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                                                                    EXHIBIT 10.1


          Confidential Materials omitted and filed separately with the
        Securities and Exchange Commission. Asterisks denote omissions.



                          FOURTH AMENDMENT TO PROGRESS
                     SOFTWARE APPLICATION PARTNER AGREEMENT

         FOURTH AMENDMENT to the Progress Software Corporation Application
Partner Agreement is effective as of April 1, 1998 ("Effective Date"), by and
between Progress Software Corporation, a Massachusetts corporation with its
principal place of business at 14 Oak Park, Bedford, Massachusetts 01730 ("PSC")
and Security Dynamics Inc., a Massachusetts corporation with its principal place
of business at 20 Crosby Drive, Bedford, Massachusetts 01730 ("AP").

         WHEREAS, PSC and AP entered into a Progress Software Application
Partner Agreement effective as of December 5, 1994 (the "Agreement"); and

         WHEREAS, PSC and AP previously amended the Agreement by entering into
the Progress Software Application Partner Agreement Addendum effective as of
December 5, 1994 (the "Addendum") and a subsequent amendment to the Agreement
dated as of October 19, 1995 (the "Amendment");

         WHEREAS, PSC and AP entered into a Second Amendment to the Agreement
dated as of November 29, 1995 (the "Second Amendment") which completely
superseded the terms and conditions of the earlier Addendum and Amendment and
specified new special pricing and distribution terms and conditions in an
Attachment A relating to certain PSC products distributed by AP or AP's
distributors in conjunction with AP's PROGRESS(R)-based applications; and

         WHEREAS, PSC and AP entered into a Third Amendment to the Agreement
dated as of November 15, 1996 (the "Third Amendment") specifying certain
additional modifications to the terms and conditions of the Agreement and
replacing the Attachment A incorporated by reference into the Second Amendment
with a new Attachment A including modified special pricing and distribution
terms and conditions relating to certain PSC products distributed by AP or AP's
distributors in conjunction with AP's PROGRESS(R)-based applications;

         WHEREAS, PSC and AP desire to make additional modifications to the
terms and conditions of the Agreement and to the special pricing and
distribution terms and conditions set forth in Attachment A to the Third
Amendment;

         NOW, THEREFORE, for good and valuable consideration, the receipt and
adequacy of which is hereby acknowledged, the parties hereto agree as follows:

1.       The terms and conditions of Attachment A to the Third Amendment
         (hereinafter referred to as "Attachment A") shall continue in force
         during the term of this Fourth Amendment subject to the following:

         A.       The purpose of Section 1 of Attachment A is to specify the PSC
                  products which AP has the right to distribute to accomplish
                  the AP customer configuration for AP's PROGRESS-based
                  application. The


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          Confidential Materials omitted and filed separately with the
        Securities and Exchange Commission. Asterisks denote omissions.



                  identification of the PSC products included in the AP customer
                  configuration was omitted from Section 1 of Attachment A.

                  AP represents that the PSC products AP has been deploying as
                  part of the AP customer configuration for AP's PROGRESS-based
                  application during the term of the Third Amendment consists of
                  the following PSC products: ProVISION, E/SQL, Enterprise
                  Database Server, Server Networking, Client Networking, or
                  subset thereof. During the term of this Fourth Amendment, the
                  PSC products which AP may deploy as part of the AP customer
                  configuration will continue to be limited to the PSC products
                  referenced above.

                  As part of PSC's development project code named "Sky Walker,"
                  PSC is developing a new version of the Enterprise Database
                  Server product. Section 1 of Attachment A specifies that AP
                  will be entitled to receive updates of the PSC products
                  included in the AP customer configuration as they become
                  available. The new version of the Enterprise Database Server,
                  once generally available, will be considered an "update" for
                  the purposes of Section 1 of Attachment A. If AP offers to
                  upgrade existing ACE Server application licenses by offering
                  to replace the Enterprise Database Server product with the new
                  version (once generally available), or otherwise offers to
                  upgrade the ACE Server application, and charges its AP
                  customers an upgrade fee for such upgrades, the upgrade fees
                  will be subject to the percentage royalty provisions set forth
                  in Sections 3 and 4 of Attachment A, as modified by paragraphs
                  (F) and (G) below, respectively.

         B.       During the term of this Fourth Amendment, the special pricing,
                  production, and distribution terms and conditions set forth in
                  Attachment A shall apply solely with respect to the PSC
                  products listed in paragraph (A) above distributed only in
                  conjunction with AP's ACE Server application or any future
                  releases of the ACE Server application known by any other name
                  which contain substantially the same functionality as the ACE
                  Server application.

