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                                  EXHIBIT 10.31
                                  -------------

                       THIRD AMENDMENT TO CREDIT AGREEMENT
                       -----------------------------------


     THIRD AMENDMENT (this "Amendment"), dated as of March 27, 1997, among
Computervision Corporation (the "Borrower"), a Delaware corporation, the
financial institutions listed on the signature pages hereto, Bankers Trust
Company, as Agent and Fleet Bank of Massachusetts, N.A., as Co-Agent under the
Credit Agreement referred to below. All capitalized terms used herein and not
otherwise defined shall have the respective meanings provided such terms in the
Credit Agreement referred to below.

                              W I T N E S S E T H:
                              --------------------

     WHEREAS, the Borrower, various lending institutions (the "Banks"), and
Bankers Trust Company, as Agent, are parties to a Credit Agreement dated as of
November 17, 1995 (as amended, modified or supplemented through the date hereof,
the "Credit Agreement"); and

     WHEREAS, the parties hereto wish to amend the Credit Agreement as herein
provided:

     NOW, THEREFORE, it is agreed:

     1.   Section 1.01(A) of the Credit Agreement shall be amended by (a) 
deleting the word "and" at the end of clause (iii) thereof and inserting a comma
in lieu thereof, (b) inserting a semi-colon at the end of clause (iv) and the
words "and thereafter" and (c) inserting the following new clause (v):

     "    (v)    shall not exceed for all Banks at any time outstanding that 
     aggregate principal amount which, when combined with the amount of all
     Swingline Loans then outstanding and the Letter of Credit Outstandings
     (exclusive of Swingline Loans and Unpaid Drawings which are repaid with the
     proceeds of, and simultaneously with the incurrence of, such Revolving
     Loans) at such time, an amount equal to (I) at any time prior to the
     Borrowing Base Amendment Date, $18,800,000 and (II) at any time on and
     after the Borrowing Base Amendment Date, the lesser of (a) the Borrowing
     Base then in effect and (b) the Total Commitment at such time (after giving
     effect to any reductions to the Total Commitment on such date)."

     2.   Section 1.01(B)(a) of the Credit Agreement shall be amended by 
deleting clause (iii) thereof in its entirety and inserting in lieu thereof the
following new clause (iii):

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     "    (iii)  shall not exceed in aggregate principal amount at any time
     outstanding, when combined with the aggregate principal amount of all
     Revolving Loans then outstanding and the Letter of Credit Outstandings
     (exclusive of Revolving Loans and Unpaid Drawings which are repaid with the
     proceeds of, and simultaneously with the incurrence of, such Swingline
     Loans) at such time, an amount equal to (I) at any time prior to the
     Borrowing Base Amendment Date, $18,800,000 and (II) at any time on and
     after the Borrowing Base Amendment Date, the lesser of (a) the Borrowing
     Base then in effect and (b) the Total Commitment at such time (after giving
     effect to any reductions to the Total Commitment on such date)."

     3.   Section 1.01(B)(b) of the Credit Agreement shall be amended by 
deleting clause (v) thereof in its entirety and inserting in lieu thereof the
following new clause (v):

     "    (v)    any reduction in the Total Commitment or the Borrowing Base 
     after any such Swingline Loans were made."

     4.   Section 2.01(b)(i) of the Credit Agreement shall be amended by 
deleting clause (y) contained therein in its entirety and inserting in lieu
thereof the following new clause (y):

     "    (y)    when added to the aggregate principal amount of all Loans then
     outstanding, an amount equal to (I) at any time prior to the Borrowing Base
     Amendment Date, $18,800,000 and (II) at any time on and after the Borrowing
     Base Amendment Date, the lesser of (a) the Borrowing Base then in effect
     and (b) the Total Commitment at such time (after giving effect to any
     reductions to the Total Commitment on such date)."

     5.   Section 4.02 of the Credit Agreement shall be amended by deleting 
clause (A) in its entirety and inserting the following new clause (A) in lieu
thereof:

     "    (A)    REQUIREMENTS: If the sum of (i) the aggregate outstanding 
     principal amount of Revolving Loans and Swingline Loans (after giving
     effect to all other repayments thereof on such date) plus (ii) the Letter
     of Credit Outstandings on such date exceeds an amount equal to (I) at any
     time prior to the Borrowing Base Amendment Date, $18,800,00 and (II) at any
     time on and after the Borrowing Base Amendment Date, the lesser of (a) the
     Borrowing Base then in effect and (b) the Total Commitment as then in
     effect, the Borrower shall repay on such date the principal of Swingline
     Loans, and to the extent such Swingline Loans are insufficient, Revolving
     Loans, in an aggregate amount equal to such excess. If, after giving effect
     to the prepayment of all outstanding Swingline Loans and 

