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Exhibit 4.1 EXECUTION COPY MERRILL LYNCH MORTGAGE INVESTORS, INC., Depositor WILSHIRE CREDIT CORPORATION, Servicer and U.S. BANK NATIONAL ASSOCIATION, Trustee ---------- POOLING AND SERVICING AGREEMENT Dated as of March 1, 2007 ---------- SPECIALTY UNDERWRITING AND RESIDENTIAL FINANCE TRUST MORTGAGE

Mortgage Agreement

Exhibit 4.1 EXECUTION COPY MERRILL LYNCH MORTGAGE INVESTORS, INC., Depositor WILSHIRE CREDIT CORPORATION, Servicer and U.S. BANK NATIONAL ASSOCIATION, Trustee ---------- POOLING AND SERVICING AGREEMENT Dated as of March 1, 2007 ---------- SPECIALTY UNDERWRITING AND RESIDENTIAL FINANCE TRUST MORTGAGE | Document Parties: MERRILL LYNCH MORTGAGE INVESTORS, INC | US BANK NATIONAL ASSOCIATION | WILSHIRE CREDIT CORPORATION You are currently viewing:
This Mortgage Agreement involves

MERRILL LYNCH MORTGAGE INVESTORS, INC | US BANK NATIONAL ASSOCIATION | WILSHIRE CREDIT CORPORATION

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Title: Exhibit 4.1 EXECUTION COPY MERRILL LYNCH MORTGAGE INVESTORS, INC., Depositor WILSHIRE CREDIT CORPORATION, Servicer and U.S. BANK NATIONAL ASSOCIATION, Trustee ---------- POOLING AND SERVICING AGREEMENT Dated as of March 1, 2007 ---------- SPECIALTY UNDERWRITING AND RESIDENTIAL FINANCE TRUST MORTGAGE
Governing Law: New York     Date: 4/10/2007
Law Firm: Dechert    

Exhibit 4.1 EXECUTION COPY MERRILL LYNCH MORTGAGE INVESTORS, INC., Depositor WILSHIRE CREDIT CORPORATION, Servicer and U.S. BANK NATIONAL ASSOCIATION, Trustee ---------- POOLING AND SERVICING AGREEMENT Dated as of March 1, 2007 ---------- SPECIALTY UNDERWRITING AND RESIDENTIAL FINANCE TRUST MORTGAGE, Parties: merrill lynch mortgage investors  inc , us bank national association , wilshire credit corporation
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<PAGE>

                                                                     Exhibit 4.1

                                                                  EXECUTION COPY

                     MERRILL LYNCH MORTGAGE INVESTORS, INC.,
                                     Depositor

                          WILSHIRE CREDIT CORPORATION,
                                    Servicer

                                       and

                         U.S. BANK NATIONAL ASSOCIATION,
                                      Trustee

                                   ----------

                         POOLING AND SERVICING AGREEMENT
                            Dated as of March 1, 2007

                                   ----------

              SPECIALTY UNDERWRITING AND RESIDENTIAL FINANCE TRUST
            MORTGAGE LOAN ASSET-BACKED CERTIFICATES, SERIES 2007-AB1

<PAGE>


                                TABLE OF CONTENTS

<TABLE>
<CAPTION>
                                                                             PAGE
                                                                            ----
<S>                                                                          <C>
ARTICLE I DEFINITIONS....................................................      12

ARTICLE II CONVEYANCE OF MORTGAGE LOANS; REPRESENTATIONS AND WARRANTIES..      61
   SECTION 2.01.   Conveyance of Mortgage Loans...........................      61
   SECTION 2.02.   Acceptance by Trustee of the Mortgage Loans............      64
   SECTION 2.03.   Representations, Warranties and Covenants of the
                  Depositor..............................................      65
   SECTION 2.04.   Representations and Warranties of the Servicer.........      68
   SECTION 2.05.   Substitutions and Repurchases of Mortgage Loans Which
                  Are Not "Qualified Mortgages"..........................      70
   SECTION 2.06.   Authentication and Delivery of Certificates............      70
   SECTION 2.07.   REMIC Elections........................................      70
   SECTION 2.08.   Covenants of the Servicer..............................      75
   SECTION 2.09.   [RESERVED].............................................      75
   SECTION 2.10.   [RESERVED].............................................      75
    SECTION 2.11.   Permitted Activities of the Issuing Entity.............      75
   SECTION 2.12.   Qualification of Special Purpose Entity................      76
   SECTION 2.13.   Depositor Notification of NIM Notes....................      76

ARTICLE III ADMINISTRATION AND SERVICING OF MORTGAGE LOANS...............      76
   SECTION 3.01.   Servicer to Service Mortgage Loans.....................      76
   SECTION 3.02.   Servicing and Subservicing; Enforcement of the
                  Obligations of Servicer................................      78
   SECTION 3.03.   Rights of the Depositor and the Trustee in Respect of
                  the Servicer...........................................      78
   SECTION 3.04.   Trustee to Act as Servicer.............................      79
   SECTION 3.05.   Collection of Mortgage Loan Payments; Collection
                  Account; Certificate Account...........................      79
   SECTION 3.06.   Collection of Taxes, Assessments and Similar Items;
                  Escrow Accounts........................................      83
   SECTION 3.07.   Access to Certain Documentation and Information
                  Regarding the Mortgage Loans...........................      83
   SECTION 3.08.   Permitted Withdrawals from the Collection Account and
                  Certificate Account....................................      83
   SECTION 3.09.   [RESERVED].............................................      85
   SECTION 3.10.   Maintenance of Hazard Insurance........................      85
   SECTION 3.11.   Enforcement of Due-On-Sale Clauses; Assumption
                  Agreements.............................................      86
</TABLE>


                                        i

<PAGE>


                                TABLE OF CONTENTS
                                   (continued)

<TABLE>
<CAPTION>
                                                                            PAGE
                                                                            ----
<S>                                                                           <C>
   SECTION 3.12.   Realization Upon Defaulted Mortgage Loans;
                  Determination of Excess Proceeds.......................      87
   SECTION 3.13.   Trustee to Cooperate; Release of Mortgage Files........      91
   SECTION 3.14.   Documents Records and Funds in Possession of Servicer
                  to be Held for the Trustee.............................      93
   SECTION 3.15.   Servicing Compensation.................................      93
   SECTION 3.16.   Access to Certain Documentation........................      93
   SECTION 3.17.   Annual Statement as to Compliance......................      94
   SECTION 3.18.   Assessment of Compliance; Accountant's Attestation.....      94
    SECTION 3.19.   Subordination Liens....................................      96
   SECTION 3.20.   Periodic Filings.......................................      97
   SECTION 3.21.   Indemnification by Trustee.............................     101
   SECTION 3.22.   Indemnification by Servicer............................     101
   SECTION 3.23.   Prepayment Charge Reporting Requirements...............     102
   SECTION 3.24.   Statements to Trustee..................................     102
   SECTION 3.25.   Further Indemnification by the Servicer................     102
   SECTION 3.26.   Solicitation...........................................     103
   SECTION 3.27.   Existing Servicing Agreement...........................     103
   SECTION 3.28.   High Cost Mortgage Loans...............................     103
   SECTION 3.29.   [RESERVED].............................................     103

ARTICLE IV DISTRIBUTIONS.................................................     103
   SECTION 4.01.   Advances...............................................     103
   SECTION 4.02.   Reduction of Servicing Compensation in Connection with  
                  Prepayment Interest Shortfalls.........................     103
   SECTION 4.03.   Distributions on the REMIC Interests...................     104
   SECTION 4.04.   Distributions..........................................     104
   SECTION 4.05.   Monthly Statements to Certificateholders...............     104
                                                                         
ARTICLE V THE CERTIFICATES...............................................     118
   SECTION 5.01.   The Certificates.......................................     118
   SECTION 5.02.   Certificate Register; Registration of Transfer and      
                  Exchange of Certificates...............................     119
   SECTION 5.03.   Mutilated, Destroyed, Lost or Stolen Certificates......     123
   SECTION 5.04.   Persons Deemed Owners..................................     123
</TABLE>


                                        ii

<PAGE>

                                TABLE OF CONTENTS
                                   (continued)

<TABLE>
<CAPTION>
                                                                            PAGE
                                                                             ----
<S>                                                                          <C>
   SECTION 5.05.   Access to List of Certificateholders' Names and         
                  Addresses..............................................     123
   SECTION 5.06.   Book-Entry Certificates................................     124
   SECTION 5.07.   Notices to Depository..................................     125
   SECTION 5.08.   Definitive Certificates................................     125
   SECTION 5.09.   Maintenance of Office or Agency........................     125
   SECTION 5.10.   Authenticating Agent...................................     125
                                                                         
ARTICLE VI THE DEPOSITOR AND THE SERVICER................................     126
   SECTION 6.01.   Respective Liabilities of the Depositor and the         
                  Servicer...............................................     126
   SECTION 6.02.   Merger or Consolidation of the Depositor or the         
                  Servicer...............................................     126
   SECTION 6.03.   Limitation on Liability of the Depositor, the Servicer  
                  and Others.............................................     127
   SECTION 6.04.   Limitation on Resignation of Servicer..................     127
   SECTION 6.05.   Errors and Omissions Insurance; Fidelity Bonds.........     128
                                                                          
ARTICLE VII DEFAULT; TERMINATION OF SERVICER.............................     128
   SECTION 7.01.   Events of Default......................................     128
   SECTION 7.02.   [RESERVED].............................................     130
   SECTION 7.03.   Trustee to Act; Appointment of Successor...............     130
   SECTION 7.04.   Notification to Certificateholders.....................     131
                                                                         
ARTICLE VIII CONCERNING THE TRUSTEE......................................     131
   SECTION 8.01.   Duties of Trustee......................................     131
   SECTION 8.02.   Certain Matters Affecting the Trustee..................     132
   SECTION 8.03.   Trustee Not Liable for Mortgage Loans..................     134
   SECTION 8.04.   Trustee May Own Certificates...........................     134
   SECTION 8.05.   Trustee's Fees.........................................     134
   SECTION 8.06.   Indemnification of Trustee; Expenses...................     134
   SECTION 8.07.   Eligibility Requirements for Trustee...................     135
   SECTION 8.08.   Resignation and Removal of Trustee.....................     135
   SECTION 8.09.   Successor Trustee......................................     136
   SECTION 8.10.   Merger or Consolidation of Trustee.....................     137
   SECTION 8.11.   Appointment of Co-Trustee or Separate Trustee..........     137
   SECTION 8.12.   Tax Matters............................................      138
                                                                         
ARTICLE IX TERMINATION...................................................     140
   SECTION 9.01.   Termination upon Liquidation or Repurchase of all       
                  Mortgage Loans.........................................     140
   SECTION 9.02.   Final Distribution on the Certificates.................     142
</TABLE>


                                      iii

<PAGE>

                                TABLE OF CONTENTS
                                    (continued)

<TABLE>
<CAPTION>
                                                                            PAGE
                                                                            ----
<S>                                                                           <C>
   SECTION 9.03. Additional Termination Requirements.....................     143
                                                                         
ARTICLE X MISCELLANEOUS PROVISIONS.......................................     144
   SECTION 10.01. Amendment..............................................     144
   SECTION 10.02. Counterparts...........................................     146
   SECTION 10.03. Governing Law..........................................     146
   SECTION 10.04. Intention of Parties...................................     146
   SECTION 10.05. Notices................................................     147
   SECTION 10.06. Severability of Provisions.............................      148
   SECTION 10.07. Assignment.............................................     148
   SECTION 10.08. Limitation on Rights of Certificateholders.............     148
   SECTION 10.09. Inspection and Audit Rights............................     149
   SECTION 10.10. Certificates Nonassessable and Fully Paid..............     149
   SECTION 10.11. [RESERVED].............................................     149
   SECTION 10.12. [RESERVED].............................................     149
   SECTION 10.13. Third Party Rights.....................................     149
   SECTION 10.14. Assignment; Sales; Advance Facilities..................     149
</TABLE>


                                       iv

<PAGE>

EXHIBIT A    FORMS OF OFFERED CERTIFICATES
EXHIBIT B    MORTGAGE LOAN SCHEDULE - MORTGAGE POOL
EXHIBIT C-1 [RESERVED]
EXHIBIT C-2 [RESERVED]
EXHIBIT D    FORM OF TRUSTEE CERTIFICATION
EXHIBIT E-1 FORM OF TRANSFEREE'S LETTER AND AFFIDAVIT
EXHIBIT E-2 FORM OF TRANSFEROR'S AFFIDAVIT
EXHIBIT F    FORM OF TRANSFEROR CERTIFICATE FOR CLASS P AND CLASS C CERTIFICATES
EXHIBIT G    FORM OF INVESTMENT LETTER
EXHIBIT H    FORM OF RULE 144A INVESTMENT LETTER
EXHIBIT I    REQUEST FOR RELEASE OF DOCUMENTS
EXHIBIT J    FORM OF POWER OF ATTORNEY
EXHIBIT K    FORM OF OFFICER'S CERTIFICATE OF TRUSTEE
EXHIBIT L    FORM OF OFFICER'S CERTIFICATE OF SERVICER
EXHIBIT M    [RESERVED]
EXHIBIT N    FORM OF AUCTION PROCEDURES
EXHIBIT O-1 FORM OF CLASS A-1 CORRIDOR CONTRACT
EXHIBIT O-2 FORM OF CLASS A-2 CORRIDOR CONTRACT
EXHIBIT O-3 FORM OF SUBORDINATE CERTIFICATE CORRIDOR CONTRACT
EXHIBIT O-4 FORM OF CREDIT SUPPORT ANNEX FOR CORRIDOR CONTRACTS
EXHIBIT P    [RESERVED]
EXHIBIT Q    FORM OF ASSESSMENT OF COMPLIANCE
EXHIBIT R    SERVICING CRITERIA TO BE ADDRESSED
EXHIBIT S    FORM OF SARBANES-OXLEY CERTIFICATION
EXHIBIT T    FORM OF ITEM 1123 CERTIFICATION OF SERVICER
EXHIBIT U-1 FORM OF SWAP AGREEMENT
EXHIBIT U-2 FORM OF CREDIT SUPPORT ANNEX FOR THE SWAP AGREEMENT
SCHEDULE V   ITEMS FOR FORM 8-K
SCHEDULE W   ITEMS FOR FORM 10-D
SCHEDULE X   ITEMS FOR FORM 10-K
<PAGE>

     POOLING AND SERVICING AGREEMENT, dated as of March 1, 2007 (the
"Agreement"), among MERRILL LYNCH MORTGAGE INVESTORS, INC., a Delaware
corporation, as depositor (the "Depositor"), WILSHIRE CREDIT CORPORATION, a
Nevada corporation, as servicer (the "Servicer"), and U.S. BANK NATIONAL
ASSOCIATION, a national banking association, as trustee (the "Trustee").

     The Depositor is the owner of the Trust Fund that is hereby conveyed to the
Trustee in return for the Certificates. The Trust Fund for federal income tax
purposes will consist of (i) three real estate mortgage investment conduits in a
tiered structure, (ii) the right to receive the payments distributable to the
Class P Certificates pursuant to Section 4.04(b)(i) hereof, (iii) each Corridor
Contract and the Corridor Contract Account, (iv) the grantor trusts described in
Section 2.07 hereof and (v) the Supplemental Interest Trust, which in turn will
hold the Swap Agreement. The SWAP REMIC will consist of all of the assets
constituting the Trust Fund (other than the assets described in clauses (ii),
(iii), (iv) and (v) above, other than the SWAP REMIC Regular Interests and other
than the Lower Tier REMIC Regular Interests) and will be evidenced by the SWAP
REMIC Regular Interests (which will be uncertificated and will represent the
"regular interests" in the SWAP REMIC) and the Class SWR Interest as the single
"residual interest" in the SWAP REMIC. The Lower Tier REMIC will consist of SWAP
REMIC Regular Interests and will be evidenced by the Lower Tier REMIC Regular
Interests (which will be uncertificated and will represent the "regular
interests" in the Lower Tier REMIC) and the Class LTR Interest as the single
"residual interest" in the Lower Tier REMIC. The Trustee will hold the Lower
Tier REMIC Regular Interests. The Upper Tier REMIC will consist of the Lower
Tier REMIC Regular Interests and will be evidenced by the REMIC Regular
Interests (which will represent the "regular interests" in the Upper Tier REMIC)
and the Residual Interest as the single "residual interest" in the Upper Tier
REMIC. The Class R Certificate will represent beneficial ownership of the Class
SWR Interest, the Class LTR Interest and the Residual Interest. The "latest
possible maturity date" for federal income tax purposes of all interests created
hereby will be the Latest Possible Maturity Date.

     All covenants and agreements made by the Sponsor in the Sale Agreement and
by the Depositor and the Trustee herein with respect to the Mortgage Loans and
the other property constituting the Trust Fund are for the benefit of the
Holders from time to time of the Certificates.

THE SWAP REMIC

The following table sets forth the designations, initial principal balances and
interest rates for each interest in the SWAP REMIC:

<TABLE>
<CAPTION>
Class      Initial Principal Balance    Interest Rate
-----      -------------------------    -------------
<S>        <C>                          <C>
1-SW1           $15,282,896.055              (1)
1-SW1A          $ 1,628,501.456              (2)
1-SW1B          $ 1,628,501.456              (3)
1-SW2A          $ 1,887,123.945              (2)
1-SW2B          $ 1,887,123.945              (3)
1-SW3A          $ 2,200,962.416              (2)
1-SW3B          $ 2,200,962.416              (3)
1-SW4A          $ 2,238,394.397              (2)
1-SW4B          $ 2,238,394.397              (3)
1-SW5A          $ 2,072,386.347              (2)
1-SW5B          $ 2,072,386.347              (3)
1-SW6A          $ 1,867,418.198              (2)
1-SW6B          $ 1,867,418.198              (3)
</TABLE>


                                       1

<PAGE>

<TABLE>
<S>        <C>                          <C>
1-SW7A          $ 1,720,959.668              (2)
1-SW7B          $ 1,720,959.668              (3)
1-SW8A          $ 1,591,723.059              (2)
1-SW8B          $ 1,591,723.059              (3)
1-SW9A          $ 1,496,146.200              (2)
1-SW9B          $ 1,496,146.200              (3)
1-SW10A         $ 1,414,120.442              (2)
1-SW10B         $ 1,414,120.442              (3)
1-SW11A         $ 1,347,664.303              (2)
1-SW11B         $ 1,347,664.303              (3)
1-SW12A         $ 1,299,841.191              (2)
1-SW12B         $ 1,299,841.191              (3)
1-SW13A         $ 1,383,473.078              (2)
1-SW13B         $ 1,383,473.078              (3)
1-SW14A         $ 2,108,641.456              (2)
1-SW14B         $ 2,108,641.456              (3)
1-SW15A         $ 3,110,781.148              (2)
1-SW15B         $ 3,110,781.148              (3)
1-SW16A         $ 2,602,802.927              (2)
1-SW16B         $ 2,602,802.927              (3)
1-SW17A         $ 2,005,925.149              (2)
1-SW17B         $ 2,005,925.149              (3)
1-SW18A         $ 1,638,696.512              (2)
1-SW18B         $ 1,638,696.512              (3)
1-SW19A         $ 1,397,846.218               (2)
1-SW19B         $ 1,397,846.218              (3)
1-SW20A         $ 1,230,272.731              (2)
1-SW20B         $ 1,230,272.731              (3)
1-SW21A         $ 1,140,830.278              (2)
1-SW21B         $ 1,140,830.278              (3)
1-SW22A          $ 1,071,540.118              (2)
1-SW22B         $ 1,071,540.118              (3)
1-SW23A         $ 1,003,345.448              (2)
1-SW23B         $ 1,003,345.448              (3)
1-SW24A         $    939,517.135              (2)
1-SW24B         $    939,517.135               (3)
1-SW25A         $    969,015.879              (2)
1-SW25B         $    969,015.879              (3)
1-SW26A         $ 1,252,693.590              (2)
1-SW26B         $ 1,252,693.590              (3)
1-SW27A         $ 2,308,337.086              (2)
1-SW27B          $ 2,308,337.086              (3)
1-SW28A         $ 2,186,574.518              (2)
1-SW28B         $ 2,186,574.518              (3)
1-SW29A         $ 1,775,394.513              (2)
1-SW29B         $ 1,775,394.513              (3)
1-SW30A         $ 1,070,563.327              (2)
1-SW30B         $ 1,070,563.327              (3)
</TABLE>


                                       2

<PAGE>

<TABLE>
<S>        <C>                          <C>
1-SW31A         $     75,102.413              (2)
1-SW31B         $     75,102.413               (3)
1-SW32A         $    706,844.855              (2)
1-SW32B         $    706,844.855              (3)
1-SW33A         $    657,555.819              (2)
1-SW33B         $    657,555.819              (3)
1-SW34A         $    602,842.674              (2)
1-SW34B         $    602,842.674              (3)
1-SW35A         $    550,141.512              (2)
1-SW35B         $    550,141.512              (3)
1-SW36A         $    505,658.001              (2)
1-SW36B         $    505,658.001              (3)
1-SW37A         $    473,524.051              (2)
1-SW37B         $    473,524.051              (3)
1-SW38A         $    453,494.885              (2)
1-SW38B         $    453,494.885              (3)
1-SW39A         $    436,661.320              (2)
1-SW39B         $    436,661.320              (3)
1-SW40A         $    417,001.324              (2)
1-SW40B         $    417,001.324              (3)
1-SW41A         $    393,525.244              (2)
1-SW41B         $    393,525.244              (3)
1-SW42A         $    366,242.780              (2)
1-SW42B         $    366,242.780              (3)
1-SW43A         $    341,386.585              (2)
1-SW43B         $    341,386.585              (3)
1-SW44A         $    322,296.893              (2)
1-SW44B         $    322,296.893              (3)
1-SW45A         $    309,522.713              (2)
1-SW45B         $    309,522.713              (3)
1-SW46A         $    288,485.975              (2)
1-SW46B         $    288,485.975              (3)
1-SW47A         $    282,852.930              (2)
1-SW47B         $    282,852.930              (3)
1-SW48A         $    268,898.716              (2)
1-SW48B         $    268,898.716              (3)
1-SW49A         $    259,216.828              (2)
1-SW49B         $    259,216.828              (3)
1-SW50A         $    250,238.070              (2)
1-SW50B         $    250,238.070               (3)
1-SW51A         $    298,064.555              (2)
1-SW51B         $    298,064.555              (3)
1-SW52A         $    274,706.542              (2)
1-SW52B         $    274,706.542              (3)
1-SW53A         $    254,434.496              (2)
1-SW53B          $    254,434.496              (3)
1-SW54A         $ 7,400,131.739              (2)
1-SW54B         $ 7,400,131.739              (3)
</TABLE>


                                       3
<PAGE>

<TABLE>
<S>        <C>                          <C>
2-SW2           $20,961,128.195              (4)
2-SW1A          $ 2,233,557.544              (5)
2-SW1B          $ 2,233,557.544              (6)
2-SW2A          $ 2,588,269.055              (5)
2-SW2B          $ 2,588,269.055              (6)
2-SW3A          $ 3,018,711.584               (5)
2-SW3B          $ 3,018,711.584              (6)
2-SW4A          $ 3,070,051.103              (5)
2-SW4B          $ 3,070,051.103              (6)
2-SW5A          $ 2,842,364.153              (5)
2-SW5B          $ 2,842,364.153              (6)
2-SW6A           $ 2,561,241.802              (5)
2-SW6B          $ 2,561,241.802              (6)
2-SW7A          $ 2,360,367.832              (5)
2-SW7B          $ 2,360,367.832              (6)
2-SW8A          $ 2,183,114.441              (5)
2-SW8B          $ 2,183,114.441               (6)
2-SW9A          $ 2,052,026.800              (5)
2-SW9B          $ 2,052,026.800              (6)
2-SW10A         $ 1,939,525.058              (5)
2-SW10B         $ 1,939,525.058              (6)
2-SW11A         $ 1,848,377.697              (5)
2-SW11B          $ 1,848,377.697              (6)
2-SW12A         $ 1,782,786.309              (5)
2-SW12B         $ 1,782,786.309              (6)
2-SW13A         $ 1,897,490.922              (5)
2-SW13B         $ 1,897,490.922              (6)
2-SW14A         $ 2,892,089.544              (5)
2-SW14B         $ 2,892,089.544              (6)
2-SW15A         $ 4,266,565.852              (5)
2-SW15B         $ 4,266,565.852              (6)
2-SW16A         $ 3,569,852.573              (5)
2-SW16B         $ 3,569,852.573              (6)
2-SW17A         $ 2,751,209.851              (5)
2-SW17B         $ 2,751,209.851              (6)
2-SW18A         $ 2,247,540.488              (5)
2-SW18B         $ 2,247,540.488              (6)
2-SW19A         $ 1,917,204.282              (5)
2-SW19B         $ 1,917,204.282              (6)
2-SW20A         $ 1,687,370.269              (5)
2-SW20B         $ 1,687,370.269              (6)
2-SW21A         $ 1,564,696.222              (5)
2-SW21B         $ 1,564,696.222              (6)
2-SW22A         $ 1,469,661.882              (5)
2-SW22B         $ 1,469,661.882              (6)
2-SW23A         $ 1,376,130.052              (5)
2-SW23B         $ 1,376,130.052              (6)
2-SW24A         $ 1,288,586.865              (5)
</TABLE>


                                       4

<PAGE>

<TABLE>
<S>        <C>                          <C>
2-SW24B         $ 1,288,586.865              (6)
2-SW25A         $ 1,329,045.621              (5)
2-SW25B         $ 1,329,045.621              (6)
2-SW26A         $ 1,718,121.410              (5)
2-SW26B         $ 1,718,121.410              (6)
2-SW27A         $ 3,165,980.414              (5)
2-SW27B         $ 3,165,980.414              (6)
2-SW28A         $ 2,998,977.982              (5)
2-SW28B         $ 2,998,977.982              (6)
2-SW29A         $ 2,435,027.487              (5)
2-SW29B         $ 2,435,027.487              (6)
2-SW30A         $ 1,468,322.173              (5)
2-SW30B         $ 1,468,322.173              (6)
2-SW31A         $    103,006.087              (5)
2-SW31B         $    103,006.087              (6)
2-SW32A         $    969,467.145              (5)
2-SW32B         $    969,467.145              (6)
2-SW33A         $    901,865.181              (5)
2-SW33B         $    901,865.181              (6)
2-SW34A         $    826,823.826              (5)
2-SW34B         $    826,823.826               (6)
2-SW35A         $    754,541.988              (5)
2-SW35B         $    754,541.988              (6)
2-SW36A         $    693,530.999              (5)
2-SW36B         $    693,530.999              (6)
2-SW37A         $    649,457.949              (5)
2-SW37B          $    649,457.949              (6)
2-SW38A         $    621,987.115              (5)
2-SW38B         $    621,987.115              (6)
2-SW39A         $    598,899.180              (5)
2-SW39B         $    598,899.180              (6)
2-SW40A         $    571,934.676               (5)
2-SW40B         $    571,934.676              (6)
2-SW41A         $    539,736.256              (5)
2-SW41B         $    539,736.256              (6)
2-SW42A         $    502,317.220              (5)
2-SW42B         $    502,317.220              (6)
2-SW43A          $    468,225.915              (5)
2-SW43B         $    468,225.915              (6)
2-SW44A         $    442,043.607              (5)
2-SW44B         $    442,043.607              (6)
2-SW45A         $    424,523.287              (5)
2-SW45B         $    424,523.287              (6)
2-SW46A         $    395,670.525              (5)
2-SW46B         $    395,670.525              (6)
2-SW47A         $    387,944.570              (5)
2-SW47B         $    387,944.570              (6)
2-SW48A         $    368,805.784              (5)
</TABLE>


                                       5

<PAGE>

<TABLE>
<S>        <C>                          <C>
2-SW48B         $    368,805.784              (6)
2-SW49A         $    355,526.672              (5)
2-SW49B         $    355,526.672              (6)
2-SW50A         $    343,211.930              (5)
2-SW50B         $    343,211.930              (6)
2-SW51A         $    408,807.945              (5)
2-SW51B         $    408,807.945              (6)
2-SW52A         $    376,771.458              (5)
2-SW52B         $    376,771.458              (6)
2-SW53A         $    348,967.504              (5)
2-SW53B         $    348,967.504              (6)
2-SW54A         $10,149,588.761              (5)
2-SW54B         $10,149,588.761              (6)
SWR                            (7)           (7)
</TABLE>

(1)   The interest rate on the Class 1-SW1 Interest shall be a per annum rate
     equal to the Group One Net WAC.

(2)   For any Distribution Date, the interest rate on each SWAP REMIC Regular
     Interest beginning with the designation "1" and ending with the designation
     "A" shall be a per annum rate equal to 2 times the Group One Net WAC,
     subject to a maximum rate of 2 times the REMIC Swap Rate for such
     Distribution Date.

(3)   For any Distribution Date, the interest rate on each SWAP REMIC Regular
     Interest beginning with the designation "1" and ending with the designation
     "B" shall be a per annum rate equal to the greater of (x) the excess, if
     any, of (i) 2 times the Group One Net WAC over (ii) 2 times the REMIC Swap
      Rate for such Distribution Date and (y) 0.00%.

(4)   The interest rate on the Class 2-SW2 Interest shall be a per annum rate
     equal to the Group Two Net WAC.

(5)   For any Distribution Date, the interest rate on each SWAP REMIC Regular
     Interest beginning with the designation "2" and ending with the designation
     "A" shall be a per annum rate equal to 2 times the Group Two Net WAC,
     subject to a maximum rate of 2 times the REMIC Swap Rate for such
     Distribution Date.

(6)   For any Distribution Date, the interest rate on each SWAP REMIC Regular
     Interest beginning with the designation "2" and ending with the designation
     "B" shall be a per annum rate equal to the greater of (x) the excess, if
     any, of (i) 2 times the Group Two Net WAC over (ii) 2 times the REMIC Swap
     Rate for such Distribution Date and (y) 0.00%.

(7)   The Class SWR Interest shall have no principal amount and shall bear no
     interest.