         C.       Section 7 of Attachment A provided that PSC would grant AP a
                  development license, as defined therein, for the SINIX
                  operating system platform subject to a license fee of [**],
                  and a maintenance fee of [**] of such license fee. AP did not
                  purchase such development license for the SINIX operating
                  system platform during the term of the Third Amendment. PSC no
                  longer supports the development license on the SINIX operating
                  system platform, therefore, this option will no longer be
                  available to AP during the term of the Fourth Amendment.


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        Securities and Exchange Commission. Asterisks denote omissions.



         D.       Exhibit A to Attachment A specifies the generally available
                  operating system environments for the PSC products identified
                  in paragraph (A) above. The PSC products specified in
                  paragraph (A) above are no longer supported on the SINIX
                  operating system platform. The SINIX operating system shall be
                  deemed to be stricken from said Exhibit A.

         E.       The price list for AP's ACE Server application as set forth in
                  Section 2 of Attachment A has been updated by AP. A copy of
                  the current price list in effect as of January 1, 1998 is
                  attached hereto. All prices in the price list attached hereto
                  are in U.S. dollars. Section 2 of Attachment A also refers to
                  an Exhibit B containing AP's discount schedule for the ACE
                  Server application. AP has eliminated the discount schedule
                  set forth in said Exhibit B, and no longer has a standard
                  discount schedule for the ACE Server application. AP shall
                  notify PSC in writing of any changes made by AP to the ACE
                  Server price list and/or any new discount schedule(s)
                  established by AP from time to time during the term of this
                  Fourth Amendment.

         F.       Section 3 of Attachment A specifies the method for calculating
                  the license fee owed to PSC for each ACE Server license
                  deployed with certain PSC products, as described in paragraph
                  (A) above. The formula for calculating PSC's license fee shall
                  remain the same as set forth in Section 3 of Attachment A,
                  except that the royalty rate of [**] referenced in the first
                  paragraph of Section 3 of Attachment A shall be reduced to
                  [**]. Also, the royalty rate increase referenced at the end of
                  Section 3 of Attachment A as being an increase from [**] to
                  [**] shall be modified to reflect an increase from [**] to
                  [**]. The effective date of the license royalty rate reduction
                  described above shall be subject to the terms and conditions
                  set forth in paragraph (I) below.

         G.       Section 4 of Attachment A specifies the method for calculating
                  the maintenance fees due to PSC for each AP customer obtaining
                  a license to use PSC products in conjunction with AP's ACE
                  Server application, as well as certain terms and conditions
                  pertaining to the scope of maintenance services to be provided
                  by PSC in consideration of such maintenance fees. The terms
                  and conditions of Section 4 of Attachment A shall remain the
                  same except that the maintenance royalty rate of [**]
                  referenced in Section 4 of Attachment A shall be reduced to
                  [**]. The effective date of the maintenance royalty rate
                  reduction described above shall be subject to the terms and
                  conditions set forth in paragraph (I) below.


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        Securities and Exchange Commission. Asterisks denote omissions.



         H.       Section 5 of Attachment A specifies AP's reporting
                  requirements. The terms and conditions contained in said
                  Section 5 shall remain the same except that AP shall be
                  required to provide PSC with the required reports on a monthly
                  basis rather than a quarterly basis. The reports for each
                  month will be due by the thirtieth (30th) day of the following
                  month and shall cover copies of the ACE Server application
                  licensed, upgraded and/or maintenance collected directly by AP
                  or one of its authorized distributors or value-added resellers
                  during the month which is the subject of the report. Payment
                  in full for license and maintenance fees owed to PSC for the
                  prior month is due with these reports.

         I.       In accordance with Section 12 of Attachment A, AP paid to PSC
                  a non-refundable advance payment of $3.75 million. In exchange
                  for such payment, PSC provided AP with a $3.75 million
                  allowance to be used against license and initial maintenance
                  fees for deployment licenses incurred on or after the
                  effective date of Attachment A. Pursuant to said Section 12,
                  once AP completely used the $3.75 million allowance, the
                  royalty percentage rate used to calculate the deployment
                  license fees owed to PSC pursuant to Section 3 of Attachment A
                  was to increase from [**] to [**].

                  The above-mentioned royalty increase shall not occur upon
                  exhaustion of the $3.75 million allowance. AP shall pay to PSC
                  another nonrefundable advance payment in the amount of $6
                  million in accordance with the following payment schedule:

                           $1,650,000       due by May 31, 1998
                           $1,650,000       due by June 30, 1998
                           $1,700,000       due by July 31, 1998
                           $1,000,000       due by November 1, 1998

                  In exchange for such payment, PSC will provide AP with a $6
                  million allowance against license and maintenance fees for
                  deployment licenses subject to the following conditions:

                  (i)      If AP has a remaining balance of the $3.75 million
                           allowance as of the Effective Date of this Fourth
                           Amendment, then the license royalty rate of [**] and
                           the maintenance royalty rate of [**] originally
                           referenced in Sections 3 and 4 of Attachment A
                           respectively shall remain in effect until the $3.75
                           million allowance is completely exhausted.
                           Immediately thereafter, the $6 million allowance
                           shall be used to offset license and maintenance fees
                           for deployment licenses and the license royalty rate
                           referenced in Section 3 of Attachment A shall, in
                           accordance with paragraph (F) above, be reduced from
                           [**]

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        Securities and Exchange Commission. Asterisks denote omissions.



