Document:

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                                                                   Exhibit 10.18

                        AMENDMENT DATED DECEMBER 15, 2000
                                       TO
                1998 INCENTIVE PLAN OF LENNOX INTERNATIONAL INC.

The Plan is hereby amended to delete Paragraph 5 of the Plan, in its entirety,
and replace it with the following:

     "5. Common Stock Available for Awards. Subject to the provisions of
paragraph 15 hereof, there shall be available for Awards under this Plan granted
wholly or partly in Common Stock (including rights or options that may be
exercised for or settled in Common Stock) an aggregate of 7,541,635 shares of
Common Stock, of which an aggregate of not more than 660,000 shares shall be
available for Director Awards and the remainder shall be available for Employee
Awards and Independent Contractor Awards. The number of shares of Common Stock
that are the subject of Awards under this Plan, that are forfeited or
terminated, expire unexercised, are settled in cash in lieu of Common Stock or
in a manner such that all or some of the shares covered by an Award are not
issued to a Participant or are exchanged for Awards that do not involve Common
Stock, shall again immediately become available for Awards hereunder. The
Committee may from time to time adopt and observe such procedures concerning the
counting of shares against the Plan maximum, as it may deem appropriate. The
Board and the appropriate officers of the Company shall from time to time take
whatever actions are necessary to file any required documents with governmental
authorities, stock exchanges and transaction reporting systems to ensure that
shares of Common Stock are available for issuance pursuant to Awards."<PAGE>

                                                                   EXHIBIT 10.25

                                  AMENDMENT ONE
                                     to the
                          INTERCOMPANY CREDIT AGREEMENT
                                     between
                       ELECTRONIC DATA SYSTEMS CORPORATION
                                       and
                           UNIGRAPHICS SOLUTIONS INC.

     This Amendment One to the Intercompany Credit Agreement (the "Agreement")
by and between Electronic Data Systems Corporation, a Delaware corporation
("EDS") and Unigraphics Solutions Inc., a Delaware corporation ("USI"), is
effective as of September 1, 2000.

1.   Section 2.02 (ii) is hereby amended as follows:

          Effective upon the acceptance for payment by USI of shares of common
          stock of Engineering Animation Inc. under the tender offer by USI for
          such shares, the $70,000,000 limit on outstanding balances of all
          Advances from EDS to USI and all of its subsidiaries (including its
          non-U.S. subsidiaries that are parties to credit arrangements with EDS
          Finance plc) is hereby increased to $250,000,000 in the aggregate,
          provided, however, that the amount of such limit shall be reduced, up
          to a maximum reduction of $180,000,000, on a dollar-for-dollar basis
          by the amount of any term loan facility (including any term loan
          facility with EDS or its affiliates) which USI may obtain to refinance
          amounts outstanding hereunder, the terms of which, in the aggregate,
          are no less favorable to USI (taking into account both the term of any
          such facility as well as the interest rate).

2.   All other provisions of the Agreement shall remain in full force and
     effect.

     IN WITNESS WHEREOF, EDS and USI have caused this Amendment One to the
Agreement to be executed as of the effective date set forth above.

                   ELECTRONIC DATA SYSTEMS CORPORATION

                   By:        /s/ James E. Daley
                      ----------------------------------------------------------
                   Name:          James E. Daley
                        --------------------------------------------------------
                   Title:   Executive Vice President and Chief Financial Officer
                         -------------------------------------------------------

                   UNIGRAPHICS SOLUTIONS INC.

                   By:               /s/ Douglas E. Barnett
                      ----------------------------------------------------------
                   Name:                Douglas E. Barnett
                        --------------------------------------------------------
                   Title:   Vice President and Chief Financial Officer
                         -------------------------------------------------------<PAGE>

                                                                     EXHIBIT 4.4

               ORGANIZED UNDER THE LAWS OF THE STATE OF MARYLAND

NO. 1                                    Shares
                                ---------

                           PRENTISS PROPERTIES TRUST
                                         Shares
                                ---------
             Series D Cumulative Convertible Redeemable Preferred
            Shares of Beneficial Interest par value $.01 per share

THIS IS TO CERTIFY THAT Security Capital Preferred Growth Incorporated is the
owner of                                             fully paid and non-
         -------------------------------------------
assessable shares of the above Corporation transferable only on the books of the
Corporation by the holder hereof in person or by a duly authorized Attorney upon
surrender of this Certificate properly endorsed.