THE LOWER TIER REMIC

     The following table sets forth the designations, initial principal
balances, interest rates, Corresponding Classes of Certificates and related
Mortgage Group for each interest in the Lower Tier REMIC:

<TABLE>
<CAPTION>
                                                           Class(es) of
                                                           Corresponding
                                                     Certificates or Related
Class     Initial Principal Balance    Interest Rate         Mortgage Group
-----     -------------------------    -------------    -----------------------
<S>       <C>                          <C>              <C>
LTA-1                (1)                     (8)                A-1, R
LTA-2A               (1)                     (8)                 A-2A
LTA-2B               (1)                     (8)                 A-2B
</TABLE>


                                       6

<PAGE>

<TABLE>
<S>       <C>                          <C>              <C>
LTA-2C               (1)                     (8)                 A-2C
LTA-2D               (1)                     (8)                 A-2D
LTM-1                (1)                     (8)                  M-1
LTM-2                (1)                     (8)                  M-2
LTM-3                (1)                     (8)                  M-3
LTM-4                 (1)                     (8)                  M-4
LTM-5                (1)                     (8)                  M-5
LTM-6                (1)                     (8)                  M-6
LTB-1                (1)                     (8)                  B-1
LTB-2                (1)                     (8)                  B-2
LTB-3                (1)                     (8)                  B-3
LTIX                 (2)                     (8)                  N/A
LTII1A               (3)                     (8)                Group One
LTII1B               (4)                     (9)               Group One
LTII2A               (5)                     (8)               Group Two
LTII2B               (6)                    (10)               Group Two
LTIIX                (7)                      (8)                  N/A
LT-IO               (11)                    (11)                  N/A
LTR                 (12)                    (12)                  N/A
</TABLE>

(1)   The initial principal balance of each of these Lower Tier REMIC Regular
     Interests shall equal 1/4 of the initial Certificate Principal Balance of
     its Corresponding Certificates.

(2)   The initial principal balance of the Class LTIX Interest shall equal the
     excess of (i) 50% of the aggregate Cut-off Date Principal Balance of the
     Mortgage Loans over (ii) the initial principal balance of the Lower Tier
     REMIC I Marker Interests.

(3)   The initial principal balance of the Class LTII1A Interest shall equal
     0.05% of the excess of (i) the aggregate Cut-off Date Principal Balance of
     the Group One Mortgage Loans over (ii) the aggregate of the initial
     Certificate Principal Balances of Certificate Group One.

(4)   The initial principal balance of the Class LTII1B Interest shall equal
     0.05% of the aggregate Cut-off Date Principal Balance of the Group One
     Mortgage Loans.

(5)   The initial principal balance of the Class LTII2A Interest shall equal
     0.05% of the excess of (i) the aggregate Cut-off Date Principal Balance of
     the Group Two Mortgage Loans over (ii) the aggregate of the initial
     Certificate Principal Balances of Certificate Group Two.

(6)   The initial principal balance of the Class LTII2B Interest shall equal
     0.05% of the aggregate Cut-off Date Principal Balance of the Group Two
     Mortgage Loans.

(7)   The initial principal balance of the Class LTIIX Interest shall equal the
     excess of (i) 50% of the aggregate Cut-off Date Principal Balance of the
     Mortgage Loans over (ii) the initial principal balance of the Lower Tier
     REMIC II Marker Interests.

(8)   For each Distribution Date, the interest rate for each of the Lower Tier
     REMIC Regular Interests (other than the Class LTII1B, the Class LTII2B and
     the Class LT-IO Interests) shall be a per annum rate (but not less than
     zero) equal to the product of (i) the weighted average of the interest
     rates on the SWAP REMIC Regular Interests for such Distribution Date and
     (ii) a fraction the numerator of which is 30 and the denominator of which
     is the actual number of days in the Accrual Period for the LIBOR
     Certificates, provided however, that for any Distribution Date on which the
     Class LT-IO Interest is entitled to a portion of interest accruals on a
     SWAP REMIC Regular Interest ending with a designation "A" as described in
     footnote 11 below, such weighted average shall be computed by first


                                       7

<PAGE>

     subjecting the rate on such SWAP REMIC Regular Interest to a cap equal to
     Swap LIBOR for such Distribution Date.

(9)   For each Distribution Date, the interest rate for the Class LTII1B Interest
     shall be a per annum rate equal to the product of (i) the weighted average
     of the interest rates on the SWAP REMIC Regular Interests beginning with
     the designation "1" for such Distribution Date and (ii) a fraction the
     numerator of which is 30 and the denominator of which is the actual number
     of days in the Accrual Period for the LIBOR Certificates, provided,
     however, that for any Distribution Date on which the Class LT-IO Interest
     is entitled to a portion of interest accruals on a SWAP REMIC Regular
     Interest ending with a designation "A" as described in footnote 11 below,
     such weighted average shall be computed by first subjecting the rate on
     such SWAP REMIC Regular Interest to a cap equal to Swap LIBOR for such
     Distribution Date.

(10) For each Distribution Date, the interest rate for the Class LTII2B Interest
     shall be a per annum rate equal to the product of (i) the weighted average
     of the interest rates on the SWAP REMIC Regular Interests beginning with
     the designation "2" for such Distribution Date and (ii) a fraction the
     numerator of which is 30 and the denominator of which is the actual number
     of days in the Accrual Period for the LIBOR Certificates, provided,
     however, that for any Distribution Date on which the Class LT-IO Interest
     is entitled to a portion of interest accruals on a SWAP REMIC Regular
     Interest ending with a designation "A" as described in footnote 11 below,
     such weighted average shall be computed by first subjecting the rate on
     such SWAP REMIC Regular Interest to a cap equal to Swap LIBOR for such
     Distribution Date.

(11) The Class LT-IO Interest is an interest-only class that does not have a
     principal balance. For only those Distribution Dates listed in the first
     column of the table below, the Class LT-IO Interest shall be entitled to
     interest accrued on the SWAP REMIC Regular Interest listed in the second
     column below at a per annum rate equal to the excess, if any, of (i) the
     interest rate for such SWAP REMIC Regular Interest for such Distribution
     Date over (ii) Swap LIBOR for such Distribution Date.

<TABLE>
<CAPTION>
Distribution Date    SWAP REMIC Regular Interest
-----------------    ---------------------------
<S>                  <C>
       7                    Class 1-SW1A
                           Class 2-SW1A
        7-8                  Class 1-SW2A
                           Class 2-SW2A
       7-9                  Class 1-SW3A
                           Class 2-SW3A
       7-10                 Class 1-SW4A
                           Class 2-SW4A
       7-11                  Class 1-SW5A
                           Class 2-SW5A
       7-12                 Class 1-SW6A
                           Class 2-SW6A
       7-13                 Class 1-SW7A
                           Class 2-SW7A
       7-14                 Class 1-SW8A
                           Class 2-SW8A
       7-15                 Class 1-SW9A
                           Class 2-SW9A
       7-16                 Class 1-SW10A
                           Class 2-SW10A
       7-17                 Class 1-SW11A
                            Class 2-SW11A
       7-18                 Class 1-SW12A
                           Class 2-SW12A
       7-19                 Class 1-SW13A
                           Class 2-SW13A
       7-20                 Class 1-SW14A
</TABLE>


                                        8

<PAGE>

<TABLE>
<S>                  <C>
                           Class 2-SW14A
       7-21                 Class 1-SW15A
                           Class 2-SW15A
       7-22                 Class 1-SW16A
                            Class 2-SW16A
       7-23                 Class 1-SW17A
                           Class 2-SW17A
       7-24                 Class 1-SW18A
                           Class 2-SW18A
       7-25                 Class 1-SW19A
                           Class 2-SW19A
       7-26                 Class 1-SW20A
                           Class 2-SW20A
       7-27                 Class 1-SW21A
                           Class 2-SW21A
       7-28                 Class 1-SW22A
                           Class 2-SW22A
       7-29                 Class 1-SW23A
                           Class 2-SW23A
       7-30                 Class 1-SW24A
                           Class 2-SW24A
       7-31                 Class 1-SW25A
                           Class 2-SW25A
       7-32                 Class 1-SW26A
                           Class 2-SW26A
       7-33                 Class 1-SW27A
                           Class 2-SW27A
       7-34                 Class 1-SW28A
                           Class 2-SW28A
       7-35                  Class 1-SW29A
                           Class 2-SW29A
       7-36                 Class 1-SW30A
                           Class 2-SW30A
       7-37                 Class 1-SW31A
                           Class 2-SW31A
       7-38                 Class 1-SW32A
                           Class 2-SW32A
       7-39                 Class 1-SW33A
                           Class 2-SW33A
       7-40                 Class 1-SW34A
                           Class 2-SW34A
       7-41                 Class 1-SW35A
                           Class 2-SW35A
       7-42                 Class 1-SW36A
                           Class 2-SW36A
       7-43                 Class 1-SW37A
                           Class 2-SW37A
       7-44                 Class 1-SW38A
                            Class 2-SW38A
       7-45                 Class 1-SW39A
                           Class 2-SW39A
       7-46                 Class 1-SW40A
                           Class 2-SW40A
       7-47                 Class 1-SW41A
                            Class 2-SW41A
       7-48                 Class 1-SW42A
</TABLE>


                                       9

<PAGE>

<TABLE>
<S>                  <C>
                           Class 2-SW42A
       7-49                 Class 1-SW43A
                            Class 2-SW43A
       7-50                 Class 1-SW44A
                           Class 2-SW44A
       7-51                 Class 1-SW45A
                           Class 2-SW45A
       7-52                 Class 1-SW46A
                            Class 2-SW46A
       7-53                 Class 1-SW47A
                           Class 2-SW47A
       7-54                 Class 1-SW48A
                           Class 2-SW48A
       7-55                 Class 1-SW49A
                           Class 2-SW49A
       7-56                 Class 1-SW50A
                           Class 2-SW50A
       7-57                 Class 1-SW51A
                           Class 2-SW51A
       7-58                 Class 1-SW52A
                           Class 2-SW52A
        7-59                 Class 1-SW53A
                           Class 2-SW53A
       7-60                 Class 1-SW54A
                           Class 2-SW54A
</TABLE>

(12) The Class LTR Interest shall have no principal amount and shall bear no
     interest.

UPPER TIER REMIC

The following table sets forth the designation, the initial principal balances,
the interest rates and Classes of Related Certificates for each of the interests
in the Upper Tier REMIC.

<TABLE>
<CAPTION>
                                    Initial
                                  Principal           Class of Related
Class                               Balance     Rate      Certificates
-----                              ---------    ----    ----------------
<S>                                 <C>          <C>     <C>
UTA-1                                 (1)        (2)          A-1
UTA-2A                                (1)        (2)          A-2A
UTA-2B                                (1)        (2)          A-2B
UTA-2C                                (1)        (2)          A-2C
UTA-2D                                (1)        (2)          A-2D
UTM-1                                 (1)        (2)          M-1
UTM-2                                 (1)        (2)          M-2
UTM-3                                 (1)         (2)          M-3
UTM-4                                 (1)        (2)          M-4
UTM-5                                 (1)        (2)          M-5
UTM-6                                 (1)        (2)          M-6
UTB-1                                 (1)         (2)          B-1
UTB-2                                 (1)        (2)          B-2
UTB-3                                 (1)        (2)          B-3
Uncertificated Class C Interest       (3)        (3)          N/A
UT-IO                                 (4)        (4)          N/A
Residual Interest                     (1)        (2)           R
</TABLE>


                                       10

<PAGE>

(1)   The initial principal balance of each of these REMIC Regular Interests
     shall equal the initial principal balance of its Class of Related
     Certificates.

(2)   The interest rates on each of these REMIC Regular Interests shall be an
     annual rate equal to the Pass-Through Rate for the Class of Related
     Certificates, provided that in lieu of the applicable Available Funds Caps
     set forth in the definition of an applicable Pass-Through Rate, the
     applicable Upper Tier REMIC Net WAC Cap shall be used.

(3)   The Uncertificated Class C Interest shall have an initial principal balance
     equal to the initial Overcollateralization Amount. The Uncertificated Class
     C Interest shall accrue interest on a notional balance set forth in the
     definition of Class C Current Interest at a rate equal to the Class C
     Distributable Interest Rate. The Uncertificated Class C Interest shall be
     represented by the Class C Certificates.

(4)   The Class UT-IO Interest shall have no principal amount and will not have
     an interest rate, but will be entitled to 100% of the interest accrued with
     respect to the Class LT-IO Interest. The Class UT-IO Interest shall be
     represented by the Class C Certificates.

THE CERTIFICATES

The following table sets forth the Class designation, interest rate and initial
Class principal amount for each Class of Certificates comprising interests in
the Trust Fund.

<TABLE>
<CAPTION>
          Initial Class
Class    Principal Amount    Interest Rate
-----    ----------------    -------------
<S>      <C>                 <C>
A-1             (1)              (2)
A-2A            (1)              (2)
A-2B            (1)              (2)
A-2C            (1)              (2)
A-2D            (1)              (2)
M-1             (1)              (2)
M-2             (1)              (2)
M-3             (1)              (2)
M-4             (1)               (2)
M-5             (1)              (2)
M-6             (1)              (2)
B-1             (1)              (2)
B-2             (1)              (2)
B-3             (1)              (2)
C               (3)              (3)
P               (4)              (4)
R                (1)              (2)(5)
</TABLE>

(1)   Each of these Classes of Certificates shall have initial principal balances
     as set forth in Section 5.01 hereof.

(2)   Each of these Classes of Certificates shall bear interest at a per annum
     rate equal to the Pass-Through Rate for such Certificates set forth in the
     definitions herein.

(3)   For federal income tax purposes, the Class C Certificate shall represent
     (i) the right to receive all distributions with respect to the REMIC
     Regular Interests represented by the Uncertificated Class C Interest and
     the


                                       11
<PAGE>

     Class UT-IO Interest and (ii) certain rights and obligations with respect
     to notional principal contracts as described in Section 2.07.

(4)   The Class P Certificates shall be entitled to the amounts distributable
     pursuant to Section 4.04(b) hereof and shall not represent a REMIC regular
     interest.

(5)   The Class R Interest represents ownership of the Class SWR Interest, the
     Class LTR Interest and the Residual Interest.

     In consideration of the mutual agreements herein contained, the Depositor,
the Servicer and the Trustee hereby agree as follows:

                                    ARTICLE I
                                    DEFINITIONS

     Whenever used in this Agreement, the following words and phrases, unless
the context otherwise requires, shall have the following meanings:

     Accepted Servicing Practices: The Servicer's normal servicing practices,
which will conform to the mortgage servicing practices of prudent mortgage
lending institutions that service for their own account mortgage loans of the
same type as the Mortgage Loans in the jurisdictions in which the related
Mortgaged Properties are located.

     Accountant's Attestation: As defined in Section 3.18(b) hereof.

     Accrual Period: With respect to each Class of the LIBOR Certificates, their
Corresponding REMIC Regular Interests and the Lower Tier REMIC Interests and any
Distribution Date, the period commencing on the immediately preceding
Distribution Date (or, in the case of the first Distribution Date, the Closing
Date) and ending on the day immediately preceding such Distribution Date, and
with respect to the SWAP REMIC Regular Interests and any Distribution Date, the
calendar month immediately preceding the month in which such Distribution Date
occurs. All calculations of interest on each Class of the LIBOR Certificates,
their Corresponding REMIC Regular Interests and the Lower Tier REMIC Interests
will be made on the basis of the actual number of days elapsed in the related
Accrual Period and a 360 day year, and all calculations of interest on the SWAP
REMIC Regular Interests will be made on the basis of a 360-day year consisting
of twelve 30-day months.

     Additional Form 10-D Disclosure: As defined in Section 3.20 hereof.

     Adjustable Rate Mortgage Loan: A Mortgage Loan identified in the Mortgage
Loan Schedule as having a Mortgage Rate that is adjustable.

     Adjustment Date: As to each Adjustable Rate Mortgage Loan, each date on
which the related Mortgage Rate is subject to adjustment, as provided in the
related Mortgage Note.

     Advance: The aggregate of the advances required to be made by the Servicer
with respect to any Distribution Date pursuant to Section 4.01, the amount of
any such advances being equal to the sum of the aggregate amount of all payments
of principal and interest (or, with respect to the interest-only Mortgage Loans,
payments of scheduled interest) (net of the Servicing Fee) on the related
Mortgage Loans that were due during the applicable Due Period and not received
as of the close of business on the related Determination Date, except as
provided in Section 4.01 hereof, less the aggregate amount of any such
Delinquent payments that the Servicer has determined would constitute a
Non-Recoverable Advance


                                       12

<PAGE>

were an advance to be made with respect thereto; provided, however, that with
respect to (i) any Mortgage Loan that is 150 days delinquent or more (whether or
not the Mortgage Loan has been converted to an REO Property), (ii) shortfalls
due to bankruptcy proceedings or the application of the Relief Act or similar
law and (iii) the principal portion of any amount paid on a Balloon Loan, there
will be no obligation to make advances and, provided further, however, that with
respect to any Mortgage Loan that has been converted to an REO Property which is
less than 150 days delinquent, the obligation to make Advances shall only be to
payments of interest (subject to the exceptions described above and net of the
related Servicing Fees), to be calculated after taking into account any rental
income.

     Advance Facility: A financing or other facility as described in Section
10.14(b).

     Advance Facility Notice: As defined in Section 10.14(b).

     Advance Financing Person: As defined in Section 10.14(a).

     Advance Reimbursement Amounts: As defined in Section 10.14(a).

     Affiliate: With respect to any specified Person, any other Person
controlling, controlled by or under common control with such Person. For the
purposes of this definition, "control" means the power to direct the management
and policies of a Person, directly or indirectly, whether through ownership of
voting securities, by contract or otherwise; and the terms "controlling" and
"controlled" have meanings correlative to the foregoing.

     Aggregate Certificate Principal Balance: For any date of determination, the
sum of the Class A-1 Certificate Principal Balance, the Class A-2A Certificate
Principal Balance, the Class A-2B Certificate Principal Balance, the Class A-2C
Certificate Principal Balance, the Class A-2D Certificate Principal Balance, the
Class R Certificate Principal Balance, the Class M-1 Certificate Principal
Balance, the Class M-2 Certificate Principal Balance, the Class M-3 Certificate
Principal Balance, the Class M-4 Certificate Principal Balance, the Class M-5
Certificate Principal Balance, the Class M-6 Certificate Principal Balance, the
Class B-1 Certificate Principal Balance, the Class B-2 Certificate Principal
Balance, and the Class B-3 Certificate Principal Balance, in each case as of
such date of determination.

     Agreement: This Pooling and Servicing Agreement and any and all amendments
or supplements hereto made in accordance with the terms herein.

     Applied Realized Loss Amount: With respect to any Distribution Date, the
amount, if any, by which, the sum of (i) the Aggregate Certificate Principal
Balance and (ii) the Class C Certificate Principal Balance after distributions
of principal on such Distribution Date exceeds the aggregate Stated Principal
Balance of the Mortgage Loans as of such Distribution Date.

     Appraised Value: With respect to a Mortgage Loan the proceeds of which were
used to purchase the related Mortgaged Property, the "Appraised Value" of a
Mortgaged Property is the lesser of (1) the appraised value based on an
appraisal made for the Sponsor by an independent fee appraiser at the time of
the origination of the related Mortgage Loan, and (2) the sales price of such
Mortgaged Property at such time of origination. With respect to a Mortgage Loan
the proceeds of which were used to refinance an existing mortgage loan, the
"Appraised Value" is the appraised value of the Mortgaged Property based upon
the appraisal obtained at the time of refinancing.

     Assessment of Compliance: As defined in Section 3.18(a) hereof.


                                       13

<PAGE>

     Assignment of Mortgage: An assignment of the Mortgage, notice of transfer
or equivalent instrument, in recordable form, sufficient under the laws of the
jurisdiction where the related Mortgaged Property is located to reflect of
record the sale and assignment of the Mortgage Loan to the Trustee, which
assignment, notice of transfer or equivalent instrument may, if permitted by
law, be in the form of one or more blanket assignments covering Mortgages
secured by Mortgaged Properties located in the same county.

     Auction Termination: The termination of the Trust Fund hereunder pursuant
to Section 9.01(a)(i) hereof.

     Auction Termination Amount: The purchase price received by the Trustee in
connection with any purchase of all of the Mortgage Loans pursuant to Section
9.01(a)(i).

     Auction Termination Date: The first Distribution Date on which the
aggregate Stated Principal Balance of the Mortgage Loans (or if such Mortgage
Loan is an REO Property, the fair market value of such REO Property) is equal to
or less than 10% of the aggregate Stated Principal Balance of the Mortgage Loans
as of the Cut-off Date.

     Auction Termination Price: In the case of an Auction Termination, as of the
initial Distribution Date on or after the Auction Termination Date, an amount
equal to the sum of (a) the aggregate Stated Principal Balance of each Mortgage
Loan (other than any Mortgage Loan that has become an REO Property), plus
accrued interest thereon at the applicable Mortgage Rate through the Due Date
preceding distribution of the proceeds, (b) the fair market value of any REO
Property, plus accrued interest thereon at the applicable Mortgage Rate, (c) any
unreimbursed fees, indemnification amounts, out-of-pocket costs and expenses
owed to the Trustee or the Servicer (including any costs and expenses incurred
in connection with the Auction Termination) and any unreimbursed Servicing Fees,
Advances and Servicing Advances, (d) all interest accrued on, as well as amounts
necessary to retire, the principal balance of any NIM Notes, (e) any costs and
damages incurred by the Issuing Entity (or the Trustee on behalf of the Issuing
Entity) in connection with any violation of any anti-predatory or anti-abusive
lending laws and (f) any Swap Termination Payment, other than a Defaulted Swap
Termination Payment, owed to the Swap Counterparty; such Swap Termination
Payment shall include any payment resulting from the termination of the Swap
Agreement after the Auction Termination Date but prior to the final distribution
to the Certificates.

     Authenticating Agent: As defined in Section 5.10.

     Available Funds Cap: Any of the Class A-1 Available Funds Cap, the Class
A-2 Available Funds Cap, or the Subordinate Certificate Available Funds Cap.

     Balloon Loan: A Mortgage Loan having an original term to stated maturity of
approximately 15 or 30 years which provides for level monthly payments of
principal and interest based on a 30-, 40-, 45- or 50-year amortization
schedule, with a balloon payment of the remaining outstanding principal balance
due on such Mortgage Loan at its stated maturity.

     Book-Entry Certificates: Any of the Certificates that shall be registered
in the name of the Depository or its nominee, the ownership of which is
reflected on the books of the Depository or on the books of a Person maintaining
an account with the Depository (directly, as a "Depository Participant", or
indirectly, as an indirect participant in accordance with the rules of the
Depository and as described in Section 5.06). As of the Closing Date, each of
the Class A, Class M and Class B Certificates constitute a Class of Book-Entry
Certificates.


                                       14

<PAGE>

     Business Day: Any day other than (1) a Saturday or a Sunday, or (2) a day
on which banking institutions in the State of Oregon or Minnesota or in the City
of New York, New York are authorized or obligated by law or executive order to
be closed.

     Cap Contract Counterparty: The Bank of New York, and any successor thereto.

     Cap Posted Collateral Account: The segregated Eligible Account that may be
created and maintained by the Trustee pursuant to Section 4.04(j)(iv) in the
name of the Trustee for the benefit of the Issuing Entity and designated "U.S.
Bank National Association, as trustee, in trust for registered holders of
Specialty Underwriting and Residential Finance Trust, Mortgage Loan Asset-Backed
Certificates, Series 2007-AB1." Funds in the Posted Collateral Account shall be
held in trust for the Issuing Entity for the uses and purposes set forth in this
Agreement.

     Certificate: Any one of the certificates of any Class executed by the
Trustee and authenticated by the Authenticating Agent in substantially the forms
attached hereto as Exhibit A.

     Certificate Account: The separate Eligible Account created and maintained
by the Trustee pursuant to Section 3.05(f) in the name of the Trustee for the
benefit of the Certificateholders and designated "U.S. Bank National
Association, as trustee, in trust for registered holders of Specialty
Underwriting and Residential Finance Trust, Mortgage Loan Asset-Backed
Certificates, Series 2007-AB1." Funds in the Certificate Account shall be held
in trust for the Certificateholders for the uses and purposes set forth in this
Agreement.

     Certificate Group: Either of Certificate Group One or Certificate Group
Two.

     Certificate Group One: The Class A-1 and Class R Certificates. For purposes
of Section 2.07 hereof, Certificate Group One shall be related to Group One.

     Certificate Group Two: The Class A-2 Certificates. For purposes of Section
2.07 hereof, Certificate Group Two shall be related to Group Two.

     Certificate Owner: With respect to a Book-Entry Certificate, the Person
that is the beneficial owner of such Book-Entry Certificate.

     Certificate Principal Balance: As to any Certificate and as of any
Distribution Date, the Initial Certificate Principal Balance of such Certificate
less the sum of (1) all amounts distributed with respect to such Certificate in
reduction of the Certificate Principal Balance thereof on previous Distribution
Dates pursuant to Section 4.04, and (2) any Applied Realized Loss Amounts
allocated to such Certificate on previous Distribution Dates pursuant to Section
4.04(h). On each Distribution Date, after all distributions of principal on such
Distribution Date, a portion of the Class C Interest Carry Forward Amount in an
amount equal to the excess of the Overcollateralization Amount on such
Distribution Date over the Overcollateralization Amount as of the preceding
Distribution Date (or, in the case of the first Distribution Date, the initial
Overcollateralization Amount (based on the Stated Principal Balance of the
Mortgage Loans as of the Cut-off Date)) will be added to the aggregate
Certificate Principal Balance of the Class C Certificates (on a pro rata basis).
Notwithstanding the immediately preceding sentence, however, to the extent any
excess referred to in the immediately preceding sentence is attributable to
distributions of proceeds of the Swap Agreement, such sentence shall be applied
by substituting the "Class C Unpaid Realized Loss Amount" for the "Class C
Interest Carry Forward Amount". Notwithstanding the foregoing on any
Distribution Date relating to a Due Period in which a Subsequent Recovery has
been received by the Servicer, the Certificate Principal Balance of any Class of
Certificates then outstanding for which any Applied Realized Loss Amount has
been allocated will be increased, in


                                       15

<PAGE>

order of seniority, by an amount equal to the lesser of (i) the Unpaid Realized
Loss Amount for such Class of Certificates and (ii) the total of any Subsequent
Recovery distributed on such date to the Certificateholders (reduced by the
amount of the increase in the Certificate Principal Balance of any more senior
Class of Certificates pursuant to this sentence on such Distribution Date).

     Certificate Register: The register maintained pursuant to Section 5.02
hereof.

     Certificateholder or Holder: The Person in whose name a Certificate is
registered in the Certificate Register (initially, Cede & Co., as nominee for
the Depository) in the case of any Class of Regular Certificates or the Class R
Certificate, except that solely for the purpose of giving any consent pursuant
to this Agreement, any Certificate registered in the name of the Depositor or
any Affiliate of the Depositor shall be deemed not to be Outstanding and the
Percentage Interest evidenced thereby shall not be taken into account in
determining whether the requisite amount of Percentage Interests necessary to
effect such consent has been obtained; provided, however, that if any such
Person (including the Depositor) owns 100% of the Percentage Interests evidenced
by a Class of Certificates, such Certificates shall be deemed to be Outstanding
for purposes of any provision hereof that requires the consent of the Holders of
Certificates of a particular Class as a condition to the taking of any action
hereunder. The Trustee is entitled to rely conclusively on a certification of
the Depositor or any Affiliate of the Depositor in determining which
Certificates are registered in the name of an Affiliate of the Depositor.

     Class: All Certificates bearing the same Class designation as set forth in
Section 5.01 hereof.

     Class A Certificate Principal Balance: As of any date of determination, the
sum of the Class A-1 Certificate Principal Balance, the Class A-2A Certificate
Principal Balance, the Class A-2B Certificate Principal Balance, the Class A-2C
Certificate Principal Balance and the Class A-2D Certificate Principal Balance.

     Class A Certificates: Any of the Class A-1, Class A-2A, Class A-2B, Class
A-2C and Class A-2D Certificates.

     Class A Principal Distribution Amount: With respect to any Distribution
Date (1) prior to the related Stepdown Date or any Distribution Date on which a
Stepdown Trigger Event exists, 100% of the Principal Distribution Amount for
such Distribution Date and (2) on or after the Stepdown Date where a Stepdown
Trigger Event does not exist, the excess of (A) the Certificate Principal
Balance of the Class A and Class R Certificates immediately prior to such
Distribution Date over (B) the lesser of (1) 73.40% of the aggregate Stated
Principal Balance of the Mortgage Loans and (2) the excess of the aggregate
Stated Principal Balance of the Mortgage Loans over the Minimum Required
Overcollateralization Amount; provided, however, that in no event will the Class
A Principal Distribution Amount with respect to any Distribution Date exceed the
aggregate Certificate Principal Balance of the Class A and Class R Certificates.

     Class A-1 Available Funds Cap: With respect to a Distribution Date, the per
annum rate equal to the product of (i) 12, (ii) the quotient of (x) the total
scheduled interest on the Mortgage Loans in Group One based on the Net Mortgage
Rates in effect on the related Due Date, less the pro rata portion (calculated
based on the ratio of the Stated Principal Balance of the Mortgage Loans in
Group One to the Stated Principal Balance of the total pool of Mortgage Loans)
allocable to the Mortgage Loans in Group One of any Net Swap Payments or Swap
Termination Payments (other than Defaulted Swap Termination Payments) owed to
the Swap Counterparty for such Distribution Date, and (y) the aggregate Stated
Principal Balance of the Mortgage Loans in Group One as of the first day of the
related Accrual Period (or, in the case of the first Distribution Date, as of
the Cut-off Date) and (iii) a fraction, the numerator of which is 30, and the
denominator of which is the actual number of days in the related Accrual Period.


                                       16

<PAGE>

The Class A-1 Available Funds Cap shall be related to the Class A-1 Certificates
and the Class R Certificate.

     Class A-1 Certificate: Any Certificate designated as a "Class A-1
Certificate" on the face thereof, executed by the Trustee and authenticated by
the Authenticating Agent in substantially the form set forth in Exhibit A,
representing the right to distributions as set forth herein.

     Class A-1 Certificate Principal Balance: As of any date of determination,
the aggregate Certificate Principal Balance of the Class A-1 Certificates.

     Class A-1 Corridor Contract: The confirmation and agreement (together with
the schedule thereto) and any related credit support annex (attached as Exhibit
O-4 hereto), between the Trustee, on behalf of the Issuing Entity, and the Cap
Contract Counterparty (attached as Exhibit O-1 hereto), with respect to the
Class A-1 Certificates.

     Class A-1 Corridor Contract Notional Balance: With respect to any
Distribution Date, the Class A-1 Corridor Contract Notional Balance set forth
for such Distribution Date in the Class A-1 Corridor Contract (attached as
Exhibit O-1 hereto).

     Class A-1 Corridor Contract Termination Date: The Distribution Date after
the Distribution Date in September 2007.

     Class A-1 Current Interest: As of any Distribution Date, the interest
accrued during the related Accrual Period at the Class A-1 Pass-Through Rate on
the Class A-1 Certificate Principal Balance as of such Distribution Date plus
the portion of any previous distributions on such Class in respect of Class A-1
Current Interest or a Class A-1 Interest Carry Forward Amount that is recovered
as a voidable preference by a trustee in bankruptcy, less any Non-Supported
Interest Shortfall allocated on such Distribution Date to the Class A-1
Certificates.

