                             NOTARY PUBLIC
                                             My Commission Expires:

                          COMMONWEALTH OF MASSACHUSETTS

_______________, SS.                                          ____________, 2000

     Then personally appeared before me ________________, as ________________ of
Unisphere Solutions, Inc., and acknowledged the foregoing instrument to be
his/her free act and deed as _________ aforesaid.

                                             ___________________________________
                                             NOTARY PUBLIC
                                             My Commission Expires:

                                       4
<PAGE>   128

                                   EXHIBIT "U"
                              RIGHT OF FIRST OFFER

     Subject to the last sentence of this paragraph, in no event shall Landlord
decide to lease, agree to lease, or accept any offer to lease space that becomes
available during the initial Term hereof the so-called Buildings 2, 4 and 6
within the Park and, unless Landlord first affords Tenant an opportunity to
lease such entire Building(s) in accordance with the provisions of this Exhibit
U and only after written notice to Tenant. Such notice shall contain the
proposed essential terms with respect to such rentable area (Landlord's summary
thereof, shall herein be referred to as the "Offer" or "Landlord's Offer"). The
Offer shall set forth all of the essential terms and conditions upon which
Landlord proposes to lease such space (i.e. the annual fixed rent amounts, the
operating expense base amounts, and the allowances). Upon receipt of such notice
and the Offer from Landlord, and provided further that there does not then exist
an uncured, continuing default under this Lease and provided further that the
Tenant is then leasing (including subleasing) one hundred percent (100%) of the
Premises, then Tenant shall have a right to lease any such space on the terms
set forth in the Offer by giving notice to Landlord to such effect within five
business (5) days after Tenant's receipt of Landlord's notice of such Offer. If
such notice is not so timely given by Tenant, then Landlord shall be free to
lease the subject space, or portion thereof, to any third party on the terms and
conditions contained in the Offer (or on such other terms and conditions as are
negotiated by Landlord in its sole discretion) at any time after the expiration
of said five (5) day period. The non-exercise by Tenant of its rights under this
Exhibit U as to any one Offer by Landlord shall not be deemed to waive any of
Tenant's rights of first offer as to other Building(s) aforesaid.
Notwithstanding any language to the contrary in this Exhibit U, Tenant's rights
of first offer hereunder (i) shall be subject and subordinate to the
pre-existing rights of other tenants, as such rights are set forth in Exhibit Q
of this Lease (ii) shall not revive and continue should such Building become
available after Tenant's waiver and subsequent leasing by Landlord, and (iii)
shall apply to the leasing of the entire Building(s) specified in the Offer and
not portions thereof.

     In the event that Tenant accepts Landlord's offer to lease such rentable
space in said Building(s), which is the subject of Landlord's Offer to Tenant,
then Landlord and Tenant hereby agree that they shall enter into a mutually
acceptable agreement amending, modifying or supplementing this Lease, specifying
that such rentable area is a part of the Premises under this Lease and demising
said premises to Tenant, or at Landlord's election, shall enter into a separate
lease agreement substantially in the form of this Lease, as modified to comply
with the terms of the Offer, with respect to such rentable space. Such amendment
(or separate lease agreement, as the case may be) shall also contain other
appropriate terms and provisions relating to the addition of such rentable space
to this Lease or the leasing of such rentable space, as applicable, and shall be
signed by Tenant within thirty (30) days of receipt of the proposed agreement
from the Landlord in the form as hereinabove required.

     Notwithstanding anything to the contrary in this Exhibit U, if Tenant
notifies Landlord of its election to lease such rentable space in said
Building(s) which was the subject of the Offer and then fails to execute and
deliver the required amendment to this Lease (or separate lease agreement, as
applicable) once the same has been mutually agreed upon by Landlord and Tenant
in accordance with this Exhibit U, then (i) Tenant shall be deemed to have
waived its rights to lease the offered space under this Exhibit U, (ii) Landlord
shall have the unrestricted right to lease such space upon whatever terms and
conditions as are negotiated by Landlord in its sole discretion; and (iii)
Tenant's right of first offer as to rentable space in the Building hereunder
shall terminate and be of no further force and effect. The recording by

                                       5
<PAGE>   129

the Landlord of an affidavit to such effect shall be conclusive evidence of the
termination or waiver of Tenant's first offer option hereunder. Otherwise, if
the Landlord and Tenant, each acting reasonably and in good faith, fail to agree
on a mutually agreeable form of amendment to this Lease (or separate lease
agreement, as the case may be) within said thirty (30) day period upon receipt
of Landlord's proposed form of agreement, unless such date is extended by mutual
agreement of both parties hereto, then such failure shall be treated as a
non-exercise by Tenant of its right of first offer in accordance with the first
Section of this Exhibit U and Landlord shall be free to lease the subject space,
or portion thereof, to a third party as aforesaid.