WITNESS, the seal of the Corporation and the Signatures of its duly authorized
officers.
DATED:  March    , 2001
              ---

Senior Vice President                             Secretary

                         [CORPORATE SEAL APPEARS HERE]

<PAGE>

          For Value Received,         hereby sell, assign and transfer unto
                              -------

--------------------------------------------------------------------------------
                                                              Shares represented
-------------------------------------------------------------
by the within Certificate and do hereby irrevocably constitute and appoint
                                                      Attorney to transfer the
-----------------------------------------------------
said Shares on the books of the within named Corporation with full power of
substitution in the premises.

     Dated
          ------------------------------------------------------------

          In presence of

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

     The Trust will furnish to any shareholder, on request and without charge, a
full statement of the information required by Section 8-203(d) of the
Corporations and Associations Articles of the Annotated Code of Maryland with
respect to the designations and any preferences, conversion and other rights,
voting powers, restrictions, limitations as to dividends and other
distributions, qualifications, and terms and conditions of redemption of the
shares  of each class of beneficial interest which the Trust has authority to
issue and, if the Trust is authorized to issue any preferred or special class in
series, (i) the differences in the relative rights and preferences between the
shares of each series to the extent set, and (ii) the authority of the Board of
Trustees to set such rights and preferences of subsequent series.  The foregoing
summary does not purport to be complete and is subject to and qualified in its
entirety by reference to the Amended and Restated Declaration of Trust of the
Trust, a copy of which will be sent without charge to each shareholder who
requests.  Such request must be made to the Secretary of the Trust at its
principal office.

     The Shares represented by this certificate are subject to restrictions on
transfer for the purpose of the Trust's maintenance of its status as a real
estate investment trust under the Internal Revenue Code of 1986, as amended (the
"Code").  Subject to certain further restrictions and except as provided in the
Amended and Restated Declaration of Trust of the Trust, no Person may (i)
Beneficially or Constructively Own Common Shares in excess of 8.5% (or such
other percentage as may be determined by the Board of Trustees) of the number of
outstanding Common Shares, (ii) Beneficially or Constructively Own Preferred
Shares of any series of Preferred Shares in excess of 9.8% of the number of
outstanding Preferred Shares of such series, (or such other percentage as may be
determined by the Board of Trustees), (iii) Beneficially Own Equity Shares that
would result in the Equity Shares being beneficially owned by fewer than 100
Persons (determined without reference to any rules of attribution), (iv)
Beneficially Own Equity Shares that would result in the Trust being "closely
held" under Section 856(h) of the Code, or (v) Constructively Own Equity Shares
that would cause the Trust to Constructively Own 10% or more of the ownership
interests in a tenant of the Trust's real property, within the meaning of
Section 856(d)(2)(B) of the Code.  Any Person who attempts to Beneficially or
Constructively Own shares of Equity Shares in excess of the above limitations
must immediately notify the Trust in writing.  If any restrictions above are
violated, the Equity Shares represented hereby will be transferred automatically
to a Share Trust and shall be designated Shares in Trust to a trustee of a trust
for the benefit of one or more charitable beneficiaries.  In addition, upon the
occurrence of certain events, attempted transfers in violation of the
restrictions described above may be void ab initio.  All capitalized terms in
this legend have the meanings defined in the Trust's Amended and Restated
Declaration of Trust, as the same may be further amended from time to time, a
copy of which, including the restrictions on transfer, will be sent without
charge to each shareholder who so requests.  Such requests may be made to the
secretary of the trust at its principal office or to the transfer agent.

     The Shares represented by this certificate have not been registered under
the Securities Act of 1933, as amended, or state securities laws and may not be
transferred except pursuant to a registration or an opinion of counsel
reasonably satisfactory to the Trust that such registration is not required.

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