                           [**] to [**] and the maintenance royalty rate
                           referenced in Section 4 of Attachment A shall, in
                           accordance with paragraph (G) above, be reduced from
                           [**] to [**].

                  (ii)     If AP exhausted the $3.75 million allowance prior to
                           the Effective Date of this Fourth Amendment, PSC
                           shall, rather than invoicing AP for any excess
                           license and maintenance fees, reduce AP's $6 million
                           allowance by the amount of such fees. Notwithstanding
                           the foregoing, any license and maintenance fees owed
                           to PSC for copies of the ACE Server application
                           licensed or upgraded, or for maintenance collected,
                           prior to the Effective Date of this Fourth Amendment
                           shall be calculated using the license royalty rate of
                           [**] and the maintenance royalty rate of [**]
                           originally referenced in Sections 3 and 4 of
                           Attachment A, respectively. If AP exhausted the $3.75
                           million allowance as described in this subparagraph
                           (ii), then, as of the Effective Date of this Fourth
                           Amendment, the license royalty rate referenced in
                           Section 3 of Attachment A shall, in accordance with
                           paragraph (F) above, be reduced from [**] to [**] and
                           the maintenance royalty rate referenced in Section 4
                           of Attachment A shall, in accordance with paragraph
                           (G) above, be reduced from [**] to [**].

                  Once AP has completely used all of the $6 million allowance
                  mentioned above, the royalty percentage rate used to calculate
                  the deployment license fees owed to PSC under Section 3 of
                  Attachment A shall be increased from [**] to [**] for the
                  remainder of the term of this Fourth Amendment.

         J.       The provision set forth in Section 14 of Attachment A allowing
                  AP to use up to [**] of the pre-paid product/maintenance
                  allowance for paying the education service fees described in
                  said Section 14 shall not apply with respect to the prepayment
                  described in paragraph (I) above.

2.       The terms and conditions pertaining to the limit on PSC's liability
         under the Agreement shall remain the same as specified in Section 4 of
         the Third Amendment, except that the cap on PSC's aggregate liability
         under the Agreement shall be increased such that the limit is the
         greater of (a) [**] or (b) the total amount of royalties reported by AP
         to PSC for PSC products delivered to AP customers during the ninety day
         period immediately prior to the date the claim is made by AP.

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3.       The terms and conditions pertaining to the limit on AP's liability
         under the Agreement shall remain the same as specified in the second
         paragraph of Section 6 of the Second Amendment, except that the cap on
         AP's aggregate liability under the Agreement shall be increased such
         that the limit is the lesser of (a) the sum of the aggregate amounts
         paid by AP under this Agreement and any outstanding amounts owed by AP
         to PSC under this Agreement or (b) [**].

4.       The term of this Fourth Amendment shall commence as of the Effective
         Date defined above, and shall continue in force until the expiration
         date as specified in Section 6 of the Third Amendment.

5.       Except as may be modified or amended by this Fourth Amendment, the
         terms and conditions of the Agreement (as previously amended by the
         Third and Second Amendments thereto) shall remain in effect until the
         termination of the Agreement. No other modifications or additions are
         made to the Agreement. The Agreement, Second Amendment, Third Amendment
         and this Fourth Amendment constitutes the entire agreement between the
         parties with respect to the subject matter hereof. In the event of
         conflict among the terms and conditions of the Agreement, the Second
         Amendment, the Third Amendment or this Fourth Amendment, the order of
         precedence shall be: first, this Fourth Amendment, second, the Third
         Amendment, third, the Second Amendment (which completely superseded the
         earlier Addendum and Amendment) and fourth and finally, the Agreement.

         IN WITNESS WHEREOF, this Fourth Amendment has been executed under seal
for and on behalf of each of the parties hereto by their duly authorized
representative as of the date first set forth above.


PROGRESS SOFTWARE CORPORATION                         SECURITY DYNAMICS, INC.

By:  /s/ DAVID P. VESTY                               By:  /s/ A.W. COVIELLO JR.
     -----------------                                     ---------------------
Name:    David P. Vesty                               Name:    A.W. Coviello Jr.

Title:  Vice President                                Title:  COO

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