                                       6
<PAGE>   130
                                                                   EXHIBIT 10.20

                            FIRST AMENDMENT TO LEASE
                            ------------------------

     THIS FIRST AMENDMENT TO LEASE dated as of June 30, 2000 between MICHELSON
FARM - WESTFORD TECHNOLOGY PARK X LIMITED PARTNERSHIP, having a mailing address
c/o The Gutierrez Company, Burlington Office Park, One Wall Street, Burlington,
Massachusetts 01803, as landlord (the "Landlord"), and UNISPHERE SOLUTIONS,
INC., having a mailing address at 5 Carlisle Road, Westford, Massachusetts
01886, as tenant (the "Tenant").

                                   WITNESSETH

     WHEREAS, Landlord's predecessor and Tenant have entered into that certain
lease (the "Lease") dated as of March 31, 2000 with respect to 150,000 square
feet of space within a building (the "Building") located at Ten Technology Park
Drive, Michelson Farm-Westford Technology Park, Westford, Massachusetts;

     WHEREAS, since the execution of the Lease, the plan describing the lot upon
which the Building is located (as in the Lease more particularly defined as the
"Lot") has been recorded;

     WHEREAS, Tenant has elected to exercise its expansion option set forth in
Exhibit "R" of the Lease;

     WHEREAS, Landlord and Tenant have agreed to amend this Lease to set forth
the foregoing modifications.

     NOW, THEREFORE, Landlord and tenant, in consideration of the covenants and
agreements expressed herein and in the Lease, and other good and valuable
consideration, the receipt and the sufficiency of which are hereby acknowledged,
hereby agree that the Lease shall, on the Effective Date (as hereinafter defined
in Paragraph 10 below), be amended as follows:

     1.  The Lease is hereby amended by deleting the following as the Landlord,
     "Arthur J. Gutierrez and John A. Cataldo, Class A Trustees and Howard Stock
     and Marc D. Levy, Class B Trustees, all as Trustees of Michelson
     Farm-Westford Technology Park Trust, under Declaration of Trust dated
     October 1, 1984, recorded with the Middlesex North District Registry of
     Deeds in Book 2863, Page 235", and by replacing the same with "Michelson
     Farm-Westford Technology Park X Limited Partnership", such that all
     references in the Lease to Landlord shall now refer to said "Michelson
     Farm-Westford Technology Park X Limited Partnership.

     2.  Article I, Section 1.1 of the Lease is hereby amended as follows:

     a)  By deleting the address set forth in the seventh (7th) line of the
definition of "TENANTS' ADDRESS (FOR NOTICE AND BILLING)" of "11 Technology Park
Drive" and by replacing the same with "10 Technology Park Drive."
<PAGE>   131
     b)  By deleting the definition of "TERM EXPIRATION DATE" in its entirety
     and by replacing the same with the following: "Ten (10) years following the
     Term Commencement Date for the Phase II Lease (as hereinafter defined),
     subject to extension in accordance with Exhibit F. For purposes of this
     Lease, the "Phase II Lease" shall refer to that certain Lease dated ______,
     2000 and executed by and between Landlord and Tenant in connection with
     Phase II of the Building consisting of approximately 75,000 square feet."

     c)  By deleting the definition of "FIXED RENT" in its entirety and by
     replacing the same with the following:

     "FIXED RENT    Years 1-5:  $2,386,080.00/Year;
                                $198,840.00/Month;
                                ($15.91/RSF)

                    Years 6-10: $2,828,580.00/Year;
                                $235,715.00/Month;
                                ($18.86/RSF)

     Additional Extension Term (i.e. Years 11-Term Expiration Date, excluding
     any extension in accordance with Exhibit F):

                                $2,828,580.00/Year;
                                $235,715.00/Month;
                                ($18.86/RSF)

                    [To Be Adjusted by Section 3.1.1, if Applicable]".

     d)  By deleting "Expansion Option: Per Exhibit R" in the definition of
     "SPECIAL PROVISIONS" in its entirety.

3.   Article I, Section 1.2 of the Lease is hereby amended by (i) replacing the
Plan showing the Lot and Building Parking Area attached to the Lease as part of
Exhibit A and by replacing the same with the plan(s) attached hereto as Exhibit
A, and (ii) deleting "Exhibit R Expansion Option" in its entirety, with the
exception of Tenant's agreement allowing Landlord in connection with Tenant's
exercise of its expansion option and Landlord's construction thereof, "the right
to temporarily access such portion of the Premises comprising a 5 foot area
inside of the north wall on floors 1-3 of the Building, as such area is shown as
cross-hatched on Exhibit A" to the Lease, which such agreement is hereby
ratified and confirmed by Tenant. In addition, all references in the lease to
the "Exhibit R", the "Expansion Space" and the like shall be, and hereby are,
deleted.