     Class A-1 Interest Carry Forward Amount: As of any Distribution Date, the
sum of (1) the excess of (A) the Class A-1 Current Interest with respect to
prior Distribution Dates over (B) the amount actually distributed to the Class
A-1 Certificates with respect to Current Interest or Interest Carry Forward
Amounts on such prior Distribution Dates and (2) interest on such excess (to the
extent permitted by applicable law) at the Class A-1 Pass-Through Rate for the
related Accrual Period.

     Class A-1 Margin: As of any Distribution Date up to and including the
Auction Termination Date, 0.2400% per annum and, as of any Distribution Date
after the Auction Termination Date, 0.4800% per annum.

     Class A-1 Maximum Rate Cap: With respect to a Distribution Date, the per
annum rate equal to the product of (i) 12, (ii) the quotient of (x) the total
scheduled interest that would have been due on the Group One Mortgage Loans had
the Adjustable Rate Mortgage Loans provided for interest at their maximum
lifetime Net Mortgage Rates and the Fixed Rate Mortgage Loans provided for
interest at their Net Mortgage Rates less the pro rata portion (calculated based
on the ratio of the Stated Principal Balance of the Group One Mortgage Loans to
the Stated Principal Balance of the total pool of Mortgage Loans) allocable to
the Group One Mortgage Loans of any Net Swap Payments or Swap Termination
Payments owed to the Swap Counterparty for such Distribution Date (other than
Defaulted Swap Termination Payments), and (y) the aggregate Stated Principal
Balance of the Group One Mortgage Loans as of the first day of the related
Accrual Period (or, in the case of the first Distribution Date, as of the
Cut-off Date) and (iii) a fraction, the numerator of which is 30 and the
denominator of which is the


                                       17

<PAGE>


actual number of days in the related Accrual Period. The Class A-1 Maximum Rate
Cap shall be related to the Class A-1 Certificates and Class R Certificate.

     Class A-1 Pass-Through Rate: For the first Distribution Date, 5.56% per
annum. As of any Distribution Date thereafter, the least of (1) One-Month LIBOR
plus the Class A-1 Margin, (2) the Class A-1 Available Funds Cap, and (3) the
Class A-1 Maximum Rate Cap for such Distribution Date.

     Class A-1 Upper Collar: With respect to each Distribution Date with respect
to which payments are received on the Class A-1 Corridor Contract, a rate equal
to the lesser of One-Month LIBOR and 10.760% per annum.

     Class A-2 Available Funds Cap: With respect to a Distribution Date, the per
annum rate equal to the product of (i) 12, (ii) the quotient of (x) the total
scheduled interest on the Mortgage Loans in Group Two based on the Net Mortgage
Rates in effect on the related Due Date, less the pro rata portion (calculated
based on the ratio of the Stated Principal Balance of the Mortgage Loans in
Group Two to the Stated Principal Balance of the total pool of Mortgage Loans)
allocable to the Mortgage Loans in Group Two of any Net Swap Payments or Swap
Termination Payments (other than Defaulted Swap Termination Payments) owed to
the Swap Counterparty for such Distribution Date, and (y) the aggregate Stated
Principal Balance of the Mortgage Loans in Group Two as of the first day of the
related Accrual Period (or, in the case of the first Distribution Date, as of
the Cut-off Date) and, (iii) a fraction, the numerator of which is 30, and the
denominator of which is the actual number of days in the related Accrual Period.
The Class A-2 Available Funds Cap shall be related to the Class A-2
Certificates.

     Class A-2 Certificates: The Class A-2A, Class A-2B, Class A-2C and Class
A-2D Certificates.

     Class A-2 Corridor Contract: The confirmation and agreement (together with
the schedule thereto) and any related credit support annex (attached as Exhibit
O-4 hereto), between the Trustee, on behalf of the Issuing Entity, and the Cap
Contract Counterparty (attached as Exhibit O-2 hereto), with respect to the
Class A-2 Certificates.

     Class A-2 Corridor Contract Notional Balance: With respect to any
Distribution Date, the Class A-2 Corridor Contract Notional Balance set forth
for such Distribution Date in the Class A-2 Corridor Contract (attached as
Exhibit O-2 hereto).

     Class A-2 Corridor Contract Termination Date: The Distribution Date after
the Distribution Date in September 2007.

     Class A-2 Maximum Rate Cap: With respect to a Distribution Date, the per
annum rate equal to the product of (i) 12 and (ii) the quotient of (x) the total
scheduled interest that would have been due on the Group Two Mortgage Loans had
the Adjustable Rate Mortgage Loans provided for interest at their maximum
lifetime Net Mortgage Rates and the Fixed Rate Mortgage Loans provided for
interest at their Net Mortgage Rates less the pro rata portion (calculated based
on the ratio of the Stated Principal Balance of the Group Two Mortgage Loans to
the total pool of Stated Principal Balance of the Mortgage Loans) allocable to
the Group Two Mortgage Loans of any Net Swap Payments or Swap Termination
Payments owed to the Swap Counterparty for such Distribution Date (other than
Defaulted Swap Termination Payments), and (y) the aggregate Stated Principal
Balance of the Group Two Mortgage Loans as of the first day of the related
Accrual Period (or, in the case of the first Distribution Date, as of the
Cut-off Date) and (iii) a fraction, the numerator of which is 30 and the
denominator of which is the actual number of days in the related Accrual Period.
The Class A-2 Maximum Rate Cap shall be related to the Class A-2 Certificates.


                                        18

<PAGE>

     Class A-2 Upper Collar: With respect to each Distribution Date with respect
to which payments are received on the Class A-2 Corridor Contract, a rate equal
to the lesser of One-Month LIBOR and 10.000% per annum.

     Class A-2A Certificate: Any Certificate designated as a "Class A-2A
Certificate" on the face thereof, executed by the Trustee and authenticated by
the Authenticating Agent in substantially the form set forth in Exhibit A,
representing the right to distributions as set forth herein.

     Class A-2A Certificate Principal Balance: As of any date of determination,
the aggregate Certificate Principal Balance of the Class A-2A Certificates.

     Class A-2A Current Interest: As of any Distribution Date, the interest
accrued during the related Accrual Period at the Class A-2A Pass-Through Rate on
the Class A-2A Certificate Principal Balance as of such Distribution Date plus
the portion of any previous distributions on such Class in respect of Class A-2A
Current Interest or a Class A-2A Interest Carry Forward Amount that is recovered
as a voidable preference by a trustee in bankruptcy, less any Non-Supported
Interest Shortfall allocated on such Distribution Date to the Class A-2A
Certificates.

     Class A-2A Interest Carry Forward Amount: As of any Distribution Date, the
sum of (1) the excess of (A) the Class A-2A Current Interest with respect to
prior Distribution Dates over (B) the amount actually distributed to the Class
A-2A Certificates with respect to Current Interest or Interest Carry Forward
Amounts on such prior Distribution Dates and (2) interest on such excess (to the
extent permitted by applicable law) at the Class A-2A Pass-Through Rate for the
related Accrual Period.

     Class A-2A Margin: As of any Distribution Date up to and including the
Auction Termination Date, 0.1200% per annum and, as of any Distribution Date
after the Auction Termination Date, 0.2400% per annum.

     Class A-2A Pass-Through Rate: For the first Distribution Date, 5.44% per
annum. As of any Distribution Date thereafter, the least of (1) One-Month LIBOR
plus the Class A-2A Margin, (2) the Class A-2 Available Funds Cap and (3) the
Class A-2 Maximum Rate Cap for such Distribution Date.


     Class A-2B Certificate: Any Certificate designated as a "Class A-2B
Certificate" on the face thereof, executed by the Trustee and authenticated by
the Authenticating Agent in substantially the form set forth in Exhibit A,
representing the right to distributions as set forth herein.

     Class A-2B Certificate Principal Balance: As of any date of determination,
the aggregate Certificate Principal Balance of the Class A-2B Certificates.

     Class A-2B Current Interest: As of any Distribution Date, the interest
accrued during the related Accrual Period at the Class A-2B Pass-Through Rate on
the Class A-2B Certificate Principal Balance as of such Distribution Date plus
the portion of any previous distributions on such Class in respect of Class A-2B
Current Interest or a Class A-2B Interest Carry Forward Amount that is recovered
as a voidable preference by a trustee in bankruptcy, less any Non-Supported
Interest Shortfall allocated on such Distribution Date to the Class A-2B
Certificates.

     Class A-2B Interest Carry Forward Amount: As of any Distribution Date, the
sum of (1) the excess of (A) the Class A-2B Current Interest with respect to
prior Distribution Dates over (B) the amount actually distributed to the Class
A-2B Certificates with respect to Current Interest or Interest Carry Forward
Amounts on such prior Distribution Dates and (2) interest on such excess (to the
extent permitted by applicable law) at the Class A-2B Pass-Through Rate for the
related Accrual Period.


                                       19

<PAGE>


     Class A-2B Margin: As of any Distribution Date up to and including the
Auction Termination Date, 0.1900% per annum and, as of any Distribution Date
after the Auction Termination Date, 0.3800% per annum.

     Class A-2B Pass-Through Rate: For the first Distribution Date, 5.51% per
annum. As of any Distribution Date thereafter, the least of (1) One-Month LIBOR
plus the Class A-2B Margin, (2) the Class A-2 Available Funds Cap and (3) the
Class A-2 Maximum Rate Cap for such Distribution Date.

     Class A-2C Certificate: Any Certificate designated as a "Class A-2C
Certificate" on the face thereof, executed by the Trustee and authenticated by
the Authenticating Agent in substantially the form set forth in Exhibit A,
representing the right to distributions as set forth herein.

     Class A-2C Certificate Principal Balance: As of any date of determination,
the aggregate Certificate Principal Balance of the Class A-2C Certificates.

     Class A-2C Current Interest: As of any Distribution Date, the interest
accrued during the related Accrual Period at the Class A-2C Pass-Through Rate on
the Class A-2C Certificate Principal Balance as of such Distribution Date plus
the portion of any previous distributions on such Class in respect of Class A-2C
Current Interest or a Class A-2C Interest Carry Forward Amount that is recovered
as a voidable preference by a trustee in bankruptcy, less any Non-Supported
Interest Shortfall allocated on such Distribution Date to the Class A-2C
Certificates.

     Class A-2C Interest Carry Forward Amount: As of any Distribution Date, the
sum of (1) the excess of (A) the Class A-2C Current Interest with respect to
prior Distribution Dates over (B) the amount actually distributed to the Class
A-2C Certificates with respect to Current Interest or Interest Carry Forward
Amounts on such prior Distribution Dates and (2) interest on such excess (to the
extent permitted by applicable law) at the Class A-2C Pass-Through Rate for the
related Accrual Period.

     Class A-2C Margin: As of any Distribution Date up to and including the
Auction Termination Date, 0.2500% per annum and, as of any Distribution Date
after the Auction Termination Date, 0.5000% per annum.

     Class A-2C Pass-Through Rate: For the first Distribution Date, 5.57% per
annum. As of any Distribution Date thereafter, the least of (1) One-Month LIBOR
plus the Class A-2C Margin, (2) the Class A-2 Available Funds Cap and (3) the
Class A-2 Maximum Rate Cap for such Distribution Date.

     Class A-2D Certificate: Any Certificate designated as a "Class A-2D
Certificate" on the face thereof, executed by the Trustee and authenticated by
the Authenticating Agent in substantially the form set forth in Exhibit A,
representing the right to distributions as set forth herein.

     Class A-2D Certificate Principal Balance: As of any date of determination,
the aggregate Certificate Principal Balance of the Class A-2D Certificates.

     Class A-2D Current Interest: As of any Distribution Date, the interest
accrued during the related Accrual Period at the Class A-2D Pass-Through Rate on
the Class A-2D Certificate Principal Balance as of such Distribution Date plus
the portion of any previous distributions on such Class in respect of Class A-2D
Current Interest or a Class A-2D Interest Carry Forward Amount that is recovered
as a voidable preference by a trustee in bankruptcy, less any Non-Supported
Interest Shortfall allocated on such Distribution Date to the Class A-2D
Certificates.


                                       20

<PAGE>

     Class A-2D Interest Carry Forward Amount: As of any Distribution Date, the
sum of (1) the excess of (A) the Class A-2D Current Interest with respect to
prior Distribution Dates over (B) the amount actually distributed to the Class
A-2D Certificates with respect to Current Interest or Interest Carry Forward
Amounts on such prior Distribution Dates and (2) interest on such excess (to the
extent permitted by applicable law) at the Class A-2D Pass-Through Rate for the
related Accrual Period.

     Class A-2D Margin: As of any Distribution Date up to and including the
Auction Termination Date, 0.3500% per annum and, as of any Distribution Date
after the Auction Termination Date, 0.7000% per annum.

     Class A-2D Pass-Through Rate: For the first Distribution Date, 5.67% per
annum. As of any Distribution Date thereafter, the least of (1) One-Month LIBOR
plus the Class A-2D Margin, (2) the Class A-2 Available Funds Cap and (3) the
Class A-2 Maximum Rate Cap for such Distribution Date.

     Class B Certificates: The Class B-1 Certificates, Class B-2 Certificates,
and the Class B-3 Certificates.

     Class B-1 Applied Realized Loss Amount: As of any Distribution Date, the
sum of all Applied Realized Loss Amounts with respect to the Mortgage Loans
which have been applied to the reduction of the Certificate Principal Balance of
the Class B-1 Certificates.

     Class B-1 Certificate: Any Certificate designated as a "Class B-1
Certificate" on the face thereof, executed by the Trustee and authenticated by
the Authenticating Agent in substantially the form set forth in Exhibit A,
representing the right to distributions as set forth herein.

     Class B-1 Certificate Principal Balance: As of any date of determination,
the aggregate Certificate Principal Balance of the Class B-1 Certificates.

     Class B-1 Current Interest: As of any Distribution Date, the interest
accrued during the related Accrual Period at the Class B-1 Pass-Through Rate on
the Class B-1 Certificate Principal Balance as of such Distribution Date plus
the portion of any previous distributions on such Class in respect of Class B-1
Current Interest or a Class B-1 Interest Carry Forward Amount that is recovered
as a voidable preference by a trustee in bankruptcy, less any Non-Supported
Interest Shortfall allocated on such Distribution Date to the Class B-1
Certificates.

     Class B-1 Interest Carry Forward Amount: As of any Distribution Date, the
sum of (1) the excess of (A) the Class B-1 Current Interest with respect to
prior Distribution Dates over (B) the amount actually distributed to the Class
B-1 Certificates with respect to Current Interest or Interest Carry Forward
Amounts on such prior Distribution Dates and (2) interest on such excess (to the
extent permitted by applicable law) at the Class B-1 Pass-Through Rate for the
related Accrual Period.

     Class B-1 Margin: As of any Distribution Date up to and including the
Auction Termination Date, 1.4000% per annum and, as of any Distribution Date
after the Auction Termination Date, 2.1000% per annum.

     Class B-1 Pass-Through Rate: For the first Distribution Date, 6.72% per
annum. As of any Distribution Date thereafter, the least of (1) One-Month LIBOR
plus the Class B-1 Margin, (2) the Subordinate Certificate Available Funds Cap
and (3) the Subordinate Certificate Maximum Rate Cap for such Distribution Date.

     Class B-1 Principal Distribution Amount: With respect to any Distribution
Date on or after the Stepdown Date, 100% of the Principal Distribution Amount if
the aggregate Certificate Principal Balance


                                        21

<PAGE>

of the Class A, Class R and Class M Certificates has been reduced to zero and a
Stepdown Trigger Event exists, or, as long as a Stepdown Trigger Event does not
exist, the excess of (1) the sum of (A) the Certificate Principal Balance of the
Class A and Class R Certificates (after taking into account distributions of the
Class A Principal Distribution Amount to the Class A Certificates for such
Distribution Date), (B) the Certificate Principal Balance of the Class M-1
Certificates, Class M-2 Certificates and Class M-3 Certificates (after taking
into account distributions of the Class M-1/M-2/M-3 Principal Distribution
Amount to the Class M-1 Certificates, Class M-2 Certificates and Class M-3
Certificates for such Distribution Date), (C) the Certificate Principal Balance
of the Class M-4 Certificates (after taking into account distributions of the
Class M-4 Principal Distribution Amount to the Class M-4 Certificates for such
Distribution Date), (D) the Certificate Principal Balance of the Class M-5
Certificates (after taking into account distributions of the Class M-5 Principal
Distribution Amount to the Class M-5 Certificates for such Distribution Date),
(E) the Certificate Principal Balance of the Class M-6 Certificates (after
taking into account distributions of the Class M-6 Principal Distribution Amount
to the Class M-6 Certificates for such Distribution Date) and (F) the
Certificate Principal Balance of the Class B-1 Certificates immediately prior to
such Distribution Date over (2) the lesser of (A) approximately 93.00% of the
aggregate Stated Principal Balance of the Mortgage Loans and (B) the excess of
the aggregate Stated Principal Balance of the Mortgage Loans over the Minimum
Required Overcollateralization Amount. Notwithstanding the above, (I) on any
Distribution Date prior to the Stepdown Date on which the aggregate Certificate
Principal Balance of the Class A, Class R and Class M Certificates has been
reduced to zero, the Class B-1 Principal Distribution Amount will equal the
lesser of (x) the outstanding Certificate Principal Balance of the Class B-1
Certificates and (y) 100% of the Principal Distribution Amount remaining after
any distributions on the Class A, Class R and Class M Certificates and (II) in
no event will the Class B-1 Principal Distribution Amount with respect to any
Distribution Date exceed the Certificate Principal Balance of the Class B-1
Certificates.

     Class B-1 Unpaid Realized Loss Amount: As of any Distribution Date, the
excess of (1) the Class B-1 Applied Realized Loss Amount over (2) the sum of (x)
all distributions in reduction of the Class B-1 Unpaid Realized Loss Amounts on
all previous Distribution Dates and (y) all increases in the Certificate
Principal Balance of such Class B-1 Certificates pursuant to the last sentence
of the definition of "Certificate Principal Balance."

     Class B-2 Applied Realized Loss Amount: As of any Distribution Date, the
sum of all Applied Realized Loss Amounts with respect to the Mortgage Loans
which have been applied to the reduction of the Certificate Principal Balance of
the Class B-2 Certificates.

     Class B-2 Certificate: Any Certificate designated as a "Class B-2
Certificate" on the face thereof, executed by the Trustee and authenticated by
the Administrative Agent in substantially the form set forth in Exhibit A,
representing the right to distributions as set forth herein.

     Class B-2 Certificate Principal Balance: As of any date of determination,
the aggregate Certificate Principal Balance of the Class B-2 Certificates.

     Class B-2 Current Interest: As of any Distribution Date, the interest
accrued during the related Accrual Period at the Class B-2 Pass-Through Rate on
the Class B-2 Certificate Principal Balance as of such Distribution Date plus
the portion of any previous distributions on such Class in respect of Class B-2
Current Interest or a Class B-2 Interest Carry Forward Amount that is recovered
as a voidable preference by a trustee in bankruptcy, less any Non-Supported
Interest Shortfall allocated on such Distribution Date to the Class B-2
Certificates.

     Class B-2 Interest Carry Forward Amount: As of any Distribution Date, the
sum of (1) the excess of (A) the Class B-2 Current Interest with respect to
prior Distribution Dates over (B) the amount


                                       22

<PAGE>

actually distributed to the Class B-2 Certificates with respect to Current
Interest or Interest Carry Forward Amounts on such prior Distribution Dates and
(2) interest on such excess (to the extent permitted by applicable law) at the
Class B-2 Pass-Through Rate for the related Accrual Period.

     Class B-2 Margin: As of any Distribution Date up to and including the
Auction Termination Date, 1.4000% per annum and, as of any Distribution Date
after the Auction Termination Date, 2.100% per annum.

     Class B-2 Pass-Through Rate: For the first Distribution Date, 6.72% per
annum. As of any Distribution Date thereafter, the least of (1) One-Month LIBOR
plus the Class B-2 Margin, (2) the Subordinate Certificate Available Funds Cap
and (3) the Subordinate Certificate Maximum Rate Cap for such Distribution Date.

     Class B-2 Principal Distribution Amount: With respect to any Distribution
Date on or after the Stepdown Date, 100% of the Principal Distribution Amount if
the aggregate Certificate Principal Balance of the Class A, Class R, Class M and
Class B-1 Certificates has been reduced to zero and a Stepdown Trigger Event
exists, or, as long as a Stepdown Trigger Event does not exist, the excess of
(1) the sum of (A) the Certificate Principal Balance of the Class A and Class R
Certificates (after taking into account distributions of the Class A Principal
Distribution Amount to the Class A Certificates for such Distribution Date), (B)
the Certificate Principal Balance of the Class M-1 Certificates, Class M-2
Certificates and Class M-3 Certificates (after taking into account distributions
of the Class M-1/M-2/M-3 Principal Distribution Amount to the Class M-1
Certificates, Class M-2 Certificates and Class M-3 Certificates for such
Distribution Date), (C) the Certificate Principal Balance of the Class M-4
Certificates (after taking into account distributions of the Class M-4 Principal
Distribution Amount to the Class M-4 Certificates for such Distribution Date),
(D) the Certificate Principal Balance of the Class M-5 Certificates (after
taking into account distributions of the Class M-5 Principal Distribution Amount
to the Class M-5 Certificates for such Distribution Date), (E) the Certificate
Principal Balance of the Class M-6 Certificates (after taking into account
distributions of the Class M-6 Principal Distribution Amount to the Class M-6
Certificates for such Distribution Date), (F) the Certificate Principal Balance
of the Class B-1 Certificates (after taking into account distributions of the
Class B-1 Principal Distribution Amount to the Class B-1 Certificates for such
Distribution Date) and (G) the Certificate Principal Balance of the Class B-2
Certificates immediately prior to such Distribution Date over (2) the lesser of
(A) approximately 94.40% of the aggregate Stated Principal Balance of the
Mortgage Loans and (B) the excess of the aggregate Stated Principal Balance of
the Mortgage Loans over the Minimum Required Overcollateralization Amount.
Notwithstanding the above, (I) on any Distribution Date prior to the Stepdown
Date on which the aggregate Certificate Principal Balance of the Class A, Class
R, Class M and Class B-1 Certificates has been reduced to zero, the Class B-2
Principal Distribution Amount will equal the lesser of (x) the outstanding
Certificate Principal Balance of the Class B-2 Certificates and (y) 100% of the
Principal Distribution Amount remaining after any distributions on the Class A,
Class R, Class M and Class B-1 Certificates and (II) in no event will the Class
B-2 Principal Distribution Amount with respect to any Distribution Date exceed
the Certificate Principal Balance of the Class B-2 Certificates.

     Class B-2 Unpaid Realized Loss Amount: As of any Distribution Date, the
excess of (1) the Class B-2 Applied Realized Loss Amount over (2) the sum of (x)
all distributions in reduction of the Class B-2 Unpaid Realized Loss Amounts on
all previous Distribution Dates and (y) all increases in the Certificate
Principal Balance of such Class B-2 Certificates pursuant to the last sentence
of the definition of "Certificate Principal Balance."

     Class B-3 Applied Realized Loss Amount: As of any Distribution Date, the
sum of all Applied Realized Loss Amounts with respect to the Mortgage Loans
which have been applied to the reduction of the Certificate Principal Balance of
the Class B-3 Certificates.


                                       23

<PAGE>

     Class B-3 Certificate: Any Certificate designated as a "Class B-3
Certificate" on the face thereof, executed by the Trustee and authenticated by
the Administrative Agent in substantially the form set forth in Exhibit A,
representing the right to distributions as set forth herein.

     Class B-3 Certificate Principal Balance: As of any date of determination,
the aggregate Certificate Principal Balance of the Class B-3 Certificates.

     Class B-3 Current Interest: As of any Distribution Date, the interest
accrued during the related Accrual Period at the Class B-3 Pass-Through Rate on
the Class B-3 Certificate Principal Balance as of such Distribution Date plus
the portion of any previous distributions on such Class in respect of Class B-3
Current Interest or a Class B-3 Interest Carry Forward Amount that is recovered
as a voidable preference by a trustee in bankruptcy, less any Non-Supported
Interest Shortfall allocated on such Distribution Date to the Class B-3
Certificates.

     Class B-3 Interest Carry Forward Amount: As of any Distribution Date, the
sum of (1) the excess of (A) the Class B-3 Current Interest with respect to
prior Distribution Dates over (B) the amount actually distributed to the Class
B-3 Certificates with respect to Current Interest or Interest Carry Forward
Amounts on such prior Distribution Dates and (2) interest on such excess (to the
extent permitted by applicable law) at the Class B-3 Pass-Through Rate for the
related Accrual Period.

     Class B-3 Margin: As of any Distribution Date up to and including the
Auction Termination Date, 1.4000% per annum and, as of any Distribution Date
after the Auction Termination Date, 2.100% per annum.

     Class B-3 Pass-Through Rate: For the first Distribution Date, 6.72% per
annum. As of any Distribution Date thereafter, the least of (1) One-Month LIBOR
plus the Class B-3 Margin, (2) the Subordinate Certificate Available Funds Cap
and (3) the Subordinate Certificate Maximum Rate Cap for such Distribution Date.

     Class B-3 Principal Distribution Amount: With respect to any Distribution
Date on or after the Stepdown Date, 100% of the Principal Distribution Amount if
the aggregate Certificate Principal Balance of the Class A, Class R, Class M,
Class B-1 and Class B-2 Certificates has been reduced to zero and a Stepdown
Trigger Event exists, or, as long as a Stepdown Trigger Event does not exist,
the excess of (1) the sum of (A) the Certificate Principal Balance of the Class
A and Class R Certificates (after taking into account distributions of the Class
A Principal Distribution Amount to the Class A Certificates for such
Distribution Date), (B) the Certificate Principal Balance of the Class M-1
Certificates, Class M-2 Certificates and Class M-3 Certificates (after taking
into account distributions of the Class M-1/M-2/M-3 Principal Distribution
Amount to the Class M-1 Certificates, Class M-2 Certificates and Class M-3
Certificates for such Distribution Date), (C) the Certificate Principal Balance
of the Class M-4 Certificates (after taking into account distributions of the
Class M-4 Principal Distribution Amount to the Class M-4 Certificates for such
Distribution Date), (D) the Certificate Principal Balance of the Class M-5
Certificates (after taking into account distributions of the Class M-5 Principal
Distribution Amount to the Class M-5 Certificates for such Distribution Date),
(E) the Certificate Principal Balance of the Class M-6 Certificates (after
taking into account distributions of the Class M-6 Principal Distribution Amount
to the Class M-6 Certificates for such Distribution Date), (F) the Certificate
Principal Balance of the Class B-1 Certificates (after taking into account
distributions of the Class B-1 Principal Distribution Amount to the Class B-1
Certificates for such Distribution Date), (G) the Certificate Principal Balance
of the Class B-2 Certificates (after taking into account distributions of the
Class B-2 Principal Distribution Amount to the Class B-2 Certificates for such
Distribution Date) and (H) the Certificate Principal Balance of the Class B-3
Certificates immediately prior to such Distribution Date over (2) the lesser of
(A) approximately 96.40% of the aggregate Stated Principal Balance of the
Mortgage Loans and (B) the excess of the


                                       24

<PAGE>

aggregate Stated Principal Balance of the Mortgage Loans over the Minimum
Required Overcollateralization Amount. Notwithstanding the above, (I) on any
Distribution Date prior to the Stepdown Date on which the aggregate Certificate
Principal Balance of the Class A, Class R, Class M, Class B-1 and Class B-2
Certificates has been reduced to zero, the Class B-3 Principal Distribution
Amount will equal the lesser of (x) the outstanding Certificate Principal
Balance of the Class B-3 Certificates and (y) 100% of the Principal Distribution
Amount remaining after any distributions on the Class A, Class R, Class M, Class
B-1 and Class B-2 Certificates and (II) in no event will the Class B-3 Principal
Distribution Amount with respect to any Distribution Date exceed the Certificate
Principal Balance of the Class B-3 Certificates.

     Class B-3 Unpaid Realized Loss Amount: As of any Distribution Date, the
excess of (1) the Class B-3 Applied Realized Loss Amount over (2) the sum of (x)
all distributions in reduction of the Class B-3 Unpaid Realized Loss Amounts on
all previous Distribution Dates and (y) all increases in the Certificate
Principal Balance of such Class B-3 Certificates pursuant to the last sentence
of the definition of "Certificate Principal Balance."

     Class C Applied Realized Loss Amount: As of any Distribution Date, the sum
of all Applied Realized Loss Amounts with respect to the Mortgage Loans which
have been applied to the reduction of the Certificate Principal Balance of the
Class C Certificates.

     Class C Certificate: Any Certificate designated as a "Class C Certificate"
on the face thereof, executed by the Trustee and authenticated by the
Administrative Agent in substantially the form set forth in Exhibit A,
representing the right to distributions as set forth herein.

     Class C Certificate Principal Balance: As of any date of determination, the
aggregate Certificate Principal Balance of the Class C Certificates.

     Class C Current Interest: As of any Distribution Date, the interest accrued
during the related Accrual Period at the Class C Distributable Interest Rate on
a notional amount equal to the aggregate principal balance of the Lower Tier
REMIC Regular Interests immediately prior to such Distribution Date plus the
interest portion of any previous distributions on such Class that is recovered
as a voidable preference by a trustee in bankruptcy, less any Non-Supported
Interest Shortfall allocated on such Distribution Date to the Class C
Certificates.

     Class C Distributable Interest Rate: The excess, if any, of (a) the
weighted average of the interest rates on the Lower Tier REMIC Regular Interests
(other than the Class LT-IO Interest) over (b) two times the weighted average of
the interest rates on the Lower Tier REMIC I Marker Interests and the Class LTIX
Interest (treating for purposes of this clause (b) the interest rate on each of
the Lower Tier REMIC I Marker Interests as being subject to a cap and a floor
equal to the interest rate of the Corresponding REMIC Regular Interest of the
Corresponding Certificates (as adjusted, if necessary, for the length of the
Accrual Period for the LIBOR Certificates) and treating the Class LTIX Interest
as being capped at zero). The averages described in the preceding sentence shall
be weighted on the basis of the respective principal balances of the Lower Tier
REMIC Regular Interests immediately prior to any date of determination.

     Class C Interest Carry Forward Amount: As of any Distribution Date, the
excess of (A) the Class C Current Interest with respect to prior Distribution
Dates over (B) the amount actually distributed to the Class C Certificates with
respect to interest on such prior Distribution Dates or added to the aggregate
Certificate Principal Balance of the Class C Certificates (other than amounts so
added attributable to Subsequent Recoveries or proceeds of the Swap Agreement).


                                       25

<PAGE>

     Class C Unpaid Realized Loss Amount: As of any Distribution Date, the
excess of (1) the Class C Applied Realized Loss Amount over (2) the sum of (x)
all distributions in reduction of the Class C Unpaid Realized Loss Amount on all
previous Distribution Dates and (y) all increases in the Certificate Principal
Balance of such Class C Certificates (A) pursuant to the last sentence of the
definition of "Certificate Principal Balance" or (B) attributable to
distributions of proceeds of the Swap Agreement.

