Document:

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                                                                     EXHIBIT 4.2

                                  DISCOVER BANK

                      Master Servicer, Servicer and Seller

                                       and

                         U.S. BANK NATIONAL ASSOCIATION

                                     Trustee

                       on behalf of the Certificateholders

                             FIRST AMENDMENT TO THE
                       SERIES SUPPLEMENT FOR SERIES 2001-2
                          dated as of January 16, 2001

                                       to

                         POOLING AND SERVICING AGREEMENT
                           Dated as of October 1, 1993

                                   Dated as of
                                 August 24, 2001

<PAGE>   2

          THIS FIRST AMENDMENT TO THE SERIES SUPPLEMENT FOR SERIES 2001-2 (the
"Amendment"), dated as of August 24, 2001, is entered into by and between
DISCOVER BANK (formerly Greenwood Trust Company), a Delaware banking
corporation, as Master Servicer, Servicer and Seller ("Discover Bank") and U.S.
BANK NATIONAL ASSOCIATION (formerly First Bank National Association, successor
trustee to Bank of America Illinois, formerly Continental Bank, National
Association), as Trustee (the "Trustee").

          WHEREAS, Discover Bank and the Trustee have entered into the SERIES
SUPPLEMENT FOR SERIES 2001-2 (the "Series Supplement"), dated as of January 16,
2001 with respect to the Series 2001-2 Certificates, pursuant to Section 6.06 of
that certain Pooling and Servicing Agreement (the "Pooling and Servicing
Agreement"), dated as of October 1, 1993, as amended, relating to Discover Card
Master Trust I; and

          WHEREAS, pursuant to subsection 13.01(a)(4) of the Pooling and
Servicing Agreement, Discover Bank and the Trustee desire to amend the
definition of "Maximum Class B Credit Enhancement Amount" in the Series Term
Sheet.

          NOW, THEREFORE, in consideration of the foregoing and the mutual
agreements herein contained, each party agrees as follows for the benefit of the
other parties and for the benefit of the Certificateholders:

          1. Definitions. Unless otherwise specified, capitalized terms used in
this Amendment shall have the same meanings ascribed to them in the Series
Supplement.

          2. Amendment to the definition of "Maximum Class B Credit Enhancement
             Amount".

             (a)  The definition for "Maximum Class B Credit Enhancement
                  Amount" is hereby amended and restated in its entirety to
                  read as follows:

             On any Distribution Date (a) prior to the making of an Effective
             Alternative Credit Support Election, the greater of (i)
             $11,578,950 and (ii) (x) if a Supplemental Credit Enhancement
             Event has not occurred, an amount equal to 7.5% of the Series
             Investor Interest as of the last day of the related Due Period,
             or (y) if a Supplemental Credit Enhancement Event has occurred,
             an amount equal to 8.0% of the Series Investor Interest as of the
             last day of the related Due Period, (b) subsequent to the making
             of an Effective Alternative Credit Support Election, the greater
             of (i) $11,578,950 and (ii) an amount equal to 12.5% of the
             Series Investor Interest as of the last day of the related Due
             Period, provided, however, that if an Amortization Event with
             respect to the Series established hereby occurs, the Maximum
             Class B Credit Enhancement Amount for each Distribution Date
             thereafter shall equal the Maximum Class B Credit

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               Enhancement Amount for the Distribution Date immediately
               preceding the occurrence of the Amortization Event; and provided,
               further, that if a Credit Enhancement Drawing has been made,
               until such time as the Available Class B Credit Enhancement
               Amount has been reinstated in an amount at least equal to the
               amount of such Credit Enhancement Drawing, the Maximum Class B
               Credit Enhancement Amount shall be the Maximum Class B Credit
               Enhancement Amount as of the date of such Credit Enhancement
               Drawing.

          3. Effect Upon the Series Supplement. Except as specifically set forth
herein, the Series Supplement shall remain in full force and effect and is
hereby ratified and confirmed.

          4. Counterparts. This Amendment may be executed in two or more
counterparts (and by different parties on separate counterparts), each of which
shall be an original, but all of which together shall constitute one and the
same instrument.

                                       2

<PAGE>   4

          IN WITNESS WHEREOF, Discover Bank and the Trustee have caused this
Amendment to be duly executed by their respective officers as of the day and
year first above written.