4.   Section 9.1 of the Lease is hereby amended by adding the following after
"(vi) such leasehold is taken on execution or other process of law in any action
against Tenant"

                                       2
<PAGE>   132
in the eleventh line thereof: "or (vii) if there is a continuing, uncured Event
of Default by Tenant under the Phase II Lease (as defined in Section 1.1 of this
Lease)."

5.   Section 10.14 of the Lease is hereby amended by deleting the first
paragraph thereof in its entirety and by replacing the same with the following:

     "Tenant's occupancy of the Premises shall include the use of four (4)
parking spaces per 1,000 square foot of rentable floor area of the Premises.
Tenant's parking spaces shall be known and referred to in this Lease as the
"Building Parking Area", and shall be shown as such on the plans attached hereto
as Exhibit A. The Building Parking Area shall be used by Tenant in common with
other tenants of the Building, if applicable, including, without limitation,
tenant(s) of the Building described in the Phase II Lease (as defined in Section
1.1 hereof)."

6.   Exhibit "A-1" of the Lease is hereby amended by deleting the same in its
entirety and by replacing same with the following:

                                 EXHIBIT "A-1"

Two (2) parcels of land located on Technology Park Drive in Westford, Middlesex
County, Massachusetts shown as Lot 10D and Lot 10E on that certain plan entitled
"Revised Subdivision Plan of Land, Westford Technology Park, Westford, Mass"
prepared by Harry R. Feldman, Inc., dated May 1, 2000 and recorded with the
Middlesex North Registry of Deeds in Plan Book 203, Plan 47 (the "Plan"). Lot
10D contains 11.397 acres according to the Plan and Lot 10E contains 3.811 acres
according to the Plan (a copy of which Plan is attached hereto and made a part
hereof)."

7.   In the event that the Phase II Lease is terminated due to a casualty or
taking as provided in Article VII of the Phase II Lease, then Tenant shall also
have the right to terminate the Lease (i.e. Phase I Lease) at the time of
termination of the Phase II Lease.

8.   Except as modified hereinabove set forth, the Lease (as amended by this
First Amendment) is hereby ratified and confirmed.

9.   This First Amendment to Lease may be signed in any number of counterparts
and each thereof shall be deemed to be an original and all such counterparts but
one and the same agreement. Landlord's obligations to perform hereunder is
subject to the condition precedent that this First Amendment to Lease be
approved by Fleet National Bank.

10.  For purposes of this First Amendment, the Effective Date shall refer to the
Term Commencement Date under the Phase II Lease. In the event that the Term
Commencement Date under the Phase II Lease does not occur, then the provisions
of Paragraph 2(b), (c) and (d), Paragraph 3, Paragraph 4, Paragraph 5 and
Paragraph 6 of this First Amendment to Lease shall not be applicable.

                                      -3-
<PAGE>   133
     IN WITNESS WHEREOF, the parties have set their hands and seals the day and
year first above written.

                                        LANDLORD:
                                        MICHELSON FARM-WESTFORD
                                        TECHNOLOGY PARK X LIMITED
                                        PARTNERSHIP

                                        By: THE GUTIERREZ COMPANY,
                                            SOLE GENERAL PARTNER

/s/ [illegible]                         BY: /s/ Arturo J. Gutierrez
------------------------------------       -----------------------------------
                                            Arturo J. Gutierrez, as President

                                        TENANT:
                                        UNISPHERE SOLUTIONS, INC.

/s/ [illegible]                         BY:  /s/ James A. Dolce, Jr.
------------------------------------        -----------------------------------
Witness                                 ITS: President
                                            -----------------------------------

                                      -4-
<PAGE>   134
                              CONSENT OF MORTGAGEE

     The undersigned Mortgagee hereby consents and approves the terms and
provisions set forth in this First Amendment to Lease dated as of _______ __,
2000 by and between Michelson Farm - Westford Technology Park X Limited
Partnership ("Landlord") and Unisphere Solutions, Inc. ("Tenant").

                                        MORTAGAGEE:
                                        FLEET NATIONAL BANK

/s/ Kathleen L. Whalen                  BY:  /s/ Peter V. Chow
------------------------------------        -----------------------------------
Witness                                      Peter V. Chow
                                        ITS: Senior Vice President

                                        DATE: July 10, 2000

                                      -5-

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