     Class LTA-1 Interest: An uncertificated regular interest in the Lower Tier
REMIC with an initial principal balance equal to 1/4 of the initial principal
balance of its Corresponding Certificates and an interest rate equal to the Net
Rate.

     Class LTA-2A Interest: An uncertificated regular interest in the Lower Tier
REMIC with an initial principal balance equal to 1/4 of the initial principal
balance of its Corresponding Certificate and an interest rate equal to the Net
Rate.

     Class LTA-2B Interest: An uncertificated regular interest in the Lower Tier
REMIC with an initial principal balance equal to 1/4 of the initial principal
balance of its Corresponding Certificate and an interest rate equal to the Net
Rate.

     Class LTA-2C Interest: An uncertificated regular interest in the Lower Tier
REMIC with an initial principal balance equal to 1/4 of the initial principal
balance of its Corresponding Certificate and an interest rate equal to the Net
Rate.

     Class LTA-2D Interest: An uncertificated regular interest in the Lower Tier
REMIC with an initial principal balance equal to 1/4 of the initial principal
balance of its Corresponding Certificate and an interest rate equal to the Net
Rate.

     Class LTB-1 Interest: An uncertificated regular interest in the Lower Tier
REMIC with an initial principal balance equal to 1/4 of the initial principal
balance of its Corresponding Certificate and an interest rate equal to the Net
Rate.

     Class LTB-2 Interest: An uncertificated regular interest in the Lower Tier
REMIC with an initial principal balance equal to 1/4 of the initial principal
balance of its Corresponding Certificate and an interest rate equal to the Net
Rate.

      Class LTB-3 Interest: An uncertificated regular interest in the Lower Tier
REMIC with an initial principal balance equal to 1/4 of the initial principal
balance of its Corresponding Certificate and an interest rate equal to the Net
Rate.

     Class LT-IO Interest: An uncertificated regular interest in the Lower Tier
REMIC with the characteristics set forth in the description of the Lower Tier
REMIC in the Preliminary Statement.

     Class LTII1A Interest: An uncertificated regular interest in the Lower Tier
REMIC with an initial principal balance equal to 0.05% of the excess of (i) the
aggregate Cut-off Date Principal Balance of the Group One Mortgage Loans over
(ii) the aggregate of the initial Certificate Principal Balances of Certificate
Group One, and with an interest rate equal to the Net Rate.

     Class LTII1B Interest: An uncertificated regular interest in the Lower Tier
REMIC with an initial principal balance equal to 0.05% of the aggregate Cut-off
Date Principal Balance of the Group One Mortgage Loans, and with an interest
rate equal to the rate set forth in footnote 9 to the description of the Lower
Tier REMIC in the Preliminary Statement.


                                       26

<PAGE>

     Class LTII2A Interest: An uncertificated regular interest in the Lower Tier
REMIC with an initial principal balance equal to 0.05% of the excess of (i) the
aggregate Cut-off Date Principal Balance of the Group Two Mortgage Loans over
(ii) the aggregate of the initial Certificate Principal Balances of Certificate
Group Two, and with an interest rate equal to the Net Rate.

     Class LTII2B Interest: An uncertificated regular interest in the Lower Tier
REMIC with an initial principal balance equal to 0.05% of the aggregate Cut-off
Date Principal Balance of the Group Two Mortgage Loans, and with an interest
rate equal to the rate set forth in footnote 10 to the description of the Lower
Tier REMIC in the Preliminary Statement.

     Class LTIX Interest: An uncertificated regular interest in the Lower Tier
REMIC with an initial principal balance equal to the excess of (i) 50% of the
aggregate Cut-off Date Principal Balance of the Mortgage Loans over (ii) the
initial principal balance of the Lower Tier REMIC I Marker Interests, and with
an interest rate equal to the Net Rate.

     Class LTIIX Interest: An uncertificated regular interest in the Lower Tier
REMIC with an initial principal balance equal to the excess of (i) 50% of the
aggregate Cut-off Date Principal Balance of the Mortgage Loans over (ii) the
initial principal balance of the Lower Tier REMIC II Marker Interests, and with
an interest rate equal to the Net Rate.

     Class LTM-1 Interest: An uncertificated regular interest in the Lower Tier
REMIC with an initial principal balance equal to 1/4 of the initial principal
balance of its Corresponding Certificate and an interest rate equal to the Net
Rate.

     Class LTM-2 Interest: An uncertificated regular interest in the Lower Tier
REMIC with an initial principal balance equal to 1/4 of the initial principal
balance of its Corresponding Certificate and an interest rate equal to the Net
Rate.

     Class LTM-3 Interest: An uncertificated regular interest in the Lower Tier
REMIC with an initial principal balance equal to 1/4 of the initial principal
balance of its Corresponding Certificate and an interest rate equal to the Net
Rate.

     Class LTM-4 Interest: An uncertificated regular interest in the Lower Tier
REMIC with an initial principal balance equal to 1/4 of the initial principal
balance of its Corresponding Certificate and an interest rate equal to the Net
Rate.

     Class LTM-5 Interest: An uncertificated regular interest in the Lower Tier
REMIC with an initial principal balance equal to 1/4 of the initial principal
balance of its Corresponding Certificate and an interest rate equal to the Net
Rate.

     Class LTM-6 Interest: An uncertificated regular interest in the Lower Tier
REMIC with an initial principal balance equal to 1/4 of the initial principal
balance of its Corresponding Certificate and an interest rate equal to the Net
Rate.

     Class LTR Interest: The sole class of "residual interest" in the Lower Tier
REMIC.

     Class M Certificates: Any of the Class M-1, Class M-2, Class M-3, Class
M-4, Class M-5 and Class M-6 Certificates.


                                       27

<PAGE>

     Class M-1 Applied Realized Loss Amount: As of any Distribution Date, the
sum of all Applied Realized Loss Amounts with respect to the Mortgage Loans
which have been applied to the reduction of the Certificate Principal Balance of
the Class M-1 Certificates.

     Class M-1 Certificate: Any Certificate designated as a "Class M-1
Certificate" on the face thereof, executed by the Trustee and authenticated by
the Administrative Agent in substantially the form set forth in Exhibit A,
representing the right to distributions as set forth herein.

     Class M-1 Certificate Principal Balance: As of any date of determination,
the aggregate Certificate Principal Balance of the Class M-1 Certificates.

     Class M-1 Current Interest: As of any Distribution Date, the interest
accrued during the related Accrual Period at the Class M-1 Pass-Through Rate on
the Class M-1 Certificate Principal Balance as of such Distribution Date plus
the portion of any previous distributions on such Class in respect of Class M-1
Current Interest or a Class M-1 Interest Carry Forward Amount that is recovered
as a voidable preference by a trustee in bankruptcy, less any Non-Supported
Interest Shortfall allocated on such Distribution Date to the Class M-1
Certificates.

     Class M-1 Interest Carry Forward Amount: As of any Distribution Date, the
sum of (1) the excess of (A) the Class M-1 Current Interest with respect to
prior Distribution Dates over (B) the amount actually distributed to the Class
M-1 Certificates with respect to Current Interest or Interest Carry Forward
Amounts on such prior Distribution Dates and (2) interest on such excess (to the
extent permitted by applicable law) at the Class M-1 Pass-Through Rate for the
related Accrual Period.

     Class M-1 Margin: As of any Distribution Date up to and including the
Auction Termination Date, 0.4000% per annum and, as of any Distribution Date
after the Auction Termination Date, 0.6000% per annum.

     Class M-1 Pass-Through Rate: For the first Distribution Date, 5.72% per
annum. As of any Distribution Date thereafter, the least of (1) One-Month LIBOR
plus the Class M-1 Margin and (2) the Subordinate Certificate Available Funds
Cap and (3) the Subordinate Certificate Maximum Rate Cap for such Distribution
Date.

     Class M-1/M-2/M-3 Principal Distribution Amount: With respect to any
Distribution Date on or after the Stepdown Date, 100% of the Principal
Distribution Amount for such Distribution Date if the Certificate Principal
Balances of the Class A and Class R Certificates have been reduced to zero and a
Stepdown Trigger Event exists, or as long as a Stepdown Trigger Event does not
exist, the excess of (1) the sum of (A) the Certificate Principal Balances of
the Class A and Class R Certificates (after taking into account distributions of
the Class A Principal Distribution Amount to the Class A Certificates for such
Distribution Date) and (B) the Class M-1 Certificate Principal Balance, the
Class M-2 Certificate Principal Balance and the Class M-3 Certificate Principal
Balance immediately prior to such Distribution Date over (2) the lesser of (A)
84.80% of the Stated Principal Balances of the Mortgage Loans and (B) the excess
of the Stated Principal Balances for the Mortgage Loans over the Minimum
Required Overcollateralization Amount. Notwithstanding the foregoing, (I) on any
Distribution Date prior to the Stepdown Date on which the Certificate Principal
Balance of each Class of the Class A Certificate and Class R Certificate has
been reduced to zero, the Class M-1/M-2/M-3 Principal Distribution Amount will
equal the lesser of (x) the outstanding Certificate Principal Balance of the
Class M-1, Class M-2 and Class M-3 Certificates and (y) 100% of the Principal
Distribution Amount remaining after any distributions on such Class A
Certificates and Class R Certificate and (II) in no event will the Class
M-1/M-2/M-3 Principal Distribution Amount with respect to any Distribution Date
exceed the Class M-1, Class M-2 and Class M-3 Certificate Principal Balance.


                                       28

<PAGE>

     Class M-1 Unpaid Realized Loss Amount: As of any Distribution Date, the
excess of (1) the Class M-1 Applied Realized Loss Amount over (2) the sum of (x)
all distributions in reduction of the Class M-1 Unpaid Realized Loss Amounts on
all previous Distribution Dates and (y) all increases in the Certificate
Principal Balance of such Class M-1 Certificates pursuant to the last sentence
of the definition of "Certificate Principal Balance."

     Class M-2 Applied Realized Loss Amount: As of any Distribution Date, the
sum of all Applied Realized Loss Amounts with respect to the Mortgage Loans
which have been applied to the reduction of the Certificate Principal Balance of
the Class M-2 Certificates.

     Class M-2 Certificate: Any Certificate designated as a "Class M-2
Certificate" on the face thereof, executed by the Trustee and authenticated by
the Administrative Agent in substantially the form set forth in Exhibit A,
representing the right to distributions as set forth herein.

     Class M-2 Certificate Principal Balance: As of any date of determination,
the aggregate Certificate Principal Balance of the Class M-2 Certificates.

     Class M-2 Current Interest: As of any Distribution Date, the interest
accrued during the related Accrual Period at the Class M-2 Pass-Through Rate on
the Class M-2 Certificate Principal Balance as of such Distribution Date plus
the portion of any previous distributions on such Class in respect of Class M-2
Current Interest or a Class M-2 Interest Carry Forward Amount that is recovered
as a voidable preference by a trustee in bankruptcy, less any Non-Supported
Interest Shortfall allocated on such Distribution Date to the Class M-2
Certificates.

     Class M-2 Interest Carry Forward Amount: As of any Distribution Date, the
sum of (1) the excess of (A) the Class M-2 Current Interest with respect to
prior Distribution Dates over (B) the amount actually distributed to the Class
M-2 Certificates with respect to Current Interest or Interest Carry Forward
Amounts on such prior Distribution Dates and (2) interest on such excess (to the
extent permitted by applicable law) at the Class M-2 Pass-Through Rate for the
related Accrual Period.

     Class M-2 Margin: As of any Distribution Date up to and including the
Auction Termination Date, 0.5500% per annum and, as of any Distribution Date
after the Auction Termination Date, 0.8250% per annum.

     Class M-2 Pass-Through Rate: For the first Distribution Date, 5.87% per
annum. As of any Distribution Date thereafter, the least of (1) One-Month LIBOR
plus the Class M-2 Margin, (2) the Subordinate Certificate Available Funds Cap
and (3) the Subordinate Certificate Maximum Rate Cap for such Distribution Date.

     Class M-2 Unpaid Realized Loss Amount: As of any Distribution Date, the
excess of (1) the Class M-2 Applied Realized Loss Amount over (2) the sum of (x)
all distributions in reduction of the Class M-2 Unpaid Realized Loss Amounts on
all previous Distribution Dates and (y) all increases in the Certificate
Principal Balance of such Class M-2 Certificates pursuant to the last sentence
of the definition of "Certificate Principal Balance."

     Class M-3 Applied Realized Loss Amount: As of any Distribution Date, the
sum of all Applied Realized Loss Amounts with respect to the Mortgage Loans
which have been applied to the reduction of the Certificate Principal Balance of
the Class M-3 Certificates.


                                       29

<PAGE>

     Class M-3 Certificate: Any Certificate designated as a "Class M-3
Certificate" on the face thereof, executed by the Trustee and authenticated by
the Administrative Agent in substantially the form set forth in Exhibit A,
representing the right to distributions as set forth herein.

     Class M-3 Certificate Principal Balance: As of any date of determination,
the aggregate Certificate Principal Balance of the Class M-3 Certificates.

     Class M-3 Current Interest: As of any Distribution Date, the interest
accrued during the related Accrual Period at the Class M-3 Pass-Through Rate on
the Class M-3 Certificate Principal Balance as of such Distribution Date plus
the portion of any previous distributions on such Class in respect of Class M-3
Current Interest or a Class M-3 Interest Carry Forward Amount that is recovered
as a voidable preference by a trustee in bankruptcy, less any Non-Supported
Interest Shortfall allocated on such Distribution Date to the Class M-3
Certificates.

     Class M-3 Interest Carry Forward Amount: As of any Distribution Date, the
sum of (1) the excess of (A) the Class M-3 Current Interest with respect to
prior Distribution Dates over (B) the amount actually distributed to the Class
M-3 Certificates with respect to Current Interest or Interest Carry Forward
Amounts on such prior Distribution Dates and (2) interest on such excess (to the
extent permitted by applicable law) at the Class M-3 Pass-Through Rate for the
related Accrual Period.

     Class M-3 Margin: As of any Distribution Date up to and including the
Auction Termination Date, 0.7500% per annum and, as of any Distribution Date
after the Auction Termination Date, 1.1250% per annum.

     Class M-3 Pass-Through Rate: For the first Distribution Date, 6.07% per
annum. As of any Distribution Date thereafter, the least of (1) One-Month LIBOR
plus the Class M-3 Margin, (2) the Subordinate Certificate Available Funds Cap
and (3) the Subordinate Certificate Maximum Rate Cap for such Distribution Date.

     Class M-3 Unpaid Realized Loss Amount: As of any Distribution Date, the
excess of (1) the Class M-3 Applied Realized Loss Amount over (2) the sum of (x)
all distributions in reduction of the Class M-3 Unpaid Realized Loss Amounts on
all previous Distribution Dates and (y) all increases in the Certificate
Principal Balance of such Class M-3 Certificates pursuant to the last sentence
of the definition of "Certificate Principal Balance."

     Class M-4 Applied Realized Loss Amount: As of any Distribution Date, the
sum of all Applied Realized Loss Amounts with respect to the Mortgage Loans
which have been applied to the reduction of the Certificate Principal Balance of
the Class M-4 Certificates.

     Class M-4 Certificate: Any Certificate designated as a "Class M-4
Certificate" on the face thereof, executed by the Trustee and authenticated by
the Administrative Agent in substantially the form set forth in Exhibit A,
representing the right to distributions as set forth herein.

     Class M-4 Certificate Principal Balance: As of any date of determination,
the aggregate Certificate Principal Balance of the Class M-4 Certificates.

     Class M-4 Current Interest: As of any Distribution Date, the interest
accrued during the related Accrual Period at the Class M-4 Pass-Through Rate on
the Class M-4 Certificate Principal Balance as of such Distribution Date plus
the portion of any previous distributions on such Class in respect of Class M-4
Current Interest or a Class M-4 Interest Carry Forward Amount that is recovered
as a voidable


                                        30

<PAGE>

preference by a trustee in bankruptcy, less any Non-Supported Interest Shortfall
allocated on such Distribution Date to the Class M-4 Certificates.

     Class M-4 Interest Carry Forward Amount: As of any Distribution Date, the
sum of (1) the excess of (A) the Class M-4 Current Interest with respect to
prior Distribution Dates over (B) the amount actually distributed to the Class
M-4 Certificates with respect to Current Interest or Interest Carry Forward
Amounts on such prior Distribution Dates and (2) interest on such excess (to the
extent permitted by applicable law) at the Class M-4 Pass-Through Rate for the
related Accrual Period.

     Class M-4 Margin: As of any Distribution Date up to and including the
Auction Termination Date, 1.0000% per annum and, as of any Distribution Date
after the Auction Termination Date, 1.5000% per annum.

     Class M-4 Pass-Through Rate: For the first Distribution Date, 6.32% per
annum. As of any Distribution Date thereafter, the least of (1) One-Month LIBOR
plus the Class M-4 Margin, (2) the Subordinate Certificate Available Funds Cap
and (3) the Subordinate Certificate Maximum Rate Cap for such Distribution Date.

     Class M-4 Principal Distribution Amount: With respect to any Distribution
Date on or after the Stepdown Date, 100% of the Principal Distribution Amount
for such Distribution Date if the Certificate Principal Balances of the Class A,
Class R, Class M-1, Class M-2 and Class M-3 Certificates have been reduced to
zero and a Stepdown Trigger Event exists, or as long as a Stepdown Trigger Event
does not exist, the excess of (1) the sum of (A) the Certificate Principal
Balances of the Class A and Class R Certificates (after taking into account
distributions of the Class A Principal Distribution Amount on such Distribution
Date), (B) the Class M-1 Certificate Principal Balance, the Class M-2
Certificate Principal Balance and the Class M-3 Certificate Principal Balance
(after taking into account distributions of the Class M-1/M-2/M-3 Principal
Distribution Amount on such Distribution Date) and (C) the Class M-4 Certificate
Principal Balance immediately prior to such Distribution Date over (2) the
lesser of (A) 87.20% of the Stated Principal Balances of the Mortgage Loans and
(B) the excess of the Stated Principal Balances for the Mortgage Loans over the
Minimum Required Overcollateralization Amount. Notwithstanding the foregoing,
(I) on any Distribution Date prior to the Stepdown Date on which the Certificate
Principal Balance of each Class of the Class A Certificates, the Class R
Certificate, the Class M-1 Certificates, the Class M-2 and the Class M-3
Certificates has been reduced to zero, the Class M-4 Principal Distribution
Amount will equal the lesser of (x) the outstanding Certificate Principal
Balance of the Class M-3 Certificates and (y) 100% of the Principal Distribution
Amount remaining after any distributions on such Class A, Class R, Class M-1,
Class M-2 and Class M-3 Certificates and (II) in no event will the Class M-4
Principal Distribution Amount with respect to any Distribution Date exceed the
Class M-4 Certificate Principal Balance.

     Class M-4 Unpaid Realized Loss Amount: As of any Distribution Date, the
excess of (1) the Class M-4 Applied Realized Loss Amount over (2) the sum of (x)
all distributions in reduction of the Class M-4 Unpaid Realized Loss Amounts on
all previous Distribution Dates and (y) all increases in the Certificate
Principal Balance of such Class M-4 Certificates pursuant to the last sentence
of the definition of "Certificate Principal Balance."

     Class M-5 Applied Realized Loss Amount: As of any Distribution Date, the
sum of all Applied Realized Loss Amounts with respect to the Mortgage Loans
which have been applied to the reduction of the Certificate Principal Balance of
the Class M-5 Certificates.


                                       31
<PAGE>

     Class M-5 Certificate: Any Certificate designated as a "Class M-5
Certificate" on the face thereof, executed by the Trustee and authenticated by
the Administrative Agent in substantially the form set forth in Exhibit A,
representing the right to distributions as set forth herein.

     Class M-5 Certificate Principal Balance: As of any date of determination,
the aggregate Certificate Principal Balance of the Class M-5 Certificates.

     Class M-5 Current Interest: As of any Distribution Date, the interest
accrued during the related Accrual Period at the Class M-5 Pass-Through Rate on
the Class M-5 Certificate Principal Balance as of such Distribution Date plus
the portion of any previous distributions on such Class in respect of Class M-5
Current Interest or a Class M-5 Interest Carry Forward Amount that is recovered
as a voidable preference by a trustee in bankruptcy, less any Non-Supported
Interest Shortfall allocated on such Distribution Date to the Class M-5
Certificates.

     Class M-5 Interest Carry Forward Amount: As of any Distribution Date, the
sum of (1) the excess of (A) the Class M-5 Current Interest with respect to
prior Distribution Dates over (B) the amount actually distributed to the Class
M-5 Certificates with respect to Current Interest or Interest Carry Forward
Amounts on such prior Distribution Dates and (2) interest on such excess (to the
extent permitted by applicable law) at the Class M-5 Pass-Through Rate for the
related Accrual Period.

     Class M-5 Margin: As of any Distribution Date up to and including the
Auction Termination Date, 1.3000% per annum and, as of any Distribution Date
after the Auction Termination Date, 1.9500% per annum.

     Class M-5 Pass-Through Rate: For the first Distribution Date, 6.62% per
annum. As of any Distribution Date thereafter, the least of (1) One-Month LIBOR
plus the Class M-5 Margin, (2) the Subordinate Certificate Available Funds Cap
and (3) the Subordinate Certificate Maximum Rate Cap for such Distribution Date.

     Class M-5 Principal Distribution Amount: With respect to any Distribution
Date on or after the Stepdown Date, 100% of the Principal Distribution Amount
for such Distribution Date if the Certificate Principal Balances of the Class A,
Class R, Class M-1, Class M-2, Class M-3 and Class M-4 Certificates have been
reduced to zero and a Stepdown Trigger Event exists, or as long as a Stepdown
Trigger Event does not exist, the excess of (1) the sum of (A) the Certificate
Principal Balances of the Class A and Class R Certificates (after taking into
account distributions of the Class A Principal Distribution Amount on such
Distribution Date), (B) the Class M-1 Certificate Principal Balance, the Class
M-2 Certificate Principal Balance and the Class M-3 Certificate Principal
Balance (after taking into account distributions of the Class M-1/M-2/M-3
Principal Distribution Amount on such Distribution Date), (C) the Class M-4
Certificate Principal Balance (after taking into account distributions of the
Class M-4 Principal Distribution Amount on such Distribution Date) and (D) the
Class M-5 Certificate Principal Balance immediately prior to such Distribution
Date over (2) the lesser of (A) 89.20% of the Stated Principal Balances of the
Mortgage Loans and (B) the excess of the Stated Principal Balances for the
Mortgage Loans over the Minimum Required Overcollateralization Amount.
Notwithstanding the foregoing, (I) on any Distribution Date prior to the
Stepdown Date on which the Certificate Principal Balance of each Class of the
Class A Certificates, the Class R Certificate, the Class M-1 Certificates, the
Class M-2, the Class M-3 and the Class M-4 Certificates has been reduced to
zero, the Class M-5 Principal Distribution Amount will equal the lesser of (x)
the outstanding Certificate Principal Balance of the Class M-5 Certificates and
(y) 100% of the Principal Distribution Amount remaining after any distributions
on such Class A, Class R, Class M-1, Class M-2, Class M-3 and Class M-4
Certificates and (II) in no event will the Class M-5 Principal Distribution
Amount with respect to any Distribution Date exceed the Class M-5 Certificate
Principal Balance.


                                       32

<PAGE>

     Class M-5 Unpaid Realized Loss Amount: As of any Distribution Date, the
excess of (1) the Class M-5 Applied Realized Loss Amount over (2) the sum of (x)
all distributions in reduction of the Class M-5 Unpaid Realized Loss Amounts on
all previous Distribution Dates and (y) all increases in the Certificate
Principal Balance of such Class M-5 Certificates pursuant to the last sentence
of the definition of "Certificate Principal Balance."

     Class M-6 Applied Realized Loss Amount: As of any Distribution Date, the
sum of all Applied Realized Loss Amounts with respect to the Mortgage Loans
which have been applied to the reduction of the Certificate Principal Balance of
the Class M-6 Certificates.

     Class M-6 Certificate: Any Certificate designated as a "Class M-6
Certificate" on the face thereof, executed by the Trustee and authenticated by
the Administrative Agent in substantially the form set forth in Exhibit A,
representing the right to distributions as set forth herein.

     Class M-6 Certificate Principal Balance: As of any date of determination,
the aggregate Certificate Principal Balance of the Class M-6 Certificates.

     Class M-6 Current Interest: As of any Distribution Date, the interest
accrued during the related Accrual Period at the Class M-6 Pass-Through Rate on
the Class M-6 Certificate Principal Balance as of such Distribution Date plus
the portion of any previous distributions on such Class in respect of Class M-6
Current Interest or a Class M-6 Interest Carry Forward Amount that is recovered
as a voidable preference by a trustee in bankruptcy, less any Non-Supported
Interest Shortfall allocated on such Distribution Date to the Class M-6
Certificates.

     Class M-6 Interest Carry Forward Amount: As of any Distribution Date, the
sum of (1) the excess of (A) the Class M-6 Current Interest with respect to
prior Distribution Dates over (B) the amount actually distributed to the Class
M-6 Certificates with respect to Current Interest or Interest Carry Forward
Amounts on such prior Distribution Dates and (2) interest on such excess (to the
extent permitted by applicable law) at the Class M-6 Pass-Through Rate for the
related Accrual Period.

     Class M-6 Margin: As of any Distribution Date up to and including the
Auction Termination Date, 1.4000% per annum and, as of any Distribution Date
after the Auction Termination Date, 2.1000% per annum.

     Class M-6 Pass-Through Rate: For the first Distribution Date, 6.72% per
annum. As of any Distribution Date thereafter, the least of (1) One-Month LIBOR
plus the Class M-6 Margin, (2) the Subordinate Certificate Available Funds Cap
and (3) the Subordinate Certificate Maximum Rate Cap for such Distribution Date.

     Class M-6 Principal Distribution Amount: With respect to any Distribution
Date on or after the Stepdown Date, 100% of the Principal Distribution Amount
for such Distribution Date if the Certificate Principal Balances of the Class A,
Class R, Class M-1, Class M-2, Class M-3, Class M-4 and Class M-5 Certificates
have been reduced to zero and a Stepdown Trigger Event exists, or as long as a
Stepdown Trigger Event does not exist, the excess of (1) the sum of (A) the
Certificate Principal Balances of the Class A and Class R Certificates (after
taking into account distributions of the Class A Principal Distribution Amount
on such Distribution Date), (B) the Class M-1 Certificate Principal Balance, the
Class M-2 Certificate Principal Balance and the Class M-3 Certificate Principal
Balance (after taking into account distributions of the Class M-1/M-2/M-3
Principal Distribution Amount on such Distribution Date), (C) the Class M-4
Certificate Principal Balance (after taking into account distributions of the
Class M-4 Principal Distribution Amount on such Distribution Date), (D) the
Class M-5 Certificate Principal Balance (after taking into account distributions
of the Class M-5 Principal Distribution Amount on such


                                       33

<PAGE>

Distribution Date) and (E) the Class M-6 Certificate Principal Balance
immediately prior to such Distribution Date over (2) the lesser of (A) 91.20% of
the Stated Principal Balances of the Mortgage Loans and (B) the excess of the
Stated Principal Balances for the Mortgage Loans over the Minimum Required
Overcollateralization Amount. Notwithstanding the foregoing, (I) on any
Distribution Date prior to the Stepdown Date on which the Certificate Principal
Balance of each Class of the Class A Certificates, the Class R Certificate, the
Class M-1 Certificates, the Class M-2, the Class M-3, the Class M-4 and the
Class M-5 Certificates has been reduced to zero, the Class M-6 Principal
Distribution Amount will equal the lesser of (x) the outstanding Certificate
Principal Balance of the Class M-6 Certificates and (y) 100% of the Principal
Distribution Amount remaining after any distributions on such Class A, Class R,
Class M-1, Class M-2, Class M-3, Class M-4 and Class M-5 Certificates and (II)
in no event will the Class M-6 Principal Distribution Amount with respect to any
Distribution Date exceed the Class M-6 Certificate Principal Balance.

     Class M-6 Unpaid Realized Loss Amount: As of any Distribution Date, the
excess of (1) the Class M-6 Applied Realized Loss Amount over (2) the sum of (x)
all distributions in reduction of the Class M-6 Unpaid Realized Loss Amounts on
all previous Distribution Dates and (y) all increases in the Certificate
Principal Balance of such Class M-6 Certificates pursuant to the last sentence
of the definition of "Certificate Principal Balance."

     Class P Certificate: Any Certificate designated as a "Class P Certificate"
on the face thereof, executed by the Trustee and authenticated by the
Administrative Agent in substantially the form set forth in Exhibit A,
representing the right to distributions as set forth herein.

      Class R Certificate: Any Certificate designated as a "Class R Certificate"
on the face thereof, executed by the Trustee and authenticated by the
Administrative Agent in substantially the form set forth in Exhibit A,
representing the right to distributions as set forth herein.

     Class R Certificate Principal Balance: As of any date of determination, the
aggregate Certificate Principal Balance of the Class R Certificate.

     Class R Current Interest: As of any Distribution Date, the interest accrued
during the related Accrual Period at the Class R Pass-Through Rate on the Class
R Certificate Principal Balance as of such Distribution Date plus the portion of
any previous distributions on such Class in respect of Class R Current Interest
or a Class R Interest Carry Forward Amount that is recovered as a voidable
preference by a trustee in bankruptcy, less any Non-Supported Interest Shortfall
allocated on such Distribution Date to the Class R Certificate.

     Class R Interest Carry Forward Amount: As of any Distribution Date, the sum
of (1) the excess of (A) the Class R Current Interest with respect to prior
Distribution Dates over (B) the amount actually distributed to the Class R
Certificate with respect to Current Interest or Interest Carry Forward Amounts
on such prior Distribution Dates and (2) interest on such excess (to the extent
permitted by applicable law) at the Class R Pass-Through Rate for the related
Accrual Period.

     Class R Margin: As of any Distribution Date up to and including the Auction
Termination Date, 0.240% per annum and, as of any Distribution Date after the
Auction Termination Date, 0.480% per annum.

     Class R Pass-Through Rate: For the first Distribution Date, 5.56% per
annum. As of any Distribution Date thereafter, the least of (1) One-Month LIBOR
plus the Class R Margin, (2) the Class A-1 Available Funds Cap for such
Distribution Date and (3) the Class A-1 Maximum Rate Cap.


                                       34

<PAGE>

     Class SWR Interest: The sole class of "residual interest" in the SWAP
REMIC.

     Clean Up Call: The termination of the Trust Fund hereunder pursuant to
Section 9.01(a)(ii).

     Clean Up Call Date: The second Distribution Date immediately following the
Auction Termination Date.