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     Revolving Loans, the aggregate amount of Letter of Credit Outstandings
     exceeds an amount equal to (I) at any time prior to the Borrowing Base
     Amendment Date, $18,800,000 and (II) at any time on and after the Borrowing
     Base Amendment Date, the lesser of (a) the Borrowing Base then in effect
     and (b) the Total Commitment as then in effect, the Borrower agrees to pay
     to the Agent an amount in cash and/or Cash Equivalents equal to such excess
     and the Agent shall hold such payment as security for the obligations of
     the Borrower hereunder pursuant to a cash collateral agreement to be
     entered into in form and substance satisfactory to the Agent (which shall
     permit certain investments in Cash Equivalents satisfactory to the Agent,
     until the proceeds are applied to the secured obligations).

     6.   Section 5.02(A) of the Credit Agreement shall be amended by inserting
the following new clause (c):

     "    (c)    INITIAL BORROWING BASE CERTIFICATE. On the Borrowing Base 
     Amendment Date, the Borrower shall have delivered to the Agent the initial
     Borrowing Base Certificate."

     7.   Section 7.01 of the Credit Agreement shall be amended by inserting the
following new clauses (i) and (j):

     "    (i)    MONTHLY REPORT. Promptly, and in any event within 10 Business 
     Days of the end of each calendar month, an accounts receivable aging
     categorized by geographical region and a summary of all outstanding
     payables."

     "    (j)    BORROWING BASE CERTIFICATE. Once the Borrowing Base Amendment 
     Date has occurred, not later than 12:00 Noon (New York time) on the seventh
     Business Day after the end of each fiscal month, a completed Borrowing Base
     Certificate determined as of the last day of such fiscal month."

     8.   Section 8.09 of the Credit Agreement is hereby amended by deleting 
such Section in its entirety and inserting in lieu thereof the following new
Section 8.09:

     "    8.09   MINIMUM CONSOLIDATED EBITDA. The Borrower will not permit
     Consolidated EBITDA for any Test Period ending closest to the date set
     forth below to be less than the amount set forth opposite such date:




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                 Date                                  Amount
                 ----                                  ------

          December 31, 1995                        $ 86,000,000
          March 31, 1996                             86,500,000
          June 30, 1996                              86,500,000
          September 30, 1996                         86,500,000
          December 31, 1996                          86,200,000
          March 31, 1997                             69,800,000
          June 30, 1997                              68,800,000
          September 30, 1997                         71,100,000
          December 31, 1997                          84,400,000
          March 31, 1998                            115,000,000
          June 30, 1998                              95,000,000
          September 30, 1998                         95,000,000
          December 31, 1998                         100,000,000"

     9.   Section 8.10 of the Credit Agreement is hereby amended by deleting 
such Section in its entirety and inserting in lieu thereof the following new
Section 8.10:

     "    8.10   LEVERAGE RATIO. The Borrower will not permit the Leverage Ratio
     determined as at the end of any Test Period ending closest to the date set
     forth below to be more than the ratio set forth opposite such date:

                 Date                                  Ratio
                 ----                                  -----

          March 31, 1996                              5.75:1
          June 30, 1996                               5.00:1
          September 30, 1996                          4.50:1
          December 31, 1996                           4.25:1
          March 31, 1997                              6.02:1
          June 30, 1997                               5.19:1
          September 30, 1997                          4.76:1
          December 31, 1997                           3.51:1
          March 31, 1998                              3.50:1
              and each fiscal quarter thereafter."

     10.  Section 8.11 of the Credit Agreement is hereby amended by deleting 
such Section in its entirety and inserting in lieu thereof the following new
Section 8.11:

     "    8.11   FIXED CHARGE COVERAGE RATIO. The Borrower will not permit the 
     Fixed Charge Coverage Ratio for any Test Period ending 


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     closest to the date set forth below to be less than the ratio set forth
     opposite such date:


                 Date                                  Ratio
                 ----                                  -----

          March 31, 1996                              1.00:1
          June 30, 1996                               1.05:1
          September 30, 1996                          1.10:1
          December 31, 1996                           1.10:1
          March 31, 1997                              1.00:1
          June 30, 1997                               1.00:1
          September 30, 1997                          1.00:1
          December 31, 1997                           1.07:1
          March 31, 1998                              1.20:1
          June 30, 1998                               1.20:1
          September 30, 1998                          1.25:1
          December 31, 1998                           1.30:1"

     11.  Section 10 of the Credit Agreement shall be amended by inserting the
following new definition in appropriate alphabetical order:

          "Borrowing Base" shall have the meaning provided in the Borrowing Base
     Amendment.