                                     DISCOVER BANK,
                                      as Master Servicer, Servicer and Seller

                                     By:    /s/ MICHAEL F. RICKERT
                                            -----------------------------------
                                     Name:  Michael F. Rickert
                                     Title: Vice President, Chief Accounting
                                            Officer and Treasurer

                                     U.S. BANK NATIONAL ASSOCIATION,
                                       as Trustee

                                     By:    /s/ PATRICIA M. CHILD
                                            -----------------------------------
                                     Name:  Patricia M. Child
                                     Title: Vice President

                                       3<PAGE>   1

                                                                     EXHIBIT 4.3

                                  DISCOVER BANK

                      Master Servicer, Servicer and Seller

                                       and

                         U.S. BANK NATIONAL ASSOCIATION

                                     Trustee

                       on behalf of the Certificateholders

                             FIRST AMENDMENT TO THE
                       SERIES SUPPLEMENT FOR SERIES 2001-3
                           dated as of March 15, 2001

                                       to

                         POOLING AND SERVICING AGREEMENT
                           Dated as of October 1, 1993

                                   Dated as of
                                 August 24, 2001

<PAGE>   2

                  THIS FIRST AMENDMENT TO THE SERIES SUPPLEMENT FOR SERIES
2001-3 (the "Amendment"), dated as of August 24, 2001, is entered into by and
between DISCOVER BANK (formerly Greenwood Trust Company), a Delaware banking
corporation, as Master Servicer, Servicer and Seller ("Discover Bank") and U.S.
BANK NATIONAL ASSOCIATION (formerly First Bank National Association, successor
trustee to Bank of America Illinois, formerly Continental Bank, National
Association), as Trustee (the "Trustee").

                  WHEREAS, Discover Bank and the Trustee have entered into the
SERIES SUPPLEMENT FOR SERIES 2001-3 (the "Series Supplement"), dated as of March
15, 2001 with respect to the Series 2001-3 Certificates, pursuant to Section
6.06 of that certain Pooling and Servicing Agreement (the "Pooling and Servicing
Agreement"), dated as of October 1, 1993, as amended, relating to Discover Card
Master Trust I; and

                  WHEREAS, pursuant to subsection 13.01(a)(4) of the Pooling and
Servicing Agreement, Discover Bank and the Trustee desire to amend the
definition of "Maximum Class B Credit Enhancement Amount" in the Series Term
Sheet.

                  NOW, THEREFORE, in consideration of the foregoing and the
mutual agreements herein contained, each party agrees as follows for the benefit
of the other parties and for the benefit of the Certificateholders:

                  1.       Definitions.  Unless otherwise specified, capitalized
terms used in this Amendment shall have the same meanings ascribed to them in
the Series Supplement.

                  2.       Amendment to the definition of "Maximum Class B
                           Credit Enhancement Amount".

                           (a)      The definition for "Maximum Class B Credit
                                    Enhancement Amount" is hereby amended and
                                    restated in its entirety to read as follows:

                           On any Distribution Date (a) prior to the making of
                           an Effective Alternative Credit Support Election, the
                           greater of (i) $7,894,740 and (ii) (x) if a
                           Supplemental Credit Enhancement Event has not
                           occurred, an amount equal to 7.5% of the Series
                           Investor Interest as of the last day of the related
                           Due Period, or (y) if a Supplemental Credit
                           Enhancement Event has occurred, an amount equal to
                           8.0% of the Series Investor Interest as of the last
                           day of the related Due Period, (b) subsequent to the
                           making of an Effective Alternative Credit Support
                           Election, the greater of (i) $7,894,740 and (ii) an
                           amount equal to 12.5% of the Series Investor Interest
                           as of the last day of the related Due Period,
                           provided, however, that if an Amortization Event with
                           respect to the Series established hereby occurs, the
                           Maximum Class B Credit Enhancement Amount for each
                           Distribution Date thereafter shall equal the Maximum
                           Class B Credit Enhancement

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                           Amount for the Distribution Date immediately
                           preceding the occurrence of the Amortization Event;
                           and provided, further, that if a Credit Enhancement
                           Drawing has been made, until such time as the
                           Available Class B Credit Enhancement Amount has been
                           reinstated in an amount at least equal to the amount
                           of such Credit Enhancement Drawing, the Maximum
                           Class B Credit Enhancement Amount shall be the
                           Maximum Class B Credit Enhancement Amount as of the
                           date of such Credit Enhancement Drawing.

                  3.       Effect Upon the Series Supplement.  Except as
specifically set forth herein, the Series Supplement shall remain in full force
and effect and is hereby ratified and confirmed.

                  4.       Counterparts.  This Amendment may be executed in two
or more counterparts (and by different parties on separate counterparts), each
of which shall be an original, but all of which together shall constitute one
and the same instrument.

                                       2
<PAGE>   4

                  IN WITNESS WHEREOF, Discover Bank and the Trustee have caused
this Amendment to be duly executed by their respective officers as of the day
and year first above written.

                                DISCOVER BANK,
                                   as Master Servicer, Servicer and Seller

                                By:   /s/ MICHAEL F. RICKERT
                                     -------------------------------------------
                                Name:   Michael F. Rickert
                                Title:  Vice President, Chief Accounting Officer
                                        and Treasurer

                                U.S. BANK NATIONAL ASSOCIATION,
                                  as Trustee

                                By:  /s/ PATRICIA M. CHILD
                                    --------------------------------------------
                                Name:   Patricia M. Child
                                Title:  Vice President

                                       3

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