     Clean Up Call Price: An amount equal to the sum of (a) the aggregate Stated
Principal Balance of each Mortgage Loan (other than any Mortgage Loan that is an
REO Property), plus accrued interest thereon at the applicable Mortgage Rate
through the Due Date preceding distribution of the proceeds, (b) the fair market
value of any REO Property, plus accrued interest thereon, (c) any unreimbursed
fees, out-of-pocket expenses owed to the Trustee or the Servicer (including the
costs and expenses of conducting the auction described in Section 9.01(a)) and
any unreimbursed Servicing Fees, Advances or Servicing Advances, (d) all
interest accrued on, as well as amounts necessary to retire, the principal
balance of the NIM Notes, (e) any costs and damages incurred by the Issuing
Entity (or the Trustee on behalf of the Issuing Entity) in connection with any
violation by the affected Mortgage Loan of any anti-predatory or anti-abusive
lending laws and (f) any Swap Termination Payment, other than a Defaulted Swap
Termination Payment, owed to the Swap Counterparty; such Swap Termination
Payment shall include any payment resulting from the termination of the Swap
Agreement after the Clean Up Call Date but prior to the final distribution to
the Certificates.

     Closing Date: March 26, 2007.

     Code: The Internal Revenue Code of 1986, including any successor or
amendatory provisions.

     Collection Account: The separate Eligible Accounts created and initially
maintained by the Servicer pursuant to Section 3.05(d) in the name of the
Trustee for the benefit of the Certificateholders and designated "Wilshire
Credit Corporation, in trust for registered holders of Specialty Underwriting
and Residential Finance Trust, Mortgage Loan Asset-Backed Certificates, Series
2007-AB1". Funds in the Collection Account shall be held in trust for the
Certificateholders for the uses and purposes set forth in this Agreement.

     Combined Loan-to-Value Ratio: For any Mortgage Loan in a second lien
position, the fraction, expressed as a percentage, the numerator of which is the
sum of (1) the original principal balance of the related Mortgage Loan and (2)
any outstanding principal balances of Mortgage Loans the liens on which are
senior to the lien on such related Mortgage Loan (such sum calculated at the
date of origination of such related Mortgage Loan) and the denominator of which
is the lesser of (A) the Appraised Value of the related Mortgaged Property and
(B) the sales price of the related Mortgaged Property at time of origination.

     Commission: The Securities and Exchange Commission.

     Compensating Interest: For any Distribution Date and all Principal
Prepayments in full in respect of a Mortgage Loan that are received during the
period from the first day of the related Prepayment Period through the last day
of the calendar month preceding such Distribution Date, a payment made by the
Servicer in an amount not to exceed the product of (a) one-twelfth of 0.25% and
(b) the aggregate Stated Principal Balance of the Mortgage Loans for such
Distribution Date, equal to the amount of interest at the Net Mortgage Rate for
that Mortgage Loan from the date of prepayment through the last day of such
preceding calendar month.


                                       35

<PAGE>

     Condemnation Proceeds: All awards or settlements in respect of a Mortgaged
Property, whether permanent or temporary, partial or entire, by exercise of the
power of eminent domain or condemnation, to the extent not required to be
released either to a Mortgagor in accordance with the terms of the related
mortgage loan documents or to the holder of a senior lien on the Mortgaged
Property.

     Corresponding Certificates: With respect to the Class LTA-1 Interest, the
Class A-1 and Class R Certificates. With respect to the Class LTA-2A Interest,
the Class A-2A Certificates. With respect to the Class LTA-2B Interest, the
Class A-2B Certificates. With respect to the Class LTA-2C Interest, the Class
A-2C Certificates. With respect to the Class LTA-2D Interest, the Class A-2D
Certificates. With respect to the Class LTM-1 Interest, the Class M-1
Certificates. With respect to the Class LTM-2 Interest, the Class M-2
Certificates. With respect to the Class LTM-3 Interest, the Class M-3
Certificates. With respect to the Class LTM-4 Interest, the Class M-4
Certificates. With respect to the Class LTM-5 Interest, the Class M-5
Certificates. With respect to the Class LTM-6 Interest, the Class M-6
Certificates. With respect to the Class LTB-1 Interest, the Class B-1
Certificates. With respect to the Class LTB-2 Interest, the Class B-2
Certificates. With respect to the Class LTB-3 Interest, the Class B-3
Certificates.

     Corresponding REMIC Regular Interest: For each Class of Certificates, the
interest in the Upper Tier REMIC listed on the same row in the table entitled
"Upper Tier REMIC" in the Preliminary Statement.

     Corridor Contract: Any of the Class A-1 Corridor Contract, the Class A-2
Corridor Contract or the Subordinate Certificate Corridor Contract.

     Corridor Contract Account: The separate Eligible Account created and
maintained by the Trustee pursuant to Section 4.04(j) in the name of the Trustee
for the benefit of the Issuing Entity and designated "U.S. Bank National
Association, as trustee, in trust for registered holders of Specialty
Underwriting and Residential Finance Trust, Mortgage Loan Asset-Backed
Certificates, Series 2007-AB1." Funds in the Corridor Contract Account shall be
held in trust for the Issuing Entity for the uses and purposes set forth in this
Agreement.

     Corridor Contract Notional Balance: Any of the Class A-1 Corridor Contract
Notional Balance, the Class A-2 Corridor Contract Notional Balance or the
Subordinate Certificate Corridor Contract Notional Balance.

     Corridor Contract Termination Date: Any of the Class A-1 Corridor Contract
Termination Date, the Class A-2 Corridor Contract Termination Date or the
Subordinate Certificate Corridor Contract Termination Date.

     Corridor Posted Collateral Account: The segregated Eligible Account that
may be created and maintained by the Trustee pursuant to Section 4.04(j)(iv) in
the name of the Trustee for the benefit of the Issuing Entity and designated
"U.S. Bank National Association, as trustee, in trust for registered holders of
Specialty Underwriting and Residential Finance Trust, Mortgage Loan Asset-Backed
Certificates, Series 2007-AB1." Funds in the Corridor Posted Collateral Account
shall be held in trust for the Issuing Entity for the uses and purposes set
forth in the Corridor Contracts.

     Current Interest: Any of the Class A-1 Current Interest, the Class A-2A
Current Interest, the Class A-2B Current Interest, the Class A-2C Current
Interest, the Class A-2D Current Interest, the Class R Current Interest, the
Class M-1 Current Interest, the Class M-2 Current Interest, the Class M-3
Current Interest, the Class M-4 Current Interest, the Class M-5 Current
Interest, the Class M-6 Current Interest, the Class B-1 Current Interest, the
Class B-2 Current Interest, the Class B-3 Current Interest and the Class C
Current Interest.


                                       36

<PAGE>

     Cut-off Date: March 1, 2007.

     Cut-off Date Principal Balance: As to any Mortgage Loan, the unpaid
principal balance thereof as of the close of business on the calendar day
immediately preceding the Cut-off Date after application of all payments of
principal due on or prior to the Cut-off Date, whether or not received, and all
Principal Prepayments received prior to the Cut-off Date, but without giving
effect to any installments of principal received in respect of Due Dates after
the Cut-off Date.

     Defaulted Swap Termination Payment: Any payment required to be made by the
Supplemental Interest Trust to the Swap Counterparty pursuant to the Swap
Agreement as a result of an event of default under the Swap Agreement with
respect to which the Swap Counterparty is the defaulting party or a termination
event (including a Downgrade Termination Event) under that agreement (other than
illegality or a tax event) with respect to which the Swap Counterparty is the
sole Affected Party (as defined in the Swap Agreement).

     Definitive Certificates: As defined in Section 5.06.

     Deleted Mortgage Loan: A Mortgage Loan replaced or to be replaced by a
Replacement Mortgage Loan.

     Delinquent: A Mortgage Loan is "delinquent" if any payment due thereon is
not made pursuant to the terms of such Mortgage Loan by the close of business on
the day such payment is scheduled to be due. A Mortgage Loan is "30 days
delinquent" if such payment has not been received by the close of business on
the corresponding day of the month immediately succeeding the month in which
such payment was due, or, if there is no such corresponding day (e.g., as when a
30-day month follows a 31-day month in which a payment was due on the 31st day
of such month), then on the last day of such immediately succeeding month.
Similarly for "60 days delinquent," "90 days delinquent" and so on.

     Denomination: With respect to each Certificate, the amount set forth on the
face thereof as the "Initial Principal Balance of this Certificate."

     Depositor: Merrill Lynch Mortgage Investors, Inc., a Delaware corporation,
or any successor in interest.

     Depository: The initial Depository shall be The Depository Trust Company
("DTC"), the nominee of which is Cede & Co., or any other organization
registered as a "clearing agency" pursuant to Section 17A of the Securities
Exchange Act of 1934, as amended. The Depository shall initially be the
registered Holder of the Book-Entry Certificates. The Depository shall at all
times be a "clearing corporation" as defined in Section 8-102(3) of the Uniform
Commercial Code of the State of New York.

     Depository Agreement: With respect to Classes of Book-Entry Certificates,
the agreement between the Trustee and the initial Depository.

     Depository Participant: A broker, dealer, bank or other financial
institution or other Person for whom from time to time a Depository effects
book-entry transfers and pledges of securities deposited with the Depository.

     Designated Transaction: A transaction in which the assets underlying the
Certificates consist of single-family residential, multi-family residential,
home equity, manufactured housing and/or commercial mortgage obligations that
are secured by single family residential, multi-family residential, commercial
real property or leasehold interests therein.


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<PAGE>

     Determination Date: With respect to any Distribution Date, the 15th day of
the month of such Distribution Date or, if such 15th day is not a Business Day,
the immediately preceding Business Day.

     Disqualified Organization: (1) the United States, any state or political
subdivision thereof, any foreign government, any international organization, or
any agency or instrumentality of any of the foregoing, (2) any organization
(other than a cooperative described in Section 521 of the Code) which is exempt
from tax under Chapter 1 of Subtitle A of the Code unless such organization is
subject to the tax imposed by Section 511 of the Code and (3) any organization
described in Section 1381(a)(2)(C) of the Code.

     Distribution Date: The 25th day of each calendar month after the initial
issuance of the Certificates, or if such 25th day is not a Business Day, the
next succeeding Business Day, commencing in April 2007.

     Downgrade Termination Event: An event whereby (x) the Swap Counterparty (or
its guarantor) ceases to have short term unsecured and/or long term debt ratings
at least equal to the levels specified in the Swap Agreement, and (y) at least
one of the following events has not occurred (except to the extent otherwise
approved by the Rating Agencies): (i) the Swap Counterparty fails to post
collateral securing its obligations under the Swap Agreement, (ii) the Swap
Counterparty fails to post collateral securing its obligations under the Swap
Agreement and/or fails to obtain a guarantor or a substitute swap counterparty
acceptable to the Supplemental Interest Trust Trustee and the Rating Agencies
(if required under the Swap Agreement) that will assume the obligations of the
Swap Counterparty under the Swap Agreement or (iii) the Swap Counterparty is
defaulting on certain obligations required as a result of the ratings downgrade
and the Supplemental Interest Trust Trustee obtains a guarantor or secures a
substitute swap counterparty acceptable to the Rating Agencies (if required
under the Swap Agreement) that will assume the obligations of the Swap
Counterparty under the Swap Agreement.

     Due Date: With respect to any Distribution Date and any Mortgage Loan, the
day during the related Due Period on which a Scheduled Payment is due.

     Due Period: With respect to any Distribution Date, the period beginning on
the second day of the calendar month preceding the calendar month in which such
Distribution Date occurs and ending on the first day of the month in which such
Distribution Date occurs.

     Eligible Account: An account that is (i) maintained with a depository
institution the long-term unsecured debt obligations of which are rated by each
Rating Agency in one of its two highest rating categories, or (ii) maintained
with the corporate trust department of a bank which (A) has a rating of at least
Baa3 or P-3 by Moody's and (B) is either the Depositor or the corporate trust
department of a national banking association or banking corporation which has a
rating of at least A-1 by S&P or F1 by Fitch, or (iii) an account or accounts
the deposits in which are fully insured by the FDIC, or (iv) an account or
accounts, acceptable to each Rating Agency without reduction or withdrawal of
the rating of any Class of Certificates, as evidenced in writing, by a
depository institution in which such accounts are insured by the FDIC (to the
limit established by the FDIC), the uninsured deposits in which accounts are
otherwise secured such that, as evidenced by an Opinion of Counsel delivered to
and acceptable to the Trustee and each Rating Agency, the Certificateholders
have a claim with respect to the funds in such account and a perfected first
security interest against any collateral (which shall be limited to Permitted
Investments) securing such funds that is superior to claims of any other
depositors or creditors of the depository institution with which such account is
maintained, or (v) maintained at an eligible institution whose commercial paper,
short-term debt or other short-term deposits are rated at least A-1+ by S&P and
F-1+ by Fitch, or (vi) maintained with a federal or state chartered depository
institution the deposits in which are insured by the FDIC to the applicable
limits and the short-term unsecured debt obligations of


                                       38

<PAGE>

which (or, in the case of a depository institution that is a subsidiary of a
holding company, the short-term unsecured debt obligations of such holding
company) are rated A-1 by S&P or Prime-1 by Moody's at the time any deposits are
held on deposit therein, or (vii) a segregated trust account or accounts
maintained with a federal or state chartered depository institution or trust
company acting in its fiduciary capacity, or (viii) otherwise acceptable to each
Rating Agency, as evidenced by a letter from each Rating Agency to the Trustee.

     ERISA: The Employee Retirement Income Security Act of 1974, including any
successor or amendatory provisions.

     ERISA-Qualifying Underwriting: A best efforts or firm commitment
underwriting or private placement that would satisfy the requirements of
Prohibited Transaction Exemption 90-29, Exemption Application No. D-8012, 55
Fed. Reg. 21459 (1990), as amended, granted to the Underwriter by the United
States Department of Labor (or any other applicable underwriter's exemption
granted by the United States Department of Labor), except, in relevant part, for
the requirement that the certificates have received a rating at the time of
acquisition that is in one of the three (or four, in the case of a "designated
transaction") highest generic rating categories by at least one of the Rating
Agencies.

     ERISA Restricted Certificates: The Class C and Class P Certificates and any
other Certificate, as long as the acquisition and holding of such other
Certificate is not covered by and exempt under any applicable underwriter's
exemption granted by the United States Department of Labor.

     Escrow Account: As defined in Section 3.06 hereof.

     Event of Default: As defined in Section 7.01 hereof.

     Exception Report: As defined in Section 2.02 hereof.

     Excess Interest: On any Distribution Date, for any Class of the Class A
Certificates, Class R Certificate, Class M Certificates and Class B
Certificates, the excess, if any, of (1) the amount of interest such Class of
Certificates is entitled to receive on such Distribution Date over (2) the
amount of interest such Class of Certificates would have been entitled to
receive on such Distribution Date at an interest rate equal to the REMIC
Pass-Through Rate.

     Excess Proceeds: With respect to any Liquidated Loan, any Liquidation
Proceeds that are in excess of the sum of (1) the unpaid principal balance of
such Liquidated Loan as of the date of such liquidation plus (2) interest at the
Mortgage Rate from the Due Date as to which interest was last paid or advanced
to Certificateholders (and not reimbursed to the Servicer) up to the Due Date in
the month in which such Liquidation Proceeds are required to be distributed on
the unpaid principal balance of such Liquidated Loan outstanding during each Due
Period as to which such interest was not paid or advanced.

     Exchange Act: The Securities Exchange Act of 1934, as amended.

     Existing Servicing Agreement: The Servicing Agreement between Merrill Lynch
Mortgage Lending, Inc., as Owner, and Wilshire Credit Corporation, as Servicer,
dated as of January 1, 2005, as at any time amended and in effect.

     Extra Principal Distribution Amount: With respect to any Distribution Date,
(1) prior to the Stepdown Date, the excess of (A) the sum of (i) the Aggregate
Certificate Principal Balance immediately preceding such Distribution Date
reduced by the Principal Funds with respect to such Distribution Date and (ii)
$6,300,000 over (B) the Pool Stated Principal Balance of the Mortgage Loans as
of such


                                        39

<PAGE>

Distribution Date and (2) on and after the Stepdown Date, the excess, if any, of
(A) the sum of (i) the Aggregate Certificate Principal Balance immediately
preceding such Distribution Date, reduced by the Principal Funds with respect to
such Distribution Date and (ii) the greater of (a) 3.60% of the Pool Stated
Principal Balance of the Mortgage Loans and (b) the Minimum Required
Overcollateralization Amount less (B) the Pool Stated Principal Balance of the
Mortgage Loans as of such Distribution Date; provided, however, that if on any
Distribution Date a Stepdown Trigger Event is in effect, the Extra Principal
Distribution Amount will not be reduced to the applicable percentage of the
then-current Stated Principal Balance of the Mortgage Loans (and will remain
fixed at the applicable percentage of the Stated Principal Balance of the
Mortgage Loans as of the Due Date immediately prior to the Stepdown Trigger
Event) until the next Distribution Date on which the Stepdown Trigger Event is
not in effect.

     Fannie Mae: A federally chartered and privately owned corporation organized
and existing under the Federal National Mortgage Association Charter Act, or any
successor thereto.

     FDIC: The Federal Deposit Insurance Corporation, or any successor thereto.

     Fitch: Fitch, Inc., or its successor in interest.

     Fixed Rate Mortgage Loan: A Mortgage Loan identified in the Mortgage Loan
Schedule as having a Mortgage Rate which is fixed.

     Floating Rate Certificate Carryover: With respect to a Distribution Date,
in the event that the Pass-Through Rate for a Class of Class A, Class R, Class M
or Class B Certificates is based upon the related Available Funds Cap or the
related Maximum Rate Cap, the sum of (A) the excess of (1) the amount of
interest that such Class would have been entitled to receive on such
Distribution Date had the Pass-Through Rate for that Class not been calculated
based on the related Available Funds Cap or the related Maximum Rate Cap, up to
but not exceeding the greater of (a) the related Maximum Rate Cap or (b) the sum
of (i) the related Available Funds Cap and (ii) the product of (AA) a fraction,
the numerator of which is 360 and the denominator of which is the actual number
of days in the related Accrual Period and (BB) the sum of (x) the quotient of
(I) an amount equal to the proceeds, if any, payable under the related Corridor
Contract and (II) the aggregate Certificate Principal Balance of each Class of
Certificates to which such Corridor Contract relates for such Distribution Date
and (y) the quotient obtained by dividing (I) an amount equal to any Net Swap
Payments owed by the Swap Counterparty for such Distribution Date by (II) the
aggregate Stated Principal Balance of the Mortgage Loans as of the immediately
preceding Distribution Date over (2) the amount of interest such Class was
entitled to receive on such Distribution Date based on the applicable Available
Funds Cap; (B) the unpaid portion of any such excess from prior Distribution
Dates (and interest accrued thereon at the then applicable Pass-Through Rate,
without giving effect to the related Available Funds Cap) and (C) any amount
previously distributed with respect to Floating Rate Certificate Carryover for
such Class that is recovered as a voidable preference by a trustee in
bankruptcy.

     Freddie Mac: A corporate instrumentality of the United States created and
existing under Title III of the Emergency Home Finance Act of 1970, as amended,
or any successor thereto.

     Grantor Trusts: The grantor trusts described in Section 2.07 hereof.

     Gross Margin: The percentage set forth in the related Mortgage Note for
each of the Adjustable Rate Mortgage Loans which is to be added to the
applicable index for use in determining the Mortgage Rate on each Adjustment
Date, and which is set forth in the Mortgage Loan Schedule for each Adjustable
Rate Mortgage Loan.


                                       40

<PAGE>

     Group One: The portion of the Mortgage Pool identified as "Group One" in
the Prospectus Supplement.

     Group One Mortgage Loan: Any Mortgage Loan at any time identified as a
Mortgage Loan in Group One in the Mortgage Loan Schedule.

     Group One Net WAC: The Net WAC of Group One.

     Group One Principal Distribution Amount: As of any Distribution Date, the
amount equal to the lesser of (i) the aggregate Certificate Principal Balance of
the Class A-1 and Class R Certificates and (ii) the product of (x) the Group One
Principal Distribution Percentage and (y) the Class A Principal Distribution
Amount; provided, however, that (A) with respect to any Distribution Date on
which the Class A-1 and Class R Certificates are outstanding and the Certificate
Principal Balance of the Class A-2 Certificates has been reduced to zero, the
Group Two Principal Distribution Amount in excess of the amount necessary to
reduce the Certificate Principal Balance of the Class A-2 Certificates to zero
will be applied to increase the Group One Principal Distribution Amount and (B)
with respect to any Distribution Date thereafter, the Group One Principal
Distribution Amount will equal the Class A Principal Distribution Amount.

     Group One Principal Distribution Percentage: With respect to any
Distribution Date, a fraction expressed as a percentage, the numerator of which
is the amount of Principal Funds received with respect to Mortgage Loans in
Group One and the denominator of which is the amount of Principal Funds received
from all of the Mortgage Loans in the mortgage pool.

     Group Two: The portion of the Mortgage Pool identified as "Group Two" in
the Prospectus Supplement.

     Group Two Mortgage Loan: Any Mortgage Loan at any time identified as a
Mortgage Loan in Group Two in the Mortgage Loan Schedule.

     Group Two Net WAC: The Net WAC of Group Two.

     Group Two Principal Distribution Amount: As of any Distribution Date, the
amount equal to the lesser of (i) the aggregate Certificate Principal Balance of
the Class A-2 Certificates and (ii) the product of (x) the Group Two Principal
Distribution Percentage and (y) the Class A Principal Distribution Amount;
provided, however, that (A) with respect to any Distribution Date on which the
Class A-2 Certificates are outstanding and the Certificate Principal Balances of
the Class A-1 and Class R Certificates have been reduced to zero, the Group One
Principal Distribution Amount in excess of the amount necessary to reduce the
Certificate Principal Balance of the Class A-1 Certificates and Class R
Certificate to zero will be applied to increase the Group Two Principal
Distribution Amount and (B) with respect to any Distribution Date thereafter,
the Group Two Principal Distribution Amount will equal the Class A Principal
Distribution Amount.

     Group Two Principal Distribution Percentage: With respect to any
Distribution Date, a fraction expressed as a percentage, the numerator of which
is the amount of Principal Funds received with respect to Mortgage Loans in
Group Two and the denominator of which is the amount of Principal Funds received
from all of the Mortgage Loans in the mortgage pool.

     Indenture: An indenture relating to the issuance of NIM Notes.


                                       41

<PAGE>

     Initial Adjustment Date: As to any Adjustable Rate Mortgage Loan, the first
Adjustment Date following the origination of such Mortgage Loan.

     Initial Certificate Principal Balance: With respect to any Certificate
(other than the Class P Certificates), the Certificate Principal Balance of such
Certificate or any predecessor Certificate on the Closing Date as set forth in
Section 5.01 hereof.

     Initial Mortgage Rate: As to each Mortgage Loan, the Mortgage Rate in
effect prior to the Initial Adjustment Date.

     Insurance Policy: With respect to any Mortgage Loan included in the Trust
Fund, any insurance policy, including all riders and endorsements thereto in
effect with respect to such Mortgage Loan, including any replacement policy or
policies for any insurance policies.

     Insurance Proceeds: Proceeds paid in respect of the Mortgage Loans pursuant
to any Insurance Policy or any other insurance policy covering a Mortgage Loan,
to the extent such proceeds are payable to the mortgagee under the Mortgage, the
Servicer or the trustee under the deed of trust and are not applied to the
restoration of the related Mortgaged Property or released to either the
Mortgagor or to the holder of a senior lien on the related Mortgage Property in
accordance with the procedures that the Servicer would follow in servicing
mortgage loans held for its own account, in each case other than any amount
included in such Insurance Proceeds in respect of Insured Expenses.

     Insured Expenses: Expenses covered by an Insurance Policy or any other
insurance policy with respect to the Mortgage Loans.

     Interest Carry Forward Amount: Any of the Class A-1 Interest Carry Forward
Amount, the Class A-2A Interest Carry Forward Amount, the Class A-2B Interest
Carry Forward Amount, the Class A-2C Interest Carry Forward Amount, the Class
A-2D Interest Carry Forward Amount, the Class R Interest Carry Forward Amount,
the Class M-1 Interest Carry Forward Amount, the Class M-2 Interest Carry
Forward Amount, the Class M-3 Interest Carry Forward Amount, the Class M-4
Interest Carry Forward Amount, the Class M-5 Interest Carry Forward Amount, the
Class M-6 Interest Carry Forward Amount, the Class B-1 Interest Carry Forward
Amount, the Class B-2 Interest Carry Forward Amount, the Class B-3 Interest
Carry Forward Amount or the Class C Interest Carry Forward Amount, as the case
may be.

     Interest Determination Date: With respect to the LIBOR Certificates, for
any Accrual Period, the second LIBOR Business Day preceding the commencement of
such Accrual Period.

     Interest Funds: With respect to any Distribution Date, the sum, without
duplication, of (1) all scheduled interest due during the related Due Period and
received before the related Servicer Remittance Date or advanced on or before
the related Servicer Remittance Date less the Servicing Fee, (2) all Advances
relating to interest with respect to the Mortgage Loans, (3) all Compensating
Interest with respect to the Mortgage Loans, (4) Liquidation Proceeds with
respect to the Mortgage Loans (to the extent such Liquidation Proceeds relate to
interest) collected during the related Prepayment Period, (5) proceeds of any
purchase pursuant to Sections 2.02, 2.03 or 9.01 (to the extent such proceeds
relate to interest) and (6) prepayment charges received with respect to the
Mortgage Loans during the related Prepayment Period less (A) all Non-Recoverable
Advances relating to interest and (B) other amounts reimbursable to the Servicer
and the Trustee pursuant to this Agreement and allocable to interest.

     Issuing Entity: Specialty Underwriting and Residential Finance Trust,
Series 2007-AB1.


                                        42

<PAGE>

     Last Scheduled Distribution Date: With respect to any Class of
Certificates, the Distribution Date in March 2037.

     Latest Possible Maturity Date: The first Distribution Date following the
third anniversary of the scheduled maturity date of the Mortgage Loan in the
Trust Fund having the latest scheduled maturity date as of the Cut-off Date.

     Lender: As defined in Section 10.14(a).

     LIBOR Business Day: Any day on which banks in the City of London, England
and New York City, U.S.A. are open and conducting transactions in foreign
currency and exchange.

     LIBOR Certificates: The Class A, Class M, Class B and Class R Certificates.

     Liquidated Loan: With respect to any Distribution Date, a defaulted
Mortgage Loan that either (a) pursuant to Section 3.12 has been realized upon or
liquidated through deed-in-lieu of foreclosure, foreclosure sale, trustee's sale
or other realization as provided by applicable law governing the real property
subject to the related Mortgage and any security agreements and as to which the
Servicer has certified (in accordance with Section 3.12) in the related
Prepayment Period that it has received all amounts it expects to receive in
connection with such liquidation or (b) as to which is not a first lien Mortgage
Loan and is delinquent 180 days or longer, the Servicer has certified in a
certificate of an officer of the Servicer delivered to the Depositor and the
Trustee that it does not believe that there is a reasonable likelihood that any
further net proceeds will be received or recovered with respect to such Mortgage
Loan.

     Liquidation Proceeds: Amounts, including Insurance Proceeds, received in
connection with the partial or complete liquidation of Mortgage Loans, whether
through trustee's sale, foreclosure sale, sale by the Servicer pursuant to this
Agreement or otherwise or amounts received in connection with any condemnation
or partial release of a Mortgaged Property and any other proceeds received in
connection with an REO Property, less the sum of related unreimbursed Advances,
Servicing Fees, Servicing Advances and any other expenses related to such
Mortgage Loan.

     Loan-to-Value Ratio: With respect to any Mortgage Loan, the fraction,
expressed as a percentage, the numerator of which is the original principal
balance of the related Mortgage Loan and the denominator of which is the lesser
of (x) the Appraised Value of the related Mortgaged Property and (y) the sales
price of the related Mortgaged Property at the time of origination.

     Losses: Any losses, claims, damages, liabilities or expenses collectively.

     Lower Tier REMIC: As described in the Preliminary Statement and Section
2.07.

     Lower Tier REMIC I Marker Interests: Each of the classes of Lower Tier
REMIC Regular Interests other than the Class LTIX Interest, the Class LTIIX
Interest, the Class LTII1A Interest, the Class LTII1B Interest, the Class LTII2A
Interest, the Class LTII2B Interest and the Class LT-IO Interest.

     Lower Tier REMIC II Marker Interests: Each of the Class LTII1A Interest,
the Class LTII1B Interest, the Class LTII2A Interest and the Class LTII2B
Interest.

     Lower Tier REMIC Interests: Each of the Class LTA-1 Interest, the Class
LTA-2A Interest, the Class LTA-2B Interest, the Class LTA-2C Interest, the Class
LTA-2D Interest, the Class LTM-1 Interest, the Class LTM-2 Interest, the Class
LTM-3 Interest, the Class LTM-4 Interest, the Class LTM-5 Interest,


                                       43

<PAGE>

the Class LTM-6 Interest, the Class LTB-1 Interest, the Class LTB-2 Interest,
the Class LTB-3 Interest, the Class LTII1A Interest, the Class LTII1B Interest,
the Class LTII2A Interest, the Class LTII2B Interest, the Class LTIX Interest,
the Class LTIIX Interest, the Class LT-IO Interest and the Class LTR Interest.

     Lower Tier REMIC Regular Interests: Each of the Lower Tier REMIC Interests
other than the Class LTR Interest.

     Lower Tier REMIC Subordinate Balance Ratio: The ratio of (i) the principal
balance of the Class LTII1A Interest to (ii) the principal balance of the Class
LTII2A Interest that is equal to the ratio of (i) the excess of (A) the
aggregate Stated Principal Balance of Group One over (B) the current Certificate
Principal Balance of the Class A-1 and Class R Certificates to (ii) the excess
of (A) the aggregate Stated Principal Balance of Group Two over (B) the current
Certificate Principal Balance of the Class A-2 Certificates.

     Maximum Mortgage Rate: With respect to each Adjustable Rate Mortgage Loan,
the maximum rate of interest set forth as such in the related Mortgage Note and
with respect to each Fixed Rate Mortgage Loan, the rate of interest set forth in
the related Mortgage Note.

     Maximum Rate Cap: Any of the Class A-1 Maximum Rate Cap, the Class A-2
Maximum Rate Cap, or the Subordinate Certificate Maximum Rate Cap.

     MERS: Mortgage Electronic Registration Systems, Inc., a corporation
organized and existing under the laws of the State of Delaware, or any successor
thereto.

     MERS Loan: Any Mortgage Loan registered with MERS on the MERS System.

     MERS System: The system of recording transfers of mortgage electronically
maintained by MERS.

     MIN: The loan number for any MERS Loan.

     Minimum Mortgage Rate: With respect to each Adjustable Rate Mortgage Loan,
the minimum rate of interest set forth as such in the related Mortgage Note.