          "Borrowing Base Amendment" shall be an amendment to this Credit
     Agreement executed by the Borrower and the Required Banks, which inter
     alia, shall define the Borrowing Base on a mutually agreeable basis.

          "Borrowing Base Amendment Date" shall mean the date on which the
     Borrowing Base Amendment becomes effective in accordance with its terms, it
     being understood that one condition to such effectiveness shall be the
     delivery of a Borrowing Base Certificate dated as of such effective date.

          "Borrowing Base Certificate" shall have the meaning provided in the
     Borrowing Base Amendment.

     12.  Section 10 of the Credit Agreement shall be further amended by 
deleting the period at the end of the definition of "Consolidated EBITDA" and
inserting the following clause in lieu thereof:

     "and adjusted by adding, (i) $19,500,000, for the Test Period ending
     December 31, 1996; (ii) $26,500,000, for the Test Period ending March 31,
     1997; (iii) $26,500,000, for the Test Period ending June 30, 1997; (iv)




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     $26,500,000, for the Test Period ending September 30, 1997; and (v)
     $7,000,000, for the Test Period ending December 31, 1997."

     13.  The Borrower hereby agrees to pay to the Agent for distribution to 
each Bank which executes this Amendment, a fee equal to 1/8 of 1% of the
aggregate Commitment of such Bank immediately prior to the Amendment Effective
Date.

     14.  The Borrower hereby agrees to cooperate in good faith with the Agent
and the Banks with the intention of formulating the definition of Borrowing Base
and having the Borrowing Base Amendment Date occur as soon as reasonably
practical after April 1, 1997. The Borrower hereby agrees to continue to file a
quarterly information statement of Form 10-Q every fiscal quarter and each such
Form 10-Q shall have attached as an exhibit an auditor's review report (which
shall not include any exceptions). Until the Borrowing Base Amendment Date, an
Event of Default will result from the failure of the Borrower to file a form
10-Q complying with the requirements of the preceding sentence. An Event of
Default will exist if the Borrowing Base Amendment Date has not occurred on or
prior to April 1, 1998.

     15.  In order to induce the Banks to enter into this Amendment, the 
Borrower hereby (i) makes each of the representations, warranties and agreements
contained in the Credit Agreement as though made on the Amendment Effective
Date, unless stated to relate to a specific earlier date, in which case such
representations and warranties shall be true and correct in all material
respects as of such earlier date and (ii) represents and warrants that there
exists no Default or Event of Default, in each case on the Amendment Effective
Date (as hereinafter defined), after giving effect to this Amendment.

     16.  This Amendment is limited as specified and shall not constitute a
modification, acceptance or waiver of any other provision of the Credit
Agreement.

     17.  This Amendment may be executed in any number of counterparts and by 
the different parties hereto on separate counterparts, each of which
counterparts when executed and delivered shall be an original, but all of which
shall together constitute one and the same instrument. A complete set of
counterparts shall be lodged with the Borrower and the Agent.

     18.  THIS AMENDMENT AND THE RIGHTS AND OBLIGATIONS OF THE PARTIES HEREUNDER
SHALL BE CONSTRUED IN ACCORDANCE WITH AND GOVERNED BY THE LAW OF THE STATE OF
NEW YORK.




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     19.  This amendment shall become effective on the date (the "Amendment
Effective Date") when the Borrower and the Required Banks shall have signed a
counterpart hereof (whether the same or different counterparts) and shall have
delivered (including by way of facsimile transmission) the same to the Agent.

     20.  From and after the Amendment Effective Date, all references in the
Credit Agreement and each of the other Credit Documents shall be deemed to be
references to the Credit Agreement as modified hereby.

                             * * * * * * * * * * * *
















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     IN WITNESS WHEREOF, each of the parties hereto has caused this Third
Amendment to be duly executed and delivered as of the date first above written.


                                   COMPUTERVISION CORPORATION


                                   By: /s/ James E. Hayden
                                   -----------------------
                                   Title: Vice  President, Corporate Controller


                                   BANKERS TRUST COMPANY,
                                   Individually and as Agent


                                   By: /s/ Tim Morris
                                   ------------------
                                   Title:V.P.


                                   BANK POLSKA KASA OPIEKI, S.A.,
                                   NEW YORK BRANCH


                                   By: /s/ Harvey Winter
                                   ---------------------
                                   Title:Vice President


                                   FLEET BANK OF MASSACHUSETTS,
                                   N.A.,
                                   Individually and as Co-Agent


                                   By: /s/ Derrick Upton
                                   ---------------------
                                   Title:Assistant Vice President




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