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                                                                    EXHIBIT 4.02


                      FOURTH AMENDMENT TO CREDIT AGREEMENT

Harris Trust and Savings Bank
Chicago, Illinois

Ladies and Gentlemen:

     Reference is hereby made to that certain Credit Agreement (the "Credit
Agreement"), dated as of September 23, 1997, by and among Comshare, Incorporated
(the "Company") and Comshare Limited (the "Borrowing Subsidiary") (together the
"Borrowers") and Harris Trust and Savings Bank (the "Bank"). All capitalized
terms used herein without definition shall have the same meanings herein as such
terms have in the Credit Agreement.

     The Borrowers have requested that the Bank extend the Termination Date and
the Bank will do so under the terms and conditions set forth in this Amendment.

     1.   AMENDMENT.

     The definition of "Termination Date" appearing in Section 5 of the Credit
Agreement shall be amended and as so amended shall be restated to read as
follows:

               "Termination Date" means September 30, 2002, or such earlier
               date on which the Commitment is terminated in whole pursuant to
               Section 3.4, 9.2 or 9.3 hereof, or such later date to which the
               Termination Date is extended pursuant to Section 12.4 hereof

     2.   CONDITIONS PRECEDENT

     The effectiveness of this Amendment is subject to the satisfaction of all
of the following conditions precedent:

Amendment.

          (a) The Borrowers and the Bank shall have executed and delivered this
     Amendment

          (b) The Guarantors and each party signatory to that certain Debt
     Subordination Agreement dated September 23, 1997 shall have each executed
     and delivered to the Bank their consent to this Amendment in the forms set
     forth below.

          (c) Legal matters incident to the execution and delivery of this
     Amendment shall be satisfactory to the Bank and its counsel.

     3.   REPRESENTATIONS.

     In order to induce the Bank to execute and deliver this Amendment, the
Borrowers hereby represent to the Bank that as of the date hereof the
representations and warranties set forth in Section 6 of the Credit Agreement
are and shall be and remain true and correct (except that the


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representations contained in Section 6.5 shall be deemed to refer to the most
recent financial statements of the Borrowers delivered to the Bank) and, except
as waived herein, the Borrowers are in compliance with the terms and conditions
of the Credit Agreement and no Default or Event of Default has occurred and is
continuing under the Credit Agreement or shall result after giving effect to
this Amendment.

     4.   MISCELLANEOUS.

          4.1. The Borrowers heretofore executed and delivered to the Bank the
Security Agreement, Pledge Agreement and certain other Collateral Documents. The
Borrowers hereby acknowledge and agree that the Liens created and provided for
by the Collateral Documents continue to secure, among other things, the
Obligations arising under the Credit Agreement as amended hereby; and the
Collateral Documents and the rights and remedies of the Bank thereunder, the
obligations of the Borrowers thereunder, and the Liens created and provided for
thereunder remain in full force and effect and shall not be affected, impaired
or discharged hereby. Nothing herein contained shall in any manner affect or
impair the priority of the liens and security interests created and provided for
by the Collateral Documents as to the indebtedness which would be secured
thereby prior to giving effect to this Amendment.

          4.2. Except as specifically amended herein, the Credit Agreement shall
continue in full force and effect in accordance with its original terms.
Reference to this specific Amendment need not be made in the Credit Agreement,
the Note, or any other instrument or document executed in connection therewith,
or in any certificate, letter or communication issued or made pursuant to or
with respect to the Credit Agreement, any reference in any of such items to the
Credit Agreement being sufficient to refer to the Credit Agreement as amended
hereby.

          4.3. The Borrowers agree to pay on demand all costs and expenses of or
incurred by the Bank in connection with the negotiation, preparation, execution
and delivery of this Amendment, including the fees and expenses of counsel for
the Bank.

          4.4. This Amendment may be executed in any number of counterparts, and
by the different parties on different counterpart signature pages, all of which
taken together shall constitute one and the same agreement. Any of the parties
hereto may execute this Amendment by signing any such counterpart and each of
such counterparts shall for all purposes be deemed to be an original. This
Amendment shall be governed by the internal laws of the State of Illinois.


                           [SIGNATURE PAGE TO FOLLOW]


                                      -2-
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Dated as of this 31st day of October, 2000.


                                                 COMSHARE, INCORPORATED

                                                 By
                                                 Name  /s/ Kathryn Jeble
                                                       -----------------
                                                 Title SVP & CFO
                                                       -----------------


                                                 COMSHARE LIMITED

                                                 By
                                                 Name  /s/ Kathryn Jeble
                                                       -----------------
                                                 Title Director
                                                       -----------------

Accepted and agreed to as of the date last above written.


                                                 HARRIS TRUST AND SAVINGS BANK

                                                 By
                                                 Name  /s/ Kirby M. Law
                                                       -----------------
                                                 Title Vice President
                                                       -----------------





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                     GUARANTORS' ACKNOWLEDGEMENT AND CONSENT

     Each of the undersigned Guarantors heretofore executed and delivered to the
Bank a separate Guaranty Agreement each dated September 23, 1997. Each of the
undersigned hereby consent to the Fourth Amendment to Credit Agreement as set
forth above and confirm that its Guaranty Agreement and all of the
undersigned's obligations thereunder remain in full force and effect. Each of
the undersigned further agree that the consent of the undersigned to any further
amendments to the Credit Agreement shall not be required as a result of this
consent having been obtained, except to the extent, if any, required by the
Guaranty Agreement referred to above.

                                           COMSHARE (U.S.), INC.
                                           COMSHARE LIMITED (CANADA)
                                           COMSHARE HOLDINGS COMPANY

                                           By  /s/ Kathryn Jeble
                                               ------------------------
                                              Name:
                                                      -----------------
                                              Title:  Director
                                                      -----------------


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              SUBORDINATED CREDITORS' ACKNOWLEDGEMENT AND CONSENT

      Each of the undersigned heretofore executed in favor of the Bank a Debt
Subordination Agreement dated September 23, 1997.  Each of the undersigned
hereby consent to the Fourth Amendment to Credit Agreement as set forth above
and confirms that the Debt Subordination Agreement and all of the undersigned's
obligations thereunder remain in full force and effect.  Each of the
undersigned further agree that the consent of the undersigned to any further
amendments to the Credit Agreement shall not be required as a result of this
consent having been obtained, except to the extent, if any, required by the
Debt Subordination Agreement referred to above.



                                           COMSHARE, INCORPORATED
                                           COMSHARE LIMITED
                                           COMSHARE HOLDINGS COMPANY
                                           COMSHARE LIMITED

                                           By  /s/ Kathryn Jeble
                                               ------------------------
                                              Name:
                                                      -----------------
                                              Title:  Director
                                                      -----------------