     Minimum Required Overcollateralization Amount: An amount equal to the
product of (x) 0.50% and (y) the Stated Principal Balance of the Mortgage Loans
as of the Cut-off Date.

     MOM Loan: Any Mortgage Loan as to which MERS is acting as mortgagee, solely
as nominee for the originator of such Mortgage Loan and its successors and
assigns.

     Monthly Statement: The statement delivered to the Certificateholders
pursuant to Section 4.05.

     Moody's: Moody's Investors Service, Inc. or any successor in interest.

     Mortgage: With respect to a Mortgage Loan, the mortgage, deed of trust or
other instrument creating a first or second lien or a first or second priority
ownership interest in an estate in fee simple in real property securing a
Mortgage Note.


                                       44

<PAGE>

     Mortgage File: The mortgage documents listed in Section 2.01 hereof
pertaining to a particular Mortgage Loan and any additional documents delivered
to the Trustee to be added to the Mortgage File pursuant to this Agreement.

     Mortgage Group: Either of Group One or Group Two.

     Mortgage Loan Schedule: The list of Mortgage Loans (as from time to time
amended by the Sponsor to reflect the deletion of Deleted Mortgage Loans and the
addition of Replacement Mortgage Loans pursuant to the provisions of this
Agreement) transferred to the Trustee as part of the Trust Fund and from time to
time subject to this Agreement, attached hereto as Exhibit B, setting forth the
following information with respect to each Mortgage Loan:

     (i)   the loan number;

     (ii) the unpaid principal balance of the Mortgage Loans;

     (iii) the Initial Mortgage Rate;

     (iv) the maturity date and the months remaining before maturity date;

     (v)   the original principal balance;

     (vi) the Cut-off Date Principal Balance;

     (vii) the first payment date of the Mortgage Loan;

     (viii) the Loan-to-Value Ratio at origination with respect to a first lien
          Mortgage Loan or the Combined Loan-to-Value Ratio with respect to a
          second lien Mortgage Loan;

     (ix) a code indicating whether the residential dwelling at the time of
          origination was represented to be owner-occupied;

     (x)   a code indicating the property type;

     (xi) with respect to each Adjustable Rate Mortgage Loan:

          (a)   the frequency of each Adjustment Date;

          (b)   the next Adjustment Date;

          (c)   the Maximum Mortgage Rate;

          (d)   the Minimum Mortgage Rate;

          (e)   the Mortgage Rate as of the Cut-off Date;

          (f)   the related Periodic Rate Cap;

          (g)   the Gross Margin; and

           (h)   the lifetime rate cap;


                                       45

<PAGE>

     (xii) the location of the related Mortgaged Property;

     (xiii) a code indicating whether a prepayment charge is applicable;

          (a)   the period during which such prepayment charge is in effect;

          (b)   the amount of such prepayment charge;

          (c)   any limitations or other conditions on the enforceability of such
               prepayment charge; and

          (d)   any other information pertaining to the prepayment charge
               specified in the related Mortgage Note;

     (xiv) the Credit Score and date obtained; and

     (xv) the MIN.

     Mortgage Loans: Such of the mortgage loans transferred and assigned to the
Trustee pursuant to the provisions hereof as from time to time are held as a
part of the Trust Fund (including any REO Property), the mortgage loans so held
being identified in the Mortgage Loan Schedule, notwithstanding foreclosure or
other acquisition of title of the related Mortgaged Property. Any mortgage loan
that was intended by the parties hereto to be transferred to the Trust Fund as
indicated by such Mortgage Loan Schedule which is in fact not so transferred for
any reason shall continue to be a Mortgage Loan hereunder until the Purchase
Price with respect thereto has been paid to the Trust Fund.

     Mortgage Note: The original executed note or other evidence of indebtedness
evidencing the indebtedness of a Mortgagor under a Mortgage Loan and all
amendments, modifications and attachments thereto.

     Mortgage Pool: The aggregate of the Mortgage Loans identified in the
Mortgage Loan Schedule.

     Mortgage Rate: The annual rate of interest borne by a Mortgage Note from
time to time.

     Mortgaged Property: The underlying property securing a Mortgage Loan.

     Mortgagor: The obligor on a Mortgage Note.

     Net Mortgage Rate: As to each Mortgage Loan, and at any time, the per annum
rate equal to the then current Mortgage Rate less the Servicing Fee Rate.

      Net Rate: The per annum rate set forth in footnote 8 to the description of
the Lower Tier REMIC in the Preliminary Statement hereto (such rate being based
on the weighted average of the interest rates on the SWAP REMIC Regular
Interests as adjusted and as set forth in such footnote).

     Net Swap Payment: With respect to any Distribution Date, any net payment
(other than a Swap Termination Payment or Defaulted Swap Termination Payment)
made by the Supplemental Interest Trust to the Swap Counterparty on the related
Fixed Rate Payer Payment Date (as defined in the Swap Agreement) or made by the
Swap Counterparty to the Supplemental Interest Trust on the related Floating
Rate Payer Payment Date (as defined in the Swap Agreement). In each case, the
Net Swap Payment shall not be less than zero.


                                       46

<PAGE>

     Net WAC: With respect to any Distribution Date and for any Mortgage Group,
the weighted average Net Mortgage Rate for the Mortgage Loans in such Mortgage
Group calculated based on the respective Net Mortgage Rates and the Stated
Principal Balances of such Mortgage Loans as of the preceding Distribution Date
(or, in the case of the first Distribution Date, as of the Cut-off Date).

     NIM Notes: Any net interest margin or excess cashflow securities to be
issued pursuant to an Indenture.

     Non-Recoverable Advance: Any portion of an Advance previously made or
proposed to be made by the Servicer that, in the good faith judgment of the
Servicer, will not or, in the case of a current delinquency, would not, be
ultimately recoverable by the Servicer from the related Mortgagor, related
Liquidation Proceeds or otherwise with respect to the related Mortgage Loan.

     Non-Recoverable Servicing Advance: Any portion of a Servicing Advance
previously made or proposed to be made by the Servicer that, in the good faith
judgment of the Servicer, will not or, in the case of a current Servicing
Advance, would not, be ultimately recoverable by the Servicer from the related
Mortgagor, related Liquidation Proceeds or otherwise with respect to the related
Mortgage Loan.

     Non-Supported Interest Shortfall: As defined in Section 4.02.

     Offered Certificates: The Class A Certificates, Class M Certificates, Class
B Certificates and Class R Certificate.

     Officer's Certificate: A certificate (1) signed by the Chairman of the
Board, the Vice Chairman of the Board, the President, a vice president (however
denominated), an Assistant Vice President, the Treasurer, the Secretary, or one
of the assistant treasurers or assistant secretaries of the Depositor, the
Servicer or the Trustee (or any other officer customarily performing functions
similar to those performed by any of the above designated officers and also to
whom, with respect to a particular matter, such matter is referred because of
such officer's knowledge of and familiarity with a particular subject) or (2),
if provided for in this Agreement, signed by a Servicing Officer, as the case
may be, and delivered to the Depositor, the Servicer or the Trustee, as the case
may be, as required by this Agreement.

     One-Month LIBOR: With respect to any Accrual Period, the rate determined by
the Trustee on the related Interest Determination Date on the basis of (a) the
offered rates for one-month United States dollar deposits, as such rates appear
on Telerate page 3750, as of 11:00 a.m. (London time) on such Interest
Determination Date or (b) if such rate does not appear on Telerate Page 3750 as
of 11:00 a.m. (London time), the offered rates of the Reference Banks for
one-month United States dollar deposits, as such rates appear on the Reuters
Screen LIBO Page, as of 11:00 a.m. (London time) on such Interest Determination
Date. If One-Month LIBOR is determined pursuant to clause (b) above, on each
Interest Determination Date, One-Month LIBOR for the related Accrual Period will
be established by the Trustee as follows:

               (i)   If on such Interest Determination Date two or more Reference
                    Banks provide such offered quotations, One-Month LIBOR for
                    the related Accrual Period shall be the arithmetic mean of
                    such offered quotations (rounded upwards if necessary to the
                    nearest whole multiple of 0.03125%).

               (ii) If on such Interest Determination Date fewer than two
                    Reference Banks provide such offered quotations, One-Month
                    LIBOR for the related Accrual Period shall be the higher of
                     (i) One-Month LIBOR as determined on the previous Interest
                    Determination Date and (ii) the Reserve Interest Rate.


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<PAGE>

     Notwithstanding the foregoing, this definition of One-Month LIBOR for the
purposes of the Corridor Contracts and Swap Agreement will be determined in
accordance with such agreements.

     Opinion of Counsel: A written opinion of counsel, who may be counsel for
the Depositor or the Servicer, reasonably acceptable to each addressee of such
opinion; provided, however, that with respect to Section 6.04 or 10.01, or the
interpretation or application of the REMIC Provisions, such counsel must (1) in
fact be independent of the Depositor and the Servicer, (2) not have any direct
financial interest in the Depositor or the Servicer or in any Affiliate of
either, and (3) not be connected with the Depositor or the Servicer as an
officer, employee, promoter, underwriter, trustee, partner, director or person
performing similar functions.

     OTS: The Office of Thrift Supervision.

     Outstanding: With respect to the Certificates as of any date of
determination, all Certificates theretofore executed and authenticated under
this Agreement except: (1) Certificates theretofore canceled by the Trustee or
delivered to the Trustee for cancellation; and (2) Certificates in exchange for
which or in lieu of which other Certificates have been executed by the Trustee
and delivered by the Trustee pursuant to this Agreement.

     Outstanding Mortgage Loan: As of any Distribution Date, a Mortgage Loan
with a Stated Principal Balance greater than zero that was not the subject of a
Principal Prepayment in full, and that did not become a Liquidated Loan, prior
to the end of the related Due Period.

     Overcollateralization Amount: As of any date of determination, the excess
of (1) the Stated Principal Balance of the Mortgage Loans over (2) the
Certificate Principal Balance of the Certificates (other than the Class P
Certificates and the Class C Certificates).

     Overcollateralization Deficiency Amount: As of any date of determination,
if the Overcollateralization Amount is less than the Targeted
Overcollateralization Amount, then the amount equal to the Targeted
Overcollateralization Amount over the Overcollateralization Amount; otherwise,
zero.

     Overcollateralization Release Amount: As of any date of determination, if
the Overcollateralization Amount is greater than the Targeted
Overcollateralization Amount, then the amount equal to the Overcollateralization
Amount over the Targeted Overcollateralization Amount; otherwise, zero.

     Ownership Interest: As to any Certificate, any ownership interest in such
Certificate including any interest in such Certificate as the Holder thereof and
any other interest therein, whether direct or indirect, legal or beneficial.

     Pass-Through Rate: With respect to any Class of Certificates, the
corresponding Pass-Through Rate for such Class of Certificates.

     Percentage Interest: With respect to:

               (i)   any Class, the percentage interest in the undivided
                    beneficial ownership interest evidenced by such Class which
                    shall be equal to the Certificate Principal Balance of such
                    Class divided by the aggregate Certificate Principal Balance
                    of all Classes; and


                                       48

<PAGE>

               (ii) any Certificate, the Percentage Interest evidenced thereby
                    of the related Class shall equal the percentage obtained by
                    dividing the Denomination of such Certificate by the
                    aggregate of the Denominations of all Certificates of such
                    Class; except that in the case of any Class P Certificates,
                    the Percentage Interest with respect to such Certificate
                    shown on the face of such Certificate.

     Periodic Rate Cap: As to each Adjustable Rate Mortgage Loan and the related
Mortgage Note, the provision therein that limits permissible increases and
decreases in the Mortgage Rate on any Adjustment Date.

     Permitted Activities: The primary activities of the Issuing Entity created
pursuant to this Agreement which shall be:

          (i)   holding Mortgage Loans transferred from the Depositor and other
               assets of the Issuing Entity, including the Corridor Contracts
               and the Supplemental Interest Trust subtrust, which in turn holds
               the Swap Agreement, and any credit enhancement and passive
               derivative financial instruments that pertain to beneficial
               interests issued or sold to parties other than the Depositor, its
               Affiliates, or its agents;

          (ii) issuing Certificates and other interests in the assets of the
               Issuing Entity;

          (iii) through the appropriate subtrust, as applicable, receiving
               collections on the Mortgage Loans and the Swap Agreement and
                making payments on such Certificates and interests in accordance
               with the terms of this Agreement; and

          (iv) engaging in other activities that are necessary or incidental to
               accomplish these limited purposes, which activities cannot be
               contrary to the status of the Issuing Entity as a qualified
               special purpose entity under existing accounting literature.

     Permitted Investments: At any time, any one or more of the following
obligations and securities:

          (i)   obligations of the United States or any agency thereof, provided
               such obligations are backed by the full faith and credit of the
               United States;

          (ii) general obligations of or obligations guaranteed by any state of
               the United States or the District of Columbia receiving the
               highest long-term debt rating of each Rating Agency rating the
               Certificates;

          (iii) commercial or finance company paper, other than commercial or
               finance company paper issued by the Depositor, the Trustee or any
               of their Affiliates, which is then receiving the highest
               commercial or finance company paper rating of each such Rating
               Agency;

          (iv) certificates of deposit, demand or time deposits, or bankers'
               acceptances (other than banker's acceptances issued by the
               Trustee or any of its Affiliates) issued by any depository
               institution or trust company incorporated under the laws of the
               United States or of any state thereof and subject to supervision
               and examination by federal and/or state banking authorities,
                provided that the commercial paper and/or long term unsecured
               debt obligations of such depository institution or trust company
               are then rated one of the two highest long-term and the highest
               short-term ratings of each such Rating Agency for such
               securities;


                                       49

<PAGE>

          (v)   demand or time deposits or certificates of deposit issued by any
               bank or trust company or savings institution to the extent that
               such deposits are fully insured by the FDIC;

          (vi) guaranteed reinvestment agreements issued by any bank, insurance
               company or other corporation rated in the two highest long-term
                or the highest short-term ratings of each Rating Agency
               containing, at the time of the issuance of such agreements, such
               terms and conditions as will not result in the downgrading or
               withdrawal of the rating then assigned to the Certificates by any
               such Rating Agency as evidenced by a letter from each Rating
               Agency;

          (vii) repurchase obligations with respect to any security described in
               clauses (i) and (ii) above, in either case entered into with a
               depository institution or trust company (acting as principal)
               described in clause (v) above;

          (viii) securities (other than stripped bonds, stripped coupons or
                instruments sold at a purchase price in excess of 115% of the
               face amount thereof) bearing interest or sold at a discount
               issued by any corporation, other than the Trustee or any of its
               Affiliates, incorporated under the laws of the United States or
               any state thereof which, at the time of such investment, have one
               of the two highest long term ratings of each Rating Agency;

          (ix) interests in any money market fund (including those managed or
               advised by the Trustee or its Affiliates) which at the date of
               acquisition of the interests in such fund and throughout the time
               such interests are held in such fund has the highest applicable
               long term rating by each such Rating Agency; and

          (x)   short term investment funds sponsored by any trust company or
               national banking association incorporated under the laws of the
               United States or any state thereof, including the Trustee or any
               of its Affiliates, which on the date of acquisition has been
               rated by each such Rating Agency in their respective highest
               applicable rating category;

provided, that no such instrument shall be a Permitted Investment if such
instrument (i) evidences the right to receive interest only payments with
respect to the obligations underlying such instrument, (ii) is purchased at a
premium or above par or (iii) is purchased at a deep discount; provided,
further, that no such instrument shall be a Permitted Investment (A) if such
instrument evidences principal and interest payments derived from obligations
underlying such instrument and the interest payments with respect to such
instrument provide a yield to maturity of greater than 120% of the yield to
maturity at par of such underlying obligations, or (B) if it may be redeemed at
a price below the purchase price (the foregoing clause (B) not to apply to
investments in units of money market funds pursuant to clause (ix) above); and
provided, further, (I) that no amount beneficially owned by any REMIC
(including, without limitation, any amounts collected by the Servicer but not
yet deposited in the Collection Account) may be invested in investments (other
than money market funds) treated as equity interests for Federal income tax
purposes, unless the Servicer and/or the Trustee, shall receive an Opinion of
Counsel acceptable to the Servicer and/or the Trustee, at the expense of the
party requesting that such investment be made, to the effect that such
investment will not adversely affect the status of the any REMIC provided for
herein as a REMIC under the Code or result in imposition of a tax on the Issuing
Entity or any REMIC provided for herein and (II) any such investment must be a
"permitted investment" within the meaning of Section 860G(a)(5) of the Code.
Permitted Investments that are subject to prepayment or call may not be
purchased at a price in excess of par. Any Permitted Investment may be held by
or through the Trustee or any of its Affiliates.

     Permitted Transferee: Any Person other than (i) the United States, any
State or political subdivision thereof, or any agency or instrumentality of any
of the foregoing, (ii) a foreign government,


                                       50
<PAGE>

International Organization or any agency or instrumentality of either of the
foregoing, (iii) an organization (except certain farmers' cooperatives described
in Section 521 of the Code) that is exempt from tax imposed by Chapter 1 of the
Code (including the tax imposed by Section 511 of the Code on unrelated business
taxable income) on any excess inclusions (as defined in Section 860E(c)(1) of
the Code) with respect to the Class R Certificate, (iv) rural electric and
telephone cooperatives described in Section 1381(a)(2)(C) of the Code, and (v) a
Person that is not a citizen or resident of the United States, a corporation or
partnership (or other entity treated as a corporation or partnership for United
States federal income tax purposes) created or organized in or under the laws of
the United States or any State thereof or the District of Columbia or an estate
whose income from sources without the United States is includable in gross
income for United States federal income tax purposes regardless of its
connection with the conduct of a trade or business within the United States, or
a trust if a court within the United States is able to exercise primary
supervision over the administration of the trust and one or more United States
persons have authority to control all substantial decisions of the trust,
unless, in the case of this clause (v), such Person has furnished the transferor
and the Trustee with a duly completed Internal Revenue Service Form W-8ECI or
applicable successor form. The terms "United States," "State" and "International
Organization" shall have the meanings set forth in Section 7701 of the Code. A
corporation will not be treated as an instrumentality of the United States or of
any State thereof for these purposes if all of its activities are subject to tax
and, with the exception of the Federal Home Loan Mortgage Corporation, a
majority of its board of directors is not selected by such government unit.

     Person: Any individual, corporation, partnership, limited liability
company, joint venture, association, joint-stock company, trust, unincorporated
organization or government, or any agency or political subdivision thereof.

     Pool Stated Principal Balance: As to any Distribution Date, the aggregate
of the Stated Principal Balances, as of such Distribution Date, of the Mortgage
Loans that were Outstanding Mortgage Loans as of such date.

     Posted Collateral: As defined in the Swap Agreement or the Corridor
Contracts, as applicable.

     Prepayment Assumption: A rate of prepayment, as described in the Prospectus
Supplement in the definition of "Modeling Assumptions," relating to the
Certificates.

     Prepayment Interest Excess: With respect to any Servicer Remittance Date,
for each Mortgage Loan that was the subject of a Principal Prepayment in full
during the portion of the related Prepayment Period occurring between the first
day of the calendar month in which such Servicer Remittance Date occurs and the
last day of the related Prepayment Period, an amount equal to interest (to the
extent received) at the applicable Net Mortgage Rate on the amount of such
Principal Prepayment for the number of days commencing on the first day of the
calendar month in which such Servicer Remittance Date occurs and ending on the
date on which such Principal Prepayment is so applied.

     Prepayment Interest Shortfall: With respect to any Distribution Date, for
each Mortgage Loan that was the subject of a Principal Prepayment in full (other
than a Principal Prepayment in full resulting from the purchase of a Mortgage
Loan pursuant to Section 2.02, 2.03 or 9.01 hereof and other than a Principal
Prepayment in full on a Mortgage Loan received during the period from and
including the first day to and including the 14th day of the month of such
Distribution Date), the amount, if any, by which (i) one month's interest at the
applicable Net Mortgage Rate on the Stated Principal Balance of such Mortgage
Loan as of the preceding Distribution Date exceeds (ii) the amount of interest
paid or collected in connection with such Principal Prepayment.


                                       51

<PAGE>

     Prepayment Period: As to any Distribution Date, for prepayments or
liquidations in full and any prepayment charges associated with such payments in
full, the period from and including the 15th date of the calendar month
preceding the month in which such Distribution Date occurs (or, in the case of
the first Distribution Date, beginning on the Cut-off Date) and including the
14th day of the calendar month in which such Distribution Date occurs and for
partial prepayments or liquidations and any prepayment charges associated with
such partial prepayments, the calendar month preceding the calendar month in
which such Distribution Date occurs.

     Principal Distribution Amount: With respect to each Distribution Date, the
sum of (i) the Principal Funds for such Distribution Date and (ii) any Extra
Principal Distribution Amount for such Distribution Date.

     Principal Funds: With respect to the Mortgage Loans and any Distribution
Date, the sum, without duplication, of (1) the scheduled principal due during
the related Due Period and received before the related Servicer Remittance Date
or required to be advanced by the Servicer on or before the related Servicer
Remittance Date, (2) prepayments of principal in full collected in the related
Prepayment Period, (3) the Stated Principal Balance of each Mortgage Loan that
was purchased by the Depositor or the Servicer during the related Prepayment
Period or, in the case of a purchase pursuant to Section 9.01, on the Business
Day prior to such Distribution Date, (4) the amount, if any, by which the
aggregate unpaid principal balance of any Replacement Mortgage Loan is less than
the aggregate unpaid principal of the related Deleted Mortgage Loans delivered
by the Sponsor in connection with a substitution of a Mortgage Loan pursuant to
Section 2.03(c), (5) all Liquidation Proceeds collected during the related
Prepayment Period (to the extent such Liquidation Proceeds relate to principal
and represent payment in full), (6) Subsequent Recoveries received during the
related Due Period and (7) all other collections and recoveries in respect of
principal during the related Due Period, less (A) all Non-Recoverable Advances
relating to principal with respect to the Mortgage Loans and (B) other amounts
reimbursable to the Servicer and the Trustee pursuant to this Agreement and
allocable to principal.

     Principal Prepayment: Any Mortgagor payment or other recovery of (or
proceeds with respect to) principal on a Mortgage Loan (including Mortgage Loans
purchased or repurchased under Sections 2.02, 2.03 and 9.01 hereof) that is
received in advance of its scheduled Due Date and is not accompanied by an
amount as to interest representing scheduled interest due on any date or dates
in any month or months subsequent to the month of prepayment. Partial Principal
Prepayments shall be applied by the Servicer in accordance with the terms of the
related Mortgage Note.

     Prospectus Supplement: The Prospectus Supplement, dated March 22, 2007,
relating to the public offering of the Offered Certificates.

     PUD: A Planned Unit Development.

     Purchase Price: With respect to any Mortgage Loan required to be
repurchased by the Sponsor pursuant to Section 2.02 or 2.03 hereof, or purchased
by the Servicer pursuant to Section 3.12(c) hereof, an amount equal to the sum
of (i) 100% of the unpaid principal balance of the Mortgage Loan as of the date
of such purchase together with any unreimbursed Servicing Advances, (ii) accrued
interest thereon at the applicable Mortgage Rate from (a) the date through which
interest was last paid by the Mortgagor to (b) the Due Date in the month in
which the Purchase Price is to be distributed to Certificateholders and (iii)
any costs and damages incurred by the Issuing Entity (or the Trustee on behalf
of the Issuing Entity) in connection with any violation by the affected Mortgage
Loan of any anti-predatory or anti-abusive lending laws. With respect to any REO
Property purchased by the Servicer pursuant to Section 3.12(c) hereof, an amount
equal to the fair market value of such REO Property, as determined in good faith
by the Servicer.


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<PAGE>

     Rating Agency: Either of Moody's or S&P. If any such organization or its
successor is no longer in existence, "Rating Agency" shall be a nationally
recognized statistical rating organization, or other comparable Person,
designated by the Depositor, notice of which designation shall be given to the
Trustee. References herein to a given rating category of a Rating Agency shall
mean such rating category without giving effect to any modifiers.

     Rating Agency Condition: As defined in the Swap Agreement.

     Realized Loss: With respect to (1) a Liquidated Loan, the amount, if any,
by which the Stated Principal Balance and accrued interest thereon at the Net
Mortgage Rate exceeds the amount actually recovered by the Servicer with respect
thereto (net of reimbursement of Advances and Servicing Advances) at the time
such Mortgage Loan became a Liquidated Loan or (2) with respect to a Mortgage
Loan which is not a Liquidated Loan, any amount of principal that the Mortgagor
is no longer legally required to pay (except for the extinguishment of debt that
results from the exercise of remedies due to default by the Mortgagor).

     Record Date: With respect to any Distribution Date, the close of business
on the last Business Day of the month preceding the month in which the
applicable Distribution Date occurs (or with respect to the first Distribution
Date, the Closing Date).

     Reference Banks: Barclays Bank PLC, U.S. Bank National Association,
Citibank, N.A., and NatWest, N.A.; provided that if any of the foregoing banks
are not suitable to serve as a Reference Bank, then any leading banks selected
by the Trustee which are engaged in transactions in Eurodollar deposits in the
international Eurocurrency market (i) with an established place of business in
London, England and (ii) whose quotations appear on the Reuters Screen LIBO Page
on the relevant Interest Determination Date.

     Regular Certificate: Any one of the Class A, Class R, Class M and Class B
Certificates.

      Regulation AB: Subpart 229.1100 - Asset Backed Securities (Regulation AB),
17 C.F.R. Sections 229.1100-229.1123, as such may be amended from time to time,
and subject to such clarification and interpretation as have been provided by
the Commission in the adopting release (Asset-Backed Securities, Securities Act
Release No. 33-8518, 70 Fed Reg. 1,506, 1.531 (Jan. 7, 2005)) or by the staff of
the Commission, or as may be provided by the Commission or its staff from time
to time.

     Related Certificates: For each interest in the Upper Tier REMIC, the Class
of Certificates listed on the same row in the table entitled "Upper Tier REMIC"
in the Preliminary Statement.

     Relief Act: The Servicemembers Civil Relief Act or any similar state laws
or regulations.

     REMIC: A "real estate mortgage investment conduit" within the meaning of
section 860D of the Code. References herein to "the REMICs" or "a REMIC" shall
mean any (or, as the context requires, all) of the SWAP REMIC, the Lower Tier
REMIC and the Upper Tier REMIC.

     REMIC Pass-Through Rate: In the case of a Class of the Class A, Class M and
Class B Certificates, the Upper Tier REMIC Net WAC Cap for the Corresponding
REMIC Regular Interest.

     REMIC Provisions: Provisions of the federal income tax law relating to real
estate mortgage investment conduits, which appear at sections 860A through 860G
of Subchapter M of Chapter 1 of the Code, and related provisions, and proposed,
temporary and final regulations and published rulings,


                                        53

<PAGE>

notices and announcements promulgated thereunder, as the foregoing may be in
effect from time to time as well as provisions of applicable state laws.

     REMIC Regular Interests: Each of the interests in the Upper Tier REMIC as
set forth in the Preliminary Statement other than the Residual Interest.

     REMIC SWAP Rate: For each Distribution Date (and the related Accrual
Period), a per annum rate equal to the Fixed Rate under the Swap Agreement for
such Distribution Date, as set forth in the Prospectus Supplement.

     Remittance Report: As defined in Section 4.04(k) hereof.

     REO Property: A Mortgaged Property acquired by the Servicer, on behalf of
the Trustee for the benefit of the Certificateholders, through foreclosure or
deed-in-lieu of foreclosure in connection with a defaulted Mortgage Loan.

     Replacement Mortgage Loan: A Mortgage Loan substituted by the Depositor for
a Deleted Mortgage Loan, which must, on the date of such substitution, as
confirmed in a Request for Release, substantially in the form of Exhibit I (1)
have a Stated Principal Balance (or in the case of a substitution of more than
one Mortgage Loan for a Deleted Mortgage Loan, an aggregate Stated Principal
Balance), after deduction of the principal portion of the Scheduled Payment due
in the month of substitution, not in excess of, and not less than 90% of the
Stated Principal Balance of the Deleted Mortgage Loan; (2) with respect to any
Fixed Rate Mortgage Loan, have a Mortgage Rate not less than or no more than 1%
per annum higher than the Mortgage Rate of the Deleted Mortgage Loan and, with
respect to any Adjustable Rate Mortgage Loan: (A) have a Maximum Mortgage Rate
no more than 1% per annum higher or lower than the Maximum Mortgage Rate of the
Deleted Mortgage Loan; (B) have a Minimum Mortgage Rate no more than 1% per
annum higher or lower than the Minimum Mortgage Rate of the Deleted Mortgage
Loan; (C) have the same index and Periodic Rate Cap as that of the Deleted
Mortgage Loan and a Gross Margin not more than 1% per annum higher or lower than
that of the Deleted Mortgage Loan; (D) not permit conversion of the related
Mortgage Rate to a fixed Mortgage Rate and (F) currently be accruing interest at
a rate not more than 1% per annum higher or lower than that of the Deleted
Mortgage Loan; (3) have a similar or higher FICO score or credit grade than that
of the Deleted Mortgage Loan; (4) have a Loan-to-Value Ratio (or a Combined
Loan-to-Value Ratio, in the case of Mortgage Loans in a second lien position) no
higher than that of the Deleted Mortgage Loan; (5) have a remaining term to
maturity no greater than (and not more than one year less than) that of the
Deleted Mortgage Loan; (6) provide for a prepayment charge on terms
substantially similar to those of the prepayment charge, if any, of the Deleted
Mortgage Loan; (7) have the same lien priority as the Deleted Mortgage Loan; (8)
constitute the same occupancy type as the Deleted Mortgage Loan; and (9) comply
with each representation and warranty set forth in Section 2.03 hereof.

     Request for Release: The Request for Release of Documents submitted by the
Servicer to the Trustee, substantially in the form of Exhibit I hereto.

     Required Insurance Policy: With respect to any Mortgage Loan, any insurance
policy that is required to be maintained from time to time under this Agreement.

     Required Percentage: With respect to any Distribution Date following a
Stepdown Date, the quotient of (1) the excess of (A) the aggregate Stated
Principal Balance of the Mortgage Loans as of such Distribution Date, over (B)
the Certificate Principal Balance of the most senior Class of Certificates
outstanding as of such Distribution Date, prior to giving effect to
distributions to be made on such


                                        54

<PAGE>

Distribution Date and (2) the aggregate Stated Principal Balance of the Mortgage
Loans as of such Distribution Date.

     Requirements: Any rules or regulations promulgated pursuant to the
Sarbanes-Oxley Act of 2002 (as such may be amended from time to time).

     Reserve Interest Rate: With respect to any Interest Determination Date, the
rate per annum that the Trustee determines to be (1) the arithmetic mean
(rounded upwards if necessary to the nearest whole multiple of 0.03125%) of the
one-month United States dollar lending rates which New York City banks selected
by the Trustee are quoting on the relevant Interest Determination Date to the
principal London offices of leading banks in the London interbank market or (2)
in the event that the Trustee can determine no such arithmetic mean, the lowest
one-month United States dollar lending rate which New York City banks selected
by the Trustee are quoting on such Interest Determination Date to leading
European banks.

