Securities that Receive Principal on the Basis of Schedules As described in this Supplement, each PAC and  Scheduled  Class will receive principal payments in accordance with a schedule calculated on the basis of, among other things, a Structuring Range. See "Terms Sheet – Scheduled Principal Balances." However, whether any such Class will adhere to its schedule and receive "Scheduled Payments" on a Distribution Date will largely depend on the level of prepayments experienced by the related Mortgage Loans. Each PAC and Scheduled Class exhibits an Effective Range of constant prepayment rates at which such Class will receive Scheduled Payments. That range may differ from the Structuring Range used to create the related principal balance schedule. Based on the Modeling Assump- tions, the initial Effective Ranges for the PAC and Scheduled Classes are as follows: PAC I Classes Initial Effective Range EL, LA, LB, LC, LD, LE and LH (in the aggregate) 100% PSA through 250% PSA PAC II Class Initial Effective Range JX .......................................................................................... 131% PSA through 262% PSA Scheduled Classes Initial Effective Ranges EA and FA (in the aggregate)  ...................................... 189% PSA through 253% PSA EC and FB (in the aggregate) ...................................... 189% PSA through 253% PSA •   The principal payment stability of the PAC I Classes  will be supported by the related PAC II and Support Classes and Components. •   The principal payment stability of the PAC II Class  will be supported by the related Support Classes and Components. •   The principal payment stability of the Scheduled Classes will be supported by the related Support Classes. If all of the Classes and Components supporting a given Class are retired before the Class being supported is retired, the outstanding Class will no longer have an Effective Range and will become more sensitive to prepayments on the related Mortgage Loans. There is no assurance that the related Mortgage Loans will have the characteristics assumed in the Modeling Assumptions, which were used to determine the initial Effective Ranges. If the initial Effective Ranges were calculated using the actual characteristics of the related Mortgage Loans, the initial Effective Ranges could differ from those shown in the above tables. Therefore, even if the Mortgage Loans were to prepay at a constant rate within the initial Effective Range shown for any Class in the above tables, that Class could fail to receive Scheduled Payments. Moreover, the Mortgage Loans will not prepay at any constant rate. Non-constant prepay- ment rates can cause any PAC or Scheduled Class not to receive Scheduled Payments, even if prepayment rates remain within the initial Effective Range for that Class. Further, the 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. S-21