Effective Range for any PAC  or Scheduled  Class can narrow, shift over time or cease to exist depending on the actual characteristics of the related Mortgage Loans. If the related Mortgage Loans prepay at rates that are generally below the Effective Range for any PAC or Scheduled Class, the amount available to pay principal on the Securities may be insufficient to produce Scheduled Payments on such related PAC or Scheduled Class, if any, and its Weighted Average Life may be extended, perhaps significantly. If the related Mortgage Loans prepay at rates that are generally above the Effective Range for any PAC or Scheduled Class, its supporting Classes may be retired earlier than that PAC or Scheduled Class, and its Weighted Average Life may be shortened, perhaps significantly. Assumability Each Mortgage Loan may be assumed, subject to HUD review and approval, upon the sale of the related Mortgaged Property. See "Yield, Maturity and Prepayment Considerations – Assumability of Government Loans" in the Base Offering Circular. Final Distribution Date The Final Distribution Date for each Class, which is set forth on the front cover of this Supplement  or  on  Schedule  I  to  this  Supplement,  is  the  latest  date  on  which  the  related Class Principal Balance or Class Notional Balance will be reduced to zero. •   The actual retirement of any Class may occur earlier than its Final Distribution Date. •   According to the terms of the Ginnie Mae Guaranty, Ginnie Mae will guarantee payment in full of the Class Principal Balance of each Class of Securities no later than its Final Distribution Date. Modeling Assumptions Unless otherwise indicated, the tables that follow have been prepared on the basis of the characteristics of the Underlying Certificates, the priorities of distributions on the Underlying Certificates and the following assumptions (the "Modeling Assumptions"), among others: 1.  The Mortgage Loans underlying the Group 1 Trust Assets have the assumed characteris- tics shown under "Assumed Characteristics of the Mortgage Loans Underlying the Group 1 Trust Assets" in the Terms Sheet, except in the case of information set forth under the 0% PSA Prepayment Assumption Rate, for which each Mortgage Loan underlying a Group 1 Trust Asset is assumed to have an original and a remaining term to maturity of 360 months and a Mortgage Rate of 1.50% per annum higher than the related Certificate Rate. 2.  The  Mortgage  Loans  prepay  at  the  constant  percentages  of  PSA  (described  below) shown in the related table. 3.  Distributions  on  the  Securities  are  always  received  on  the  20th  day  of  the  month, whether or not a Business Day, commencing in September 2007. 4.  A termination of the Trust or the Underlying Trusts does not occur. 5.  The Closing Date for the Securities is August 30, 2007. 6.  No expenses or fees are paid by the Trust other than the Trustee Fee. 7.  Distributions  on  the  Underlying  Certificates  are  made  as  described  in  the  related Underlying Certificate Disclosure Documents. S-17