     Residual Certificate: The Class R Certificate.

     Residual Interest: An interest in the Upper Tier REMIC that is entitled to
all distributions of principal and interest on the Class R Certificate other
than (i) distributions in respect of the Class SWR Interest and the Class LTR
Interest, and (ii) distributions on the Class R Certificate in respect of Excess
Interest.

     Responsible Officer: When used with respect to the Trustee or Servicer, any
officer of the Trustee or Servicer with direct responsibility for the
administration of this Agreement and also means any other officer to whom, with
respect to a particular matter, such matter is referred because of such
officer's knowledge of and familiarity with the particular subject.

     Reuters Screen LIBO Page: The display designated as page "LIBO" on the
Reuters Monitor Money Rates Service (or such other page as may replace such LIBO
page on that service for the purpose of displaying London interbank offered
rates of major banks).

     S&P: Standard & Poor's Ratings Services, a division of The McGraw-Hill
Companies, Inc., or its successor in interest.

     Sale Agreement: The Mortgage Loan Sale and Assignment Agreement, dated as
of March 1, 2007, between the Depositor and the Sponsor.

      Sarbanes-Oxley Certification: As defined in Section 3.20 hereof.

     Scheduled Payment: The scheduled monthly payment on a Mortgage Loan due on
any Due Date allocable to principal and/or interest on such Mortgage Loan.

     Section 302 Requirements: Any rules or regulations promulgated pursuant to
the Sarbanes-Oxley Act of 2002 (as such may be amended from time to time).

     Securities Act: The Securities Act of 1933, as amended.

     Servicer: Wilshire Credit Corporation, a Nevada corporation, or its
successor in interest.

     Servicer Remittance Date: With respect to any Distribution Date, the later
of (x) the date that is two Business Days after the 15th day of the month in
which the related Distribution Date occurs and (y)


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<PAGE>

the 18th day (or, if such day is not a Business Day, the next succeeding
Business Day) of the month in which the related Distribution Date occurs.

     Servicer's Assignee: As defined in Section 10.14(a).

     Servicing Advances: All customary, reasonable and necessary "out of pocket"
costs and expenses incurred in the performance by the Servicer of its servicing
obligations hereunder, including, but not limited to, the cost of (1) the
preservation, restoration and protection of a Mortgaged Property, including
without limitation advances in respect of prior liens, real estate taxes and
assessments, (2) any collection, enforcement or judicial proceedings, including
without limitation foreclosures, collections and liquidations, (3) the
conservation, management, sale and liquidation of any REO Property (4) executing
and recording instruments of satisfaction, deeds of reconveyance, substitutions
of trustees on deeds of trust or assignments of mortgage to the extent not
otherwise recovered from the related Mortgagor or payable under this Agreement,
(5) correcting errors of prior servicers; tax tracking; title research; flood
certification; and lender paid mortgage insurance, (6) obtaining or correcting
any legal documentation required to be included in the Mortgage Files and
reasonably necessary for the Servicer to perform its obligations under this
Agreement and (7) compliance with the obligations under Sections 3.01 and 3.10.

     Servicing Criteria: The "servicing criteria" set forth in Item 1122(d) of
Regulation AB, as such may be amended from time to time, and in Exhibit R of
this Agreement.

     Servicing Fee: As to each Mortgage Loan and any Distribution Date, an
amount equal to the product of (x) one-twelfth of the Servicing Fee Rate and (y)
the Stated Principal Balance of such Mortgage Loan as of the preceding
Distribution Date or, in the event of any payment of interest that accompanies a
Principal Prepayment in full made by the Mortgagor, interest at the Servicing
Fee Rate on the Stated Principal Balance of such Mortgage Loan as of the
preceding Distribution Date for the period covered by such payment of interest.

     Servicing Fee Rate: 0.500% per annum for each Mortgage Loan.

     Servicing Officer: Any officer of the Servicer involved in, or responsible
for, the administration and servicing of the Mortgage Loans whose name and
facsimile signature appear on a list of servicing officers furnished to the
Trustee by the Servicer on the Closing Date pursuant to this Agreement, as such
lists may from time to time be amended.

     Servicing Rights Pledgee: One or more lenders, selected by the Servicer, to
which the Servicer may pledge and assign all of its right, title and interest
in, to and under this Agreement.

     Servicing Transfer Costs: In the event that the Servicer does not reimburse
the Trustee under the this Agreement, all costs associated with the transfer of
servicing from the predecessor Servicer, including, without limitation, any
costs or expenses associated with the termination of the predecessor Servicer,
the appointment of a successor servicer, the complete transfer of all servicing
data and the completion, correction or manipulation of such servicing data as
may be required by the Trustee or any successor servicer to correct any errors
or insufficiencies in the servicing data or otherwise to enable the Trustee or
successor servicer to service the Mortgage Loans properly and effectively.

     SFAS 140: Statement of Financial Accounting Standard No. 140, Accounting
for Transfers and Servicing of Financial Assets and Extinguishments of
Liabilities dated September 2000, published by the Financial Accounting
Standards Board of the Financial Accounting Foundation.


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<PAGE>

     Significance Estimate: With respect to any Distribution Date, and in
accordance with Item 1115 of Regulation AB, shall be an amount determined based
on the reasonable good-faith estimate by the Depositor or its affiliate of the
aggregate maximum probable exposure of the outstanding Certificates to the Swap
Agreement.

     Significance Percentage: With respect to any Distribution Date, and in
accordance with Item 1115 of Regulation AB, shall be a percentage equal to the
Significance Estimate divided by the aggregate outstanding Stated Principal
Balance of the Mortgage Loans, prior to the distribution of the Principal
Distribution Amount on such Distribution Date.

     Sponsor: Merrill Lynch Mortgage Lending, Inc., a Delaware corporation, or
its successor in interest.

     SPV: As defined in Section 10.14(a).

     Startup Day: As defined in Section 2.07 hereof.

     Stated Principal Balance: With respect to any Mortgage Loan or related REO
Property (1) as of the Cut-off Date, the Cut-off Date Principal Balance thereof,
and (2) as of any Distribution Date, such Cut-off Date Principal Balance, minus
the sum of (A) the principal portion of the Scheduled Payments (x) due with
respect to such Mortgage Loan during each Due Period ending prior to such
Distribution Date and (y) that were received by the Servicer as of the close of
business on the Determination Date related to such Distribution Date or with
respect to which Advances were made on the Servicer Remittance Date prior to
such Distribution Date and (B) all unscheduled Principal Prepayments with
respect to such Mortgage Loan received on or prior to the last day of the
related Prepayment Period, and all Liquidation Proceeds to the extent applied by
the Servicer as recoveries of principal in accordance with Section 3.12 with
respect to such Mortgage Loan, that were received by the Servicer as of the
close of business on the last day of the related Prepayment Period.
Notwithstanding the foregoing, the Stated Principal Balance of a Liquidated Loan
shall be deemed to be zero.

     Stepdown Date: The earlier to occur of (1) the first Distribution Date on
which the Class A Certificate Principal Balance and the Class R Certificate
Principal Balance have been reduced to zero and (2) the later to occur of (A)
the Distribution Date in April 2010 or (B) the first Distribution Date on which
the Class A Certificate Principal Balance (after giving effect to distributions
of the Principal Funds amount for such Distribution Date) is less than or equal
to 73.40% of the aggregate Stated Principal Balance of the Mortgage Loans as of
the end of the immediately preceding Due Period.

     Stepdown Required Loss Percentage: For any Distribution Date, the
applicable percentage for such Distribution Date set forth in the following
table:

<TABLE>
<CAPTION>
DISTRIBUTION DATE OCCURRING IN    STEPDOWN REQUIRED LOSS PERCENTAGE
------------------------------    ---------------------------------
<S>                               <C>
April 2009 - March 2010           0.95% with respect to April 2009, plus an
                                 additional 1/12th of 1.15% for each month
                                 thereafter

April 2010 -March 2011            2.10% with respect to April 2010, plus an
                                 additional 1/12th of 1.20% for each month
                                 thereafter

April 2011 -March 2012            3.30% with respect to April 2011, plus an
                                 additional 1/12th of 0.95% for each month
                                  thereafter

April 2012 - March 2013           4.25% with respect to April 2012, plus an
                                 additional 1/12th of 0.55% for each month
                                 thereafter

April 2013 and thereafter         4.80%
</TABLE>


                                       57

<PAGE>

     Stepdown Trigger Event: With respect to the Certificates on or after the
Stepdown Date, a Distribution Date on which (1) the quotient of (A) the
aggregate Stated Principal Balance of all Mortgage Loans which are sixty (60) or
more days Delinquent measured on a rolling three month basis (including, for the
purposes of this calculation, Mortgage Loans in foreclosure, REO Properties and
Mortgage Loans with respect to which the applicable Mortgagor is in bankruptcy)
and (B) the Stated Principal Balance of the Mortgage Loans as of the preceding
Servicer Remittance Date, equals or exceeds the product of (i) 34.30% and (ii)
the Required Percentage or (2) the quotient (expressed as a percentage) of (A)
the aggregate Realized Losses incurred from the Cut-off Date through the last
day of the calendar month preceding such Distribution Date and (B) the aggregate
principal balance of the Mortgage Loans as of the Cut-off Date exceeds the
Stepdown Required Loss Percentage.

     Subcontractor: Any outsourcer that performs one or more discrete functions
identified in Item 1122(d) of Regulation AB with respect to 5% or more of the
Mortgage Loans under the direction or authority of a Servicer (measured by
aggregate Stated Principal Balance of the Mortgage Loans, annually at the
commencement of the calendar year prior to the year in which an Assessment of
Compliance is required to be delivered, multiplied by a fraction, the numerator
of which is the number of months during which such Subcontractor performs such
discrete functions and the denominator of which is 12, or, in the case of the
year in which the Closing Date occurs, the number of months elapsed in such
calendar year).

     Subordinate Certificate Available Funds Cap: With respect to a Distribution
Date, the per annum rate equal to the weighted average (weighted in proportion
to the results of subtracting from the aggregate Stated Principal Balance of
each Mortgage Group, the current Certificate Principal Balance of the Class A-1
and Class R Certificates, in the case of Group One, or the Class A-2A, Class
A-2B, Class A-2C and Class A-2D Certificates, in the case of Group Two) of the
Class A-1 Available Funds Cap and the Class A-2 Available Funds Cap.

     Subordinate Certificate Corridor Contract: The confirmation and agreement
(together with the schedule thereto) and any related credit support annex
(attached as Exhibit O-4 hereto), between the Trustee, on behalf of the Issuing
Entity, and the Cap Contract Counterparty (attached as Exhibit O-3 hereto), with
respect to the Subordinate Certificates.

     Subordinate Certificate Corridor Contract Notional Balance: With respect to
any Distribution Date, the Subordinate Certificate Corridor Contract Notional
Balance set forth for such Distribution Date in the Subordinate Certificate
LIBOR Cap Table attached as Schedule I to Exhibit O-3.

     Subordinate Certificate Corridor Contract Termination Date: The day after
the Distribution Date in September 2007.

     Subordinate Certificate Maximum Rate Cap: With respect to a Distribution
Date, the per annum rate equal to the weighted average (weighted in proportion
to the results of subtracting from the aggregate Stated Principal Balance of
each Mortgage Group, the current Certificate Principal Balance of the Class A-1
and Class R Certificates, in the case of Group One, or the Class A-2A, Class
A-2B, Class A-2C and Class A-2D Certificates, in the case of Group Two) of the
Class A-1 Maximum Rate Cap and the Class A-2 Maximum Rate Cap.

     Subordinate Certificate Upper Collar: With respect to each Distribution
Date with respect to which payments are received on the Subordinate Certificate
Corridor Contract, a rate equal to the lesser of One-Month LIBOR and 8.950% per
annum.

     Subordinate Certificates: The Class M and Class B Certificates.


                                       58

<PAGE>

     Subsequent Recovery: The amount, if any, recovered by the Servicer with
respect to a Liquidated Loan with respect to which a Realized Loss has been
incurred after liquidation and disposition of such Mortgage Loan.

     Subservicer: Any Person that services Mortgage Loans on behalf of the
Servicer pursuant to a subservicing agreement and is responsible for the
performance of the material servicing functions required to be performed by the
Servicer under this Agreement that are identified in Item 1122(d) of Regulation
AB with respect to 10% or more of the Mortgage Loans under the direction or
authority of the Servicer (measured by aggregate Stated Principal Balance of the
Mortgage Loans, annually at the commencement of the calendar year prior to the
year in which an Assessment of Compliance is required to be delivered,
multiplied by a fraction, the numerator of which is the number of months during
which such Subservicer services the related Mortgage Loans and the denominator
of which is 12, or, in the case of the year in which the Closing Date occurs,
the number of months elapsed in such calendar year). Any subservicer shall meet
the qualifications set forth in Section 3.02.

     Subservicing Agreement: As defined in Section 3.02(a).

     Substitution Adjustment Amount: The meaning ascribed to such term pursuant
to Section 2.03(c).

     Supplemental Interest Trust: The separate trust, established pursuant to
Section 4.04(l) of this Agreement and held by the Trustee for the benefit of the
holders of the Certificates as a segregated subtrust of the Trust Fund, in which
the Swap Agreement will be held, out of which any Swap Termination Payments or
Net Swap Payments owed to the Swap Counterparty will be paid, certain
distributions to Certificateholders will be made, and into which any Swap
Termination Payments or Net Swap Payments received from the Swap Counterparty
will be deposited as set forth in Section 4.04 hereof.

     Supplemental Interest Trust Trustee: U.S. Bank National Association, a
national banking association, not in its individual capacity, but solely in its
capacity as trustee of the Supplemental Interest Trust under this Agreement, and
any successor thereto, and any corporation or national banking association
resulting from or surviving any consolidation or merger to which it or its
successors may be a party and any successor trustee as may from time to time be
serving as successor trustee hereunder.

     Swap Account: The separate Eligible Account created and maintained by the
Supplemental Interest Trust Trustee pursuant to Section 4.04(l) in the name of
the Supplemental Interest Trust Trustee for the benefit of the Supplemental
Interest Trust and designated "U.S. Bank National Association, as trustee, in
trust for registered holders of Specialty Underwriting and Residential Finance
Trust, Mortgage Loan Asset-Backed Certificates, Series 2007-AB1." Funds in the
Swap Account shall be held in trust for the Supplemental Interest Trust Trustee
for the uses and purposes set forth in this Agreement.

     Swap Agreement: The confirmation and agreement (together with the schedule
thereto), and the related credit support annex (attached as Exhibit U-2),
between the Swap Counterparty and the Supplemental Interest Trust Trustee for
the benefit of the Issuing Entity (attached as Exhibit U-1).

     Swap Counterparty: The Bank of New York, or any successor counterparty who
meets the requirements set forth in the Swap Agreement.

     Swap LIBOR: With respect to any Distribution Date (and the related Accrual
Period) the product of (i) the Floating Rate Option (as defined in the Swap
Agreement for the related Swap Payment Date),


                                        59

<PAGE>

(ii) two and (iii) the quotient of (a) the actual number of days in the Accrual
Period for the Lower Tier REMIC Interests divided by (b) 30.

     Swap Payment Date: For so long as the Swap Agreement is in effect or
amounts remain unpaid thereunder, two Business Days immediately preceding each
Distribution Date.

     Swap Posted Collateral Account: The segregated Eligible Account that may be
created and maintained by the Supplemental Interest Trust Trustee pursuant to
Section 4.04(l) in the name of the Supplemental Interest Trust Trustee for the
benefit of the Supplemental Interest Trust and designated "U.S. Bank National
Association, as trustee, in trust for registered holders of Specialty
Underwriting and Residential Finance Trust, Mortgage Loan Asset-Backed
Certificates, Series 2007-AB1." Funds in the Swap Posted Collateral Account
shall be held in trust for the Supplemental Interest Trust for the uses and
purposes set forth in the Swap Agreement.

     SWAP REMIC: As described in the Preliminary Statement and Section 2.07.

     SWAP REMIC Interests: Each of the interests in the SWAP REMIC as set forth
in the Preliminary Statement.

     SWAP REMIC Regular Interests: Each of the SWAP REMIC Interests other than
the Class SWR Interest.

     Swap Termination Payment: Any payment payable by the Supplemental Interest
Trust or the Swap Counterparty upon termination of the Swap Agreement as a
result of termination of the Swap Agreement.

     Targeted Overcollateralization Amount: As of any Determination Date, (a)
prior to the Stepdown Date, 1.80% of the Cut-Off Date Principal Balance of the
Mortgage Loans and (b) on or after the Stepdown Date, 3.60% of the Stated
Principal Balance of the Mortgage Loans.

     Tax Matters Person: The Person designated as "tax matters person" in the
manner provided under Treasury regulation Section 1.860F-4(d) and Treasury
regulation Section 301.6231(a)(7)-1.

     Transfer: Any direct or indirect transfer or sale of any Ownership Interest
in a Certificate.

     Trust Fund: The corpus of the Issuing Entity created hereunder consisting
of (i) the Mortgage Loans and all interest and principal received on or with
respect thereto on and after the Cut-off Date to the extent not applied in
computing the Cut-off Date Principal Balance thereof, exclusive of interest not
required to be deposited in the Collection Account; (ii) the Collection Account
and the Certificate Account and all amounts deposited therein pursuant to the
applicable provisions of this Agreement; (iii) property that secured a Mortgage
Loan and has been acquired by foreclosure, deed in lieu of foreclosure or
otherwise; (iv) the mortgagee's rights under the Insurance Policies with respect
to the Mortgage Loans and/or the related Mortgaged Properties; (v) all proceeds
of the conversion, voluntary or involuntary, of any of the foregoing into cash
or other liquid property; (vi) the Corridor Contracts and the Corridor Contract
Account; and (vii) the Supplemental Interest Trust that in turn holds the Swap
Agreement.

     Trustee: U.S. Bank National Association, a national banking association,
not in its individual capacity, but solely in its capacity as trustee for the
benefit of the Certificateholders under this Agreement, and any successor
thereto, and any corporation or national banking association resulting from or
surviving any consolidation or merger to which it or its successors may be a
party and any successor trustee as may from time to time be serving as successor
trustee hereunder.


                                       60

<PAGE>

     Uncertificated Class C Interest: An uncertificated REMIC Regular Interest
having the characteristics described in the Preliminary Statement.

     Unpaid Realized Loss Amount: The Class M-1 Unpaid Realized Loss Amount,
Class M-2 Unpaid Realized Loss Amount, Class M-3 Unpaid Realized Loss Amount,
Class M-4 Unpaid Realized Loss Amount, Class M-5 Unpaid Realized Loss Amount,
Class M-6 Unpaid Realized Loss Amount, Class B-1 Unpaid Realized Loss Amount,
Class B-2 Unpaid Realized Loss Amount, Class B-3 Unpaid Realized Loss Amount and
Class C Unpaid Realized Loss Amount, collectively.

     Upper Collar: Any of the Class A-1 Upper Collar, the Class A-2 Upper Collar
or the Subordinate Certificate Upper Collar.

     Upper Tier REMIC: As described in the Preliminary Statement and Section
2.07.

     Upper Tier REMIC Net WAC Cap: In the case of the Class UTA-1 Interest and
the Residual Interest, a per annum rate equal to the weighted average of the
interest rate of the Class LTII1B Interest for such Distribution Date. In the
case of the Class UTA-2A, Class UTA-2B, Class UTA-2C and Class UTA-2D Interests,
a per annum rate equal to the weighted average of the interest rate for the
Class LTII2B for such Distribution Date. In the case of the Class UTM-1, Class
UTM-2, Class UTM-3, Class UTM-4, Class UTM-5, Class UTM-6, Class UTB-1, Class
UTB-2 and Class UTB-3 Interests, a per annum rate equal to the weighted average
of the interest rates of Class LTII1B and Class LTII2B Interests for such
Distribution weighted, respectively, on the basis of the uncertificated
principal balances of the Class LTII1A and the Class LTII2A Interests. In the
case of any interest in the Upper Tier REMIC that accrues interest on a "30/360"
basis, the per annum rates described in this definition shall be adjusted to
reflect accruals on such basis.

     Voting Rights: The portion of the voting rights of all the Certificates
that is allocated to any of the Certificates for purposes of the voting
provisions hereunder. Voting Rights allocated to each Class of Certificates
shall be allocated 98% to the Offered Certificates, 2% to the Class C and Class
P Certificates, with the allocation among the Offered Certificates to be in
proportion to the Class Certificate Principal Balance of each Class relative to
the Class Certificate Principal Balance of all other Classes. Voting Rights will
be allocated among the Certificates of each such Class in accordance with their
respective Percentage Interests.

                                    ARTICLE II
          CONVEYANCE OF MORTGAGE LOANS; REPRESENTATIONS AND WARRANTIES

     SECTION 2.01. Conveyance of Mortgage Loans.

     The Depositor, concurrently with the execution and delivery hereof, does
hereby sell, transfer, assign, set over and convey to the Trustee without
recourse all the right, title and interest of the Depositor in and to the assets
of the Trust Fund. Such assignment includes all interest and principal received
on or with respect to the Mortgage Loans on or after the Cut-off Date (other
than Scheduled Payments due on the Mortgage Loans on or before the Cut-off
Date).

     In connection with such assignment, the Depositor does hereby deliver to,
and deposit with, the Trustee the following documents or instruments with
respect to each Mortgage Loan so assigned:

     (a) all pages of the original Mortgage Note, signed by the borrower(s) and
endorsed, "Pay to the order of blank, without recourse" and signed in the name
of the prior holder by an authorized officer. Such signature on the endorsement
shall be an original signature of such authorized officer and have


                                       61

<PAGE>

printed the endorser's name, title and company name. To the extent that there is
no room on the face of the Mortgage Note for endorsements, the endorsement may
be contained on an allonge, if the law by which such Mortgage Note is governed
so permits. The Mortgage Note shall include all intervening endorsements showing
a complete chain of title from the originator to the Sponsor;

     (b) all original pages of any riders referred to in the Mortgage Note;

     (c) for each Mortgage Loan that is not a MOM Mortgage Loan, the original
recorded Mortgage, together with all riders referred to in the Mortgage, and
legal description, with evidence of recording thereon or if the original is not
available, a copy certified by the applicable public recording office. If the
original Mortgage has not yet been returned from the recording office, a copy of
the original Mortgage, together with all riders thereto, that has been delivered
for recording in the appropriate recording office of the jurisdiction in which
the Mortgaged Property is located;

     (d) for each Mortgage Loan that is not a MERS Mortgage Loan, the original
Mortgage Assignment, executed in blank, in form and substance acceptable for
recording and signed in the name of the last endorsee by an authorized officer;

     (e) the policy of title insurance (or a preliminary title report if the
original title insurance policy has not been received from the title insurance
company);

     (f) for each Mortgage Loan that is not a MERS Mortgage Loan, originals of
any intervening Mortgage Assignments, with evidence of recording thereon, or if
the original is not available, a copy certified by the applicable public
recording office. If the original intervening assignment has not yet been
returned from the recording office, a copy of such assignment which has been
sent for recording in the appropriate jurisdiction in which the Mortgaged
Property is located, showing a complete chain of title from the originator to
the Seller;

     (g) in the case of each MOM Loan, the original Mortgage, together with all
riders thereto, with evidence of recording thereon, noting the presence of the
MIN of the Mortgage Loan and language indicating that the Mortgage Loan is a MOM
Loan or if the original Mortgage is not available, a copy certified by the
applicable public recording office. If the original Mortgage has not yet been
returned from the recording office, a copy of such Mortgage which has been sent
for recording in the appropriate jurisdiction in which the Mortgaged Property is
located;

     (h) in the case of each MERS Mortgage Loan that is not a MOM Loan, the
original Mortgage Assignment or if the original Mortgage is not available, a
copy certified by the applicable public recording office, with evidence of
recording thereon, and all intervening Mortgage Assignments, with evidence of
recording thereon, showing a complete chain of title from the originator to
MERS;

     (i) all original pages of assumption, modification, consolidation or
extension agreements, if any, with evidence of recording thereon;

     (j) with respect to a Mortgage Loan that, according to the Mortgage Loan
Schedule is covered by a primary mortgage insurance policy, the original or a
copy of the policy of primary mortgage insurance; and

     (k) if the Mortgage Note or the Mortgage has been signed by any Person on
behalf of the Mortgagor, the original power of attorney or other instrument that
authorized and empowered such Person to sign, or a copy of such power of
attorney that has been delivered for recording in the appropriate recording
office of the jurisdiction in which the Mortgaged Property is located.


                                       62

<PAGE>

     If in connection with any Mortgage Loan, the Depositor cannot deliver the
Mortgage, Assignments of Mortgage or assumption, consolidation or modification,
as the case may be, with evidence of recording thereon, if applicable,
concurrently with the execution and delivery of this Agreement solely because of
a delay caused by the public recording office where such Mortgage, Assignments
of Mortgage or assumption, consolidation or modification, as the case may be,
has been delivered for recordation, the Depositor shall deliver or cause to be
delivered to the Trustee written notice stating that such Mortgage or
assumption, consolidation or modification, as the case may be, has been
delivered to the appropriate public recording office for recordation.
Thereafter, the Depositor shall deliver or cause to be delivered to the Trustee
such Mortgage, Assignments of Mortgage or assumption, consolidation or
modification, as the case may be, with evidence of recording indicated thereon,
if applicable, upon receipt thereof from the public recording office. To the
extent any required endorsement is not contained on a Mortgage Note or an
Assignment of Mortgage, the Depositor shall make or cause to be made such
endorsement.

     With respect to any Mortgage Loan, none of the Depositor, the Servicer or
the Trustee shall be obligated to cause to be recorded the Assignment of
Mortgage referred to in this Section 2.01. In the event that any Assignment of
Mortgage is not recorded or is improperly recorded, the Servicer shall have no
liability for its failure to receive or act on notices related to such
Assignment of Mortgage.

     The ownership of each Mortgage Note, the Mortgage and the contents of the
related Mortgage File is vested in the Trustee. Neither the Depositor nor the
Servicer shall take any action inconsistent with such ownership and shall not
claim any ownership interest therein. The Depositor and the Servicer shall
respond to any third party inquiries with respect to ownership of the Mortgage
Loans by stating that such ownership is held by the Trustee on behalf of the
Certificateholders. Mortgage documents relating to the Mortgage Loans not
delivered to the Trustee are and shall be held in trust by the Servicer, for the
benefit of the Trustee as the owner thereof, and the Servicer's possession of
the contents of each Mortgage File so retained is for the sole purpose of
servicing the related Mortgage Loan, and such retention and possession by the
Servicer is in a custodial capacity only. The Depositor agrees to take no action
inconsistent with the Trustee's ownership of the Mortgage Loans, to promptly
indicate to all inquiring parties that the Mortgage Loans have been sold and to
claim no ownership interest in the Mortgage Loans.

     It is the intention of this Agreement that the conveyance of the
Depositor's right, title and interest in and to the Trust Fund pursuant to this
Agreement shall constitute a purchase and sale and not a loan. If a conveyance
of Mortgage Loans from the Sponsor to the Depositor is characterized as a pledge
and not a sale, then the Depositor shall be deemed to have transferred to the
Trustee all of the Depositor's right, title and interest in, to and under the
obligations of the Sponsor deemed to be secured by said pledge; and it is the
intention of this Agreement that the Depositor shall also be deemed to have
granted to the Trustee a first priority security interest in all of the
Depositor's right, title, and interest in, to and under the obligations of the
Sponsor to the Depositor deemed to be secured by said pledge and that the
Trustee shall be deemed to be an independent custodian for purposes of
perfection of the security interest granted to the Depositor. If the conveyance
of the Mortgage Loans from the Depositor to the Trustee is characterized as a
pledge, it is the intention of this Agreement that this Agreement shall
constitute a security agreement under applicable law, and that the Depositor
shall be deemed to have granted to the Trustee a first priority security
interest in all of the Depositor's right, title and interest in, to and under
the Mortgage Loans, all payments of principal of or interest on such Mortgage
Loans, all other rights relating to and payments made in respect of the Trust
Fund, and all proceeds of any thereof. If the trust created by this Agreement
terminates prior to the satisfaction of the claims of any Person in any
Certificates, the security interest created hereby shall continue in full force
and effect and the Trustee shall be deemed to be the collateral agent for the
benefit of such Person.


                                       63

<PAGE>

     In addition to the conveyance made in the first paragraph of this Section
2.01, the Depositor does hereby convey, assign and set over to the Trustee for
the benefit of the Certificateholders its rights and interests under the Sale
Agreement, including the Depositor's right, title and interest in the
representations and warranties contained in the Sale Agreement and the benefit
of the repurchase obligations and the obligation of the Sponsor contained in the
Sale Agreement to take, at the request of the Depositor or the Trustee, all
action on its part which is reasonably necessary to ensure the enforceability of
a Mortgage Loan. The Trustee hereby accepts such assignment, and shall be
entitled to exercise all rights of the Depositor under the Sale Agreement as if,
for such purpose, it were the Depositor. The foregoing sale, transfer,
assignment, set-over, deposit and conveyance does not and is not intended to
result in creation or assumption by the Trustee of any obligation of the
Depositor, the Sponsor, or any other Person in connection with the Mortgage
Loans or any other agreement or instrument relating thereto.

     The parties hereto agree and understand that it is not intended that any
Mortgage Loan be included in the Trust that is, without limitation, a "High-Cost
Home Loan" as defined by the Home Ownership and Equity Protection Act of 1994 or
any other applicable anti-predatory lending laws, including but not limited to
(i) a "High-Cost Home Loan" as defined in the New Jersey Home Ownership Act
effective November 27, 2003; (ii) a "High-Cost Home Loan" as defined in the New
Mexico Home Loan Protection Act effective January 1, 2004; (iii) a "High-Cost
Home Loan" as defined in the Massachusetts Predatory Home Loan Practices Act
effective November 7, 2004; (iv) a "High-Cost Home Loan" as defined by the
Indiana High Cost Home Loan Law effective January 1, 2005 or (v) a "High-Cost
Home Loan" as defined by the Illinois High Risk Home Loan Act effective January
1, 2004.

     SECTION 2.02. Acceptance by Trustee of the Mortgage Loans.

     Except as set forth in the Exception Report delivered contemporaneously
herewith (the "Exception Report"), the Trustee acknowledges receipt of the
Mortgage Note for each Mortgage Loan and delivery of a Mortgage File (but does
not acknowledge receipt of all documents required to be included in such
Mortgage File) with respect to each Mortgage Loan and declares that it holds and
will hold such documents and any other documents constituting a part of the
Mortgage Files delivered to it in trust for the use and benefit of all present
and future Certificateholders. The Depositor will cause the Sponsor to
repurchase any Mortgage Loan to which a material exception was taken in the
Exception Report unless such exception is cured to the satisfaction of the
Depositor and the Trustee within forty-five (45) Business Days of the Closing
Date.

     The Trustee acknowledges receipt of the three Corridor Contracts (attached
hereto as Exhibits O-1, O-2 and O-3). The Trustee also acknowledges receipt of
the Sale Agreement.

     The Trustee acknowledges receipt of the Swap Agreement that will be held in
the Supplemental Interest Trust and is hereby instructed to enter into the Swap
Agreement, not in its individual capacity, but solely as the Supplemental
Interest Trust Trustee.

     The Trustee agrees, for the benefit of Certificateholders, to review each
Mortgage File delivered to it within sixty (60) days after the Closing Date to
ascertain and to certify, within seventy (70) days of the Closing Date, to the
Depositor and the Servicer that all documents required by Section 2.01, except
those listed on the exception report attached thereto, have been executed and
received, and that such documents relate to the Mortgage Loans identified in
Exhibit B that have been conveyed to it. If the Trustee finds any document or
documents constituting a part of a Mortgage File to be missing or defective
(that is, mutilated, damaged, defaced or unexecuted) in any material respect,
the Trustee shall promptly (and in any event within no more than five Business
Days) after such finding so notify the Servicer, the Sponsor and the Depositor.
In addition, the Trustee shall also notify the Servicer, the Sponsor and the
Depositor if the original Mortgage with evidence of recording thereon with
respect to a


                                       64

<PAGE>

Mortgage Loan is not received within seventy (70) days of the Closing Date; if
it has not been received because of a delay caused by the public recording
office where such Mortgage has been delivered for recordation, the Depositor
shall deliver or cause to be delivered to the Trustee written notice stating
that such Mortgage has been delivered to the appropriate public recording office
for recordation and thereafter the Depositor shall deliver or cause to be
delivered such Mortgage with evidence of recording thereon upon receipt thereof
from the public recording office. The Trustee shall request that the Sponsor
correct or cure such omission, defect or other irregularity, or substitute a
Mortgage Loan pursuant to the provisions of Section 2.03(c), within ninety (90)
days from the date the Sponsor was notified of such omission or defect and, if
the Sponsor does not correct or cure such omission or defect within such period,
that the Sponsor purchase such Mortgage Loan from the Issuing Entity within
ninety (90) days from the date the Trustee notified the Sponsor of such
omission, defect or other irregularity at the Purchase Price of such Mortgage
Loan. The Purchase Price for any Mortgage Loan purchased pursuant to this
Section 2.02 shall be paid to the Servicer and deposited by the Servicer in the
Collection Account promptly upon receipt, and, upon receipt by the Trustee of
written notification of such deposit signed by a Servicing Officer, the Trustee,
upon receipt of a Request for Release, shall promptly release to the Sponsor the
related Mortgage File and the Trustee shall execute and deliver such instruments
of transfer or assignment, without recourse, representation or warranty, as
shall be necessary to vest in the Sponsor or its designee, as the case may be,
any Mortgage Loan released pursuant hereto, and the Trustee shall have no
further responsibility with regard to such Mortgage Loan. It is understood and
agreed that the obligation of the Sponsor to purchase, cure or substitute any
Mortgage Loan as to which a material defect in or omission of a constituent
document exists shall constitute the sole remedy respecting such defect or
omission available to the Trustee on behalf of Certificateholders. The preceding
sentence shall not, however, limit any remedies available to the
Certificateholders, the Depositor or the Trustee pursuant to the Sale Agreement.
The Trustee shall be under no duty or obligation to inspect, review and examine
such documents, instruments, certificates or other papers to determine that they
are genuine, enforceable, recordable or appropriate to the represented purpose,
or that they have actually been recorded, or that they are other than what they
purport to be on their face. The Trustee shall keep confidential the name of
each Mortgagor and the Trustee shall not solicit any such Mortgagor for the
purpose of refinancing the related Mortgage Loan. It is understood and agreed
that all rights and benefits relating to the solicitation of any Mortgagors and
the attendant rights, title and interest in and to the list of Mortgagors and
data relating to their Mortgages shall be retained by the Servicer.

     Within seventy (70) days of the Closing Date, the Trustee shall deliver to
the Depositor and the Servicer the Trustee's Certification, substantially in the
form of Exhibit D attached hereto, evidencing the completeness of the Mortgage
Files, with any exceptions noted thereto.

     SECTION 2.03. Representations, Warranties and Covenants of the Depositor.

     (a) The Depositor hereby represents and warrants to the Servicer and the
Trustee as follows, as of the date hereof

          (i) The Depositor is duly organized and is validly existing as a
     corporation in good standing under the laws of the State of Delaware and
     has full power and authority (corporate and other) necessary to own or hold
     its properties and to conduct its business as now conducted by it and to
     enter into and perform its obligations under this Agreement and the Sale
     Agreement.

          (ii) The Depositor has the full corporate power and authority to
     execute, deliver and perform, and to enter into and consummate the
     transactions contemplated by, this Agreement and the Sale Agreement and has
     duly authorized, by all necessary corporate action on its part, the
     execution, delivery and performance of this Agreement and the Sale
     Agreement; and this Agreement and the Sale Agreement, assuming the due
     authorization, execution and delivery


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      hereof by the other parties hereto, constitutes a legal, valid and binding
     obligation of the Depositor, enforceable against the Depositor in
     accordance with its terms, subject, as to enforceability, to (i)
     bankruptcy, insolvency, reorganization, moratorium and other similar laws
     affecting creditors' rights generally and (ii) general principles of
     equity, regardless of whether enforcement is sought in a proceeding in
     equity or at law.

          (iii) The execution and delivery of this Agreement and the Sale
     Agreement by the Depositor, the consummation of the transactions
     contemplated by this Agreement and the Sale Agreement, and the fulfillment
     of or compliance with the terms hereof are in the ordinary course of
     business of the Depositor and will not (A) result in a material breach of
     any term or provision of the charter or by-laws of the Depositor or (B)
     materially conflict with, result in a violation or acceleration of, or
     result in a material default under, the terms of any other material
     agreement or instrument to which the Depositor is a party or by which it
     may be bound or (C) constitute a material violation of any statute, order
     or regulation applicable to the Depositor of any court, regulatory body,
     administrative agency or governmental body having jurisdiction over the
     Depositor; and the Depositor is not in breach or violation of any material
     indenture or other material agreement or instrument, or in violation of any
     statute, order or regulation of any court, regulatory body, administrative
     agency or governmental body having jurisdiction over it which breach or
     violation may materially impair the Depositor's ability to perform or meet
     any of its obligations under this Agreement.

          (iv) No litigation is pending or, to the best of the Depositor's
     knowledge, threatened, against the Depositor that would materially and
     adversely affect the execution, delivery or enforceability of this
     Agreement and the Sale Agreement or the ability of the Depositor to perform
     its obligations under this Agreement and the Sale Agreement in accordance
     with the terms hereof.

          (v) No consent, approval, authorization or order of any court or
     governmental agency or body is required for the execution, delivery and
     performance by the Depositor of, or compliance by the Depositor with, this
     Agreement and the Sale Agreement or the consummation of the transactions
      contemplated hereby, or if any such consent, approval, authorization or
     order is required, the Depositor has obtained the same. The Depositor
     hereby represents and warrants to the Trustee with respect to each Mortgage
     Loan as of the Closing Date, and following the transfer of the Mortgage
     Loans to it by the Sponsor, the Depositor had good title to the Mortgage
     Loans and the Mortgage Notes were subject to no offsets, claims, liens,
     mortgage, pledge, charge, security interest, defenses or counterclaims.

          (vi) Each Mortgage Loan in Group One has a Stated Principal Balance as
     of the Cut-off Date that complies with the loan limitations of Fannie Mae
     and Freddie Mac as in effect on the Cut-off Date.

     (b) To the extent that any fact, condition or event with respect to a
Mortgage Loan constitutes a breach of a representation or warranty of the
Sponsor under the Sale Agreement, the only right or remedy of the Trustee or of
any Certificateholder shall be the Trustee's right to enforce the obligations of
the Sponsor under any applicable representation or warranty made by it. The
Trustee acknowledges that the Depositor shall have no obligation or liability
with respect to any breach of any representation or warranty with respect to the
Mortgage Loans (except as set forth in Section 2.03(a)(v)) under any
circumstances.

     (c) Upon discovery by any of the Depositor, the Servicer, or the Trustee of
a breach of any of representations and warranties set forth in the Sale
Agreement that adversely and materially affects the


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value of the related Mortgage Loan, prepayment charges or the interests of the
Certificateholders, the party discovering such breach shall give prompt written
notice to the other parties. Within ninety (90) days of the discovery of a
breach of any representation or warranty given to the Trustee by the Depositor,
the Sponsor and assigned by the Depositor to the Trustee, the Depositor, or the
Sponsor shall either (a) cure such breach in all material respects, (b)
repurchase such Mortgage Loan or any property acquired in respect thereof from
the Trustee at the Purchase Price or (c) within the two year period following
the Closing Date, substitute a Replacement Mortgage Loan for the affected
Mortgage Loan. In the event of discovery of a breach of any representation and
warranty of the Sponsor or the Depositor, the Trustee shall enforce its rights
under the Sale Agreement or thereunder for the benefit of Certificateholders. In
the event of a breach of the representations and warranties with respect to the
Mortgage Loans set forth in a Sale Agreement, the Trustee shall enforce the
right of the Issuing Entity to be indemnified for such breach of representation
and warranty. In the event that such breach relates solely to the
unenforceability of a prepayment charge, amounts received in respect of such
indemnity up to the amount of such prepayment charge shall be distributed
pursuant to Section 4.04(b)(i)(B). As provided in the Sale Agreement, if the
Sponsor substitutes for a Mortgage Loan for which there is a breach of any
representations and warranties which adversely and materially affects the value
of such Mortgage Loan and such substitute mortgage loan is not a Replacement
Mortgage Loan, under the terms of the Sale Agreement, the Sponsor will, in
exchange for such substitute Mortgage Loan, (i) provide the applicable Purchase
Price for the affected Mortgage Loan or (ii) within two years of the Closing
Date, substitute such affected Mortgage Loan with a Replacement Mortgage Loan.
Any such substitution shall not be effected prior to the additional delivery to
the Trustee of a Request for Release substantially in the form of Exhibit I and
shall not be effected unless it is within two years of the Startup Day. As
provided in the Sale Agreement, the Sponsor indemnifies and holds the Issuing
Entity, the Trustee, the Depositor, the Servicer and each Certificateholder
harmless against any and all taxes, claims, losses, penalties, fines,
forfeitures, reasonable legal fees and related costs, judgments, and any other
costs, fees and expenses that the Issuing Entity, the Trustee, the Depositor,
the Servicer and any Certificateholder may sustain in connection with any
actions of the Sponsor relating to a repurchase of a Mortgage Loan other than in
compliance with the terms of this Section 2.03 and the Sale Agreement, to the
extent that any such action causes (i) any federal or state tax to be imposed on
the Issuing Entity or any REMIC provided for herein, including without
limitation, any federal tax imposed on "prohibited transactions" under Section
860F(a)(1) of the Code or on "contributions after the startup day" under Section
860G(d)(1) of the Code, or (ii) any REMIC created hereunder to fail to qualify
as a REMIC at any time that any Certificate is outstanding.

     With respect to any Mortgage Loan repurchased by the Depositor pursuant to
this Agreement or by the Sponsor pursuant to the Sale Agreement, the principal
portion of the funds received by the Servicer in respect of such repurchase of a
Mortgage Loan will be considered a Principal Prepayment and shall be deposited
by the Servicer in the Certificate Account pursuant to Section 3.05. The
Trustee, upon receipt of the full amount of the Purchase Price for a Deleted
Mortgage Loan, or upon receipt of the Mortgage File for a Replacement Mortgage
Loan substituted for a Deleted Mortgage Loan, shall release or cause to be
released and reassign to the Depositor or the Sponsor, as applicable, the
related Mortgage File for the Deleted Mortgage Loan and shall execute and
deliver such instruments of transfer or assignment, in each case without
recourse, representation or warranty, as shall be necessary to vest in such
party or its designee or assignee title to any Deleted Mortgage Loan released
pursuant hereto, free and clear of all security interests, liens and other
encumbrances created by this Agreement, which instruments shall be prepared by
the Trustee, and the Trustee shall not have any further responsibility with
respect to the Mortgage File relating to such Deleted Mortgage Loan.

     With respect to each Replacement Mortgage Loan to be delivered to the
Trustee pursuant to the terms of this Article II in exchange for a Deleted
Mortgage Loan: (i) the Depositor or the Sponsor, as applicable, must deliver to
the Trustee the Mortgage File for the Replacement Mortgage Loan containing


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the documents set forth in Section 2.01 along with a written certification
certifying as to the delivery of such Mortgage File and containing the granting
language set forth in the first sentence of Section 2.01; and (ii) the Depositor
will be deemed to have made, with respect to such Replacement Mortgage Loan,
each of the representations and warranties made by it with respect to the
related Deleted Mortgage Loan. The Trustee shall review the Mortgage File with
respect to each Replacement Mortgage Loan and certify to the Depositor that all
documents required by Section 2.01 have been executed and received.

     For any month in which the Sponsor substitutes one or more Replacement
Mortgage Loans for one or more Deleted Mortgage Loans, the Sponsor will
determine the amount (if any) by which the aggregate principal balance of all
such Replacement Mortgage Loans as of the date of substitution and the aggregate
prepayment charges with respect to such Replacement Mortgage Loans is less than
the aggregate Stated Principal Balance (after application of the principal
portion of the Scheduled Payment due in the month of substitution) and aggregate
prepayment charges of all such Deleted Mortgage Loans. An amount equal to the
aggregate of the deficiencies described in the preceding sentence (such amount,
the "Substitution Adjustment Amount") shall be delivered by the Sponsor to the
Servicer for deposit into the Collection Account on the Determination Date for
the Distribution Date relating to the Prepayment Period during which the related
Mortgage Loan became required to be purchased or replaced hereunder.

     The Sponsor shall give or cause to be given written notice to the
Certificateholders that such substitution has taken place, shall amend the
Mortgage Loan Schedule to reflect the removal of such Deleted Mortgage Loan from
the terms of this Agreement and the substitution of the Replacement Mortgage
Loan or Replacement Mortgage Loans and shall deliver a copy of such amended
Mortgage Loan Schedule to the Trustee. Upon such substitution by the Sponsor,
such Replacement Mortgage Loan or Replacement Mortgage Loans shall constitute
part of the Mortgage Pool and shall be subject in all respects to the terms of
this Agreement and the Sale Agreement, including all applicable representations
and warranties thereof included in the Sale Agreement as of the date of
substitution.

     In addition, the Sponsor shall obtain at its own expense and deliver to the
Trustee an Opinion of Counsel addressed to the Trustee to the effect that such
substitution will not (a) cause any federal tax to be imposed on the Issuing
Entity or any REMIC provided for herein, including without limitation, any
federal tax imposed on "prohibited transactions" under Section 860F(a)(1) of the
Code or on "contributions after the startup day" under Section 860G(d)(1) of the
Code or (b) adversely affect the status of any REMIC provided for herein as a
REMIC. If any such Opinion of Counsel can not be delivered, then such
substitution may only be effected at such time as the required Opinion of
Counsel can be given.

     (d) It is understood and agreed that the representations, warranties and
indemnification (i) set forth in this Section 2.03 and (ii) of the Sponsor and
the Depositor set forth in the Sale Agreement and assigned to the Trustee by the
Depositor hereunder shall each survive delivery of the Mortgage Files and the
Assignment of Mortgage of each Mortgage Loan to the Trustee and shall continue
throughout the term of this Agreement.

     SECTION 2.04. Representations and Warranties of the Servicer.

      The Servicer hereby represents and warrants to the Depositor and the
Trustee as follows, as of the date hereof

          (i) The Servicer is a duly formed corporation and is validly existing
     and in good standing under the laws of the state of its formation and is
     duly authorized and qualified to transact any and all business contemplated
     by this Agreement to be conducted by the Servicer in any state in which a
     Mortgaged Property is located or is otherwise not required under applicable


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<PAGE>

     law to effect such qualification and, in any event, is in compliance with
     the doing business laws of any such state, to the extent necessary to
     ensure its ability to enforce each Mortgage Loan, to service the Mortgage
     Loans in accordance with the terms of this Agreement and to perform any of
     its other obligations under this Agreement in accordance with the terms
     hereof.

          (ii) The Servicer has the power and authority to service each Mortgage
     Loan, and to execute, deliver and perform, and to enter into and consummate
     the transactions contemplated by this Agreement and has duly authorized by
     all necessary corporate action on the part of the Servicer the execution,
     delivery and performance of this Agreement; and this Agreement, assuming
     the due authorization, execution and delivery hereof by the other parties
     hereto, constitutes a legal, valid and binding obligation of the Servicer,
     enforceable against the Servicer in accordance with its terms, except that
     (a) the enforceability hereof may be limited by bankruptcy, insolvency,
     moratorium, receivership and other similar laws relating to creditors'
     rights generally and (b) the remedy of specific performance and injunctive
     and other forms of equitable relief may be subject to equitable defenses
     and to the discretion of the court before which any proceeding therefor may
     be brought.

          (iii) The execution and delivery of this Agreement by the Servicer,
     the servicing of the Mortgage Loans under this Agreement, the consummation
     of any other of the transactions contemplated by this Agreement, and the
     fulfillment of or compliance with the terms hereof are in the ordinary
     course of business of the Servicer and will not (A) result in a material
     breach of any term or provision of the charter or by-laws of the Servicer
     or (B) materially conflict with, result in a material breach, violation or
     acceleration of, or result in a material default under, the terms of any
     other material agreement or instrument to which the Servicer is a party or
     by which it may be bound, or (C) constitute a material violation of any
     statute, order or regulation applicable to the Servicer of any court,
     regulatory body, administrative agency or governmental body having
     jurisdiction over the Servicer; and the Servicer is not in breach or
     violation of any material indenture or other material agreement or
     instrument, or in violation of any statute, order or regulation of any
     court, regulatory body, administrative agency or governmental body having
     jurisdiction over it which breach or violation may materially impair the
     Servicer's ability to perform or meet any of its obligations under this
     Agreement.

          (iv) The Servicer is an approved servicer of mortgage loans for Fannie
     Mae and is an approved servicer of mortgage loans for Freddie Mac.

           (v) No litigation is pending or, to the best of the Servicer's
     knowledge, threatened, against the Servicer that would materially and
     adversely affect the execution, delivery or enforceability of this
     Agreement or the ability of the Servicer to service the Mortgage Loans or
     to perform any of its other obligations under this Agreement in accordance
     with the terms hereof.

          (vi) No consent, approval, authorization or order of any court or
     governmental agency or body is required for the execution, delivery and
     performance by the Servicer of, or compliance by the Servicer with, this
     Agreement or the consummation of the transactions contemplated hereby, or
     if any such consent, approval, authorization or order is required, the
     Servicer has obtained the same.

          (vii) The Servicer will fully furnish (for the period it services the
     Mortgage Loans), in accordance with the Fair Credit Reporting Act and its
     implementing regulations, accurate and complete information (e.g.,
     favorable and unfavorable) on its borrower credit files to Equifax,
     Experian and Trans Union Credit Information Company on a monthly basis.


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     SECTION 2.05. Substitutions and Repurchases of Mortgage Loans Which Are Not
"Qualified Mortgages".

     Upon discovery by the Depositor, the Servicer or the Trustee that any
Mortgage Loan does not constitute a "qualified mortgage" within the meaning of
section 860G(a)(3) of the Code, the party discovering such fact shall promptly
(and in any event within five (5) Business Days of discovery) give written
notice thereof to the other parties. In connection therewith, the Depositor
shall, at the Depositor's option, either (i) substitute, if the conditions in
Section 2.03(c) with respect to substitutions are satisfied, a Replacement
Mortgage Loan for the affected Mortgage Loan, or (ii) repurchase the affected
Mortgage Loan within ninety (90) days of such discovery in the same manner as it
would a Mortgage Loan for a breach of representation or warranty contained in
Section 2.03. The Trustee shall reconvey to the Depositor the Mortgage Loan to
be released pursuant hereto in the same manner, and on the same terms and
conditions, as it would a Mortgage Loan repurchased for breach of a
representation or warranty contained in Section 2.03.

     SECTION 2.06. Authentication and Delivery of Certificates.

     The Trustee acknowledges the transfer and assignment to it of the Trust
Fund and, concurrently with such transfer and assignment, the Trustee has caused
to be authenticated and delivered to or upon the order of the Depositor, in
exchange for the Mortgage Loans, Certificates duly authenticated by the
Authenticating Agent in authorized denominations evidencing ownership of the
entire Trust Fund. The Trustee agrees to hold the Trust Fund and exercise the
rights referred to above for the benefit of all present and future Holders of
the Certificates and to perform its duties set forth in this Agreement in
accordance with the provisions hereof.

     SECTION 2.07. REMIC Elections.

     (a) The Depositor hereby instructs and authorizes the Trustee to make an
appropriate election to treat each of the SWAP REMIC, the Lower Tier REMIC and
the Upper Tier REMIC as a REMIC. The Trustee shall sign the returns providing
for such elections and such other tax or information returns which are required
to be signed by the Trustee under applicable law. This Agreement shall be
construed so as to carry out the intention of the parties that each of the SWAP
REMIC, the Lower Tier REMIC and the Upper Tier REMIC be treated as a REMIC at
all times prior to the date on which the Trust Fund is terminated.

     (b) The Preliminary Statement sets forth the designations and "latest
possible maturity date" for federal income tax purposes of all interests created
hereby. The "Startup Day," as defined in Section 860G(a)(9) of the Code, for
purposes of the REMIC Provisions shall be the Closing Date. Each REMIC's fiscal
year shall be the calendar year.

     The SWAP REMIC shall consist of all of the assets of the Trust Fund, other
than (i) amounts distributable to the Class P Certificates pursuant to Section
4.04(b)(i) hereof, (ii) the interests issued by the SWAP REMIC and the interests
issued by the Lower Tier REMIC, (iii) the grantor trusts described in Section
2.07 hereof, (iv) each Corridor Contract and the Corridor Contract Account and
(v) the Swap Agreement and the Supplemental Interest Trust. The SWAP REMIC shall
issue the SWAP REMIC Regular Interests, which shall be designated as regular
interests of such REMIC, and shall issue the Class SWR Interest, which shall be
designated as the sole class of residual interest in the SWAP REMIC. Each of the
SWAP REMIC Regular Interests shall have the characteristics set forth in the
Preliminary Statement and this Section 2.07.


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     The Lower Tier REMIC shall consist of the SWAP REMIC Regular Interests. The
Lower Tier REMIC shall issue the Lower Tier REMIC Regular Interests, which shall
be designated as regular interests of such REMIC and shall issue the Class LTR
Interest, which shall be designated as the sole class of residual interest in
the Lower Tier REMIC. Each of the Lower Tier REMIC Regular Interests shall have
the characteristics set forth in its definition and the Preliminary Statement.

     The assets of the Upper Tier REMIC shall be the Lower Tier REMIC Regular
Interests. The REMIC Regular Interests shall be designated as the regular
interests in the Upper Tier REMIC and the Residual Interest shall be designated
as the sole class of residual interest in the Upper Tier REMIC. For federal
income tax purposes, the pass-through rate on each REMIC Regular Interest (other
than the Uncertificated Class C Interest and the Class UT-IO Interest) and on
the sole class of residual interest in the Upper Tier REMIC shall be subject to
a cap equal to the Upper Tier REMIC Net WAC Cap.

     The beneficial ownership of the Class SWR Interest, the Class LTR Interest
and the Residual Interest shall be represented by the Class R Certificate. The
Class SWR Interest and the Class LTR Interest shall not have a principal balance
or bear interest.

     (c) The "tax matters person" with respect to each REMIC for purposes of the
REMIC Provisions shall be the beneficial owner of the Class R Certificate;
provided, however, that the Holder of the Class R Certificate, by its acceptance
thereof, irrevocably appoints the Trustee as its agent and attorney-in-fact to
act as "tax matters person" with respect to each such REMIC for purposes of the
REMIC Provisions. If there is more than one beneficial owner of the Class R
Certificate, the "tax matters person" shall be the Person with the greatest
percentage interest in the Class R Certificate and, if there is more than one
such Person, shall be determined under Treasury regulation Section 1.860F-4(d)
and Treasury regulation Section 301.6231(a)(7)-1.

     (d) (i) It is intended that the rights of the Class A Certificates, Class R
Certificate, Class M Certificates and Class B Certificates to receive payments
in respect of Excess Interest shall be treated as a right in interest rate cap
contracts written by the Class C Certificateholders in favor of the holders of
the Class A Certificates, Class R Certificate, Class M Certificates and Class B
Certificates, and such shall be accounted for as property held separate and
apart from the regular interests in the Upper Tier REMIC held by the holders of
the Class A Certificates, Class M Certificates and Class B Certificates and the
residual interest in the Upper Tier REMIC held by the holder of the Class R
Certificate. This provision is intended to satisfy the requirements of Treasury
Regulations Section 1.860G-2(i) for the treatment of property rights coupled
with REMIC interests to be separately respected and shall be interpreted
consistently with such regulation. On each Distribution Date, to the extent that
any of the Class A Certificates, Class R Certificate, Class M Certificates and
Class B Certificates receive payments in respect of Excess Interest, such
amounts, to the extent not derived from payments on the Corridor Contracts or
the Swap Agreement, will be treated as distributed by the Upper Tier REMIC to
the Class C Certificates pro rata in payment of the amounts specified in Section
4.04(f) and then paid to the relevant Class of Certificates pursuant to the
related interest rate cap agreement.

          (ii) It is intended that the beneficial owners of the Certificates
(other than the Class P and Class C Certificates) shall be treated as having
entered into a notional principal contract with respect to the beneficial owners
of the Class C Certificates. Pursuant to each such notional principal contract,
all beneficial owners of each Class of Certificates (other than the Class P and
Class C Certificates) shall be treated as having agreed to pay, on each
Distribution Date, to the beneficial owners of the Class C Certificates an
aggregate amount equal to the excess, if any, of (i) the amount payable on such
Distribution Date on the Corresponding REMIC Regular Interest of such Class of
Certificates over (ii) the amount payable on such Class of Certificates on such
Distribution Date (such excess, a "Class Payment Shortfall"). A Class Payment
Shortfall shall be allocated to each Class of Certificates to the extent that


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interest accrued on such Class for the related Accrual Period at the
Pass-Through Rate for a Class, computed by substituting "Upper Tier REMIC Net
WAC Cap" for the Available Funds Cap set forth in the definition thereof,
exceeds the amount of interest accrued on such Certificate at the Pass-Through
Rate (without such substitution) for the related Accrual Period, and a Class
Payment Shortfall payable from principal collections shall be allocated to the
most subordinate Class of Certificates with an outstanding principal balance to
the extent of such balance.

     (e) The parties intend that the portion of the Trust Fund consisting of the
Uncertificated Class C Interest, the uncertificated Class UT-IO Interest, the
rights to receive payments deemed made by the Class A, Class R, Class M and
Class B Certificates in respect of notional principal contracts described in
Section 2.07(d)(ii), the Corridor Contract Account, the Corridor Contracts, the
Supplemental Interest Trust that holds the Swap Agreement and the obligation of
the holders of the Class C Certificates to pay amounts in respect of Excess
Interest to the holders of the Class A Certificates, Class R Certificate, Class
M Certificates and Class B Certificates shall be treated as a "grantor trust"
under the Code, for the benefit of the holders of the Class C Certificates, and
the provisions hereof shall be interpreted consistently with this intention. In
furtherance of such intention, the Trustee shall (i) furnish or cause to be
furnished to the holders of the Class C Certificates information regarding their
allocable share, if any, of the income with respect to such grantor trust, (ii)
file or cause to be filed with the Internal Revenue Service Form 1041 (together
with any necessary attachments) and such other forms as may be applicable and
(iii) comply with such information reporting obligations with respect to
payments from such grantor trust to the holders of Class A Certificates, Class R
Certificate, Class M Certificates, Class B Certificates and Class C Certificates
as may be applicable under the Code.

     (f) The parties intend that the portion of the Trust Fund consisting of the
right to receive the payments distributable to the Class P Certificates pursuant
to Section 4.04(b)(i) hereof shall be treated as a "grantor trust" under the
Code, for the benefit of the holders of the Class P Certificates, and the
provisions hereof shall be interpreted consistently with this intention. In
furtherance of such intention, the Trustee shall (i) furnish or cause to be
furnished to the holders of the Class P Certificates information regarding their
allocable share of the income with respect to such grantor trust and (ii) file
or cause to be filed with the Internal Revenue Service Form 1041 (together with
any necessary attachments) and such other forms as may be applicable.

     (g) The parties intend that amounts paid to the Swap Counterparty under the
Swap Agreement shall be deemed for federal income tax purposes to be paid by the
Class C Certificates first, out of funds deemed received in respect of the Class
UT-IO Interest, second, out of funds deemed received in respect of the
Uncertificated Class C Interest and third, out of funds deemed received in
respect of notional principal contracts described in Section 2.07(d)(ii), and
the provisions hereof shall be interpreted consistently with this intention. On
each Distribution Date, to the extent that amounts paid to the Swap Counterparty
are deemed paid out of funds received in respect of the Uncertificated Class C
Interest, such amounts will be treated as distributed by the Upper Tier REMIC to
the Class C Certificates pro rata in payment of the amounts specified in Section
4.04(f) and then paid to the Swap Counterparty pursuant to the Swap Agreement.

          The Supplemental Interest Trust shall be an "outside reserve fund" for
federal income tax purposes and not an asset of any REMIC. Furthermore, the
Holders of the Class C Certificates shall be the beneficial owners of the
Supplemental Interest Trust for all federal income tax purposes, and shall be
taxable on all income earned thereon.

     (h) All payments of principal and interest at the Net Mortgage Rate on each
of the Mortgage Loans (other than amounts distributable to the Class P
Certificates pursuant to Section 4.04(b)(i) hereof)


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received by the SWAP REMIC with respect to the Mortgage Loans shall be paid to
the SWAP REMIC Regular Interests until the principal balance of all such
interests have been reduced to zero and any losses allocated to such interests
have been reimbursed. Any available funds remaining in the SWAP REMIC on a
Distribution Date after distributions to the SWAP REMIC Regular Interests shall
be distributed to the Class R Certificate on account of the Class SWR Interest.
On each Distribution Date, the Trustee shall distribute the aggregate Interest
Funds (net of expenses (other than any Net Swap Payment or Swap Termination
Payment required to be made to the Swap Counterparty) and payments to the Class
P Certificates) with respect to each of the SWAP REMIC Regular Interests based
on the interest rates for each such SWAP REMIC Regular Interest. On each
Distribution Date, the Trustee