and, to the extent necessary, proceeds of Ginnie Mae's guaranty of the Ginnie Mae Certificates. As a result, defaults experienced on the Mortgage Loans will accelerate the distribution of principal of the Securities. Under  certain  circumstances,  the  Trustee  has  the  option  to  purchase  the  Trust  Assets, thereby  effecting  early  retirement  of  the  Securities.  See  "Description  of  the  Securities – Termination" in this Supplement. Investors  in  the  Group  1  Securities  are  urged  to  review  the  discussion  under  "Risk Factors – The rate of principal payments on the underlying SMBS securities will directly affect the rate of principal payments on the group 1 securities" in this Supplement. Accretion Directed Classes Classes F, FD, PA, PB, PC, S, SD, VC and ZA are Accretion Directed Classes. The related Accrual Amount will be applied to making principal distributions on those Classes as described in this Supplement. Classes IP and SI are Notional Classes whose Class Notional Balances are determined by reference to the Class Principal Balances of Classes PA and PC, in the case of Class IP, and Class F, in the case of Class SI. Each of the Accretion Directed Classes has the AD designation in the suffix position, rather than the prefix position, in its class principal type because it does not have principal payment stability  through  the  applicable  pricing  prepayment  assumption.  Although  the  Accretion Directed Classes are entitled to receive payments from the related Accrual Amounts, they do not have principal payment stability through any prepayment rate significantly higher than 0% PSA. Securities that Receive Principal on the Basis of Schedules As described in this Supplement, each PAC and TAC Class will receive principal payments in accordance with a schedule calculated on the basis of, among other things, a Structuring Range or Rate. 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  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. The TAC Classes have no Effective Rate. Based on the Modeling Assumptions, the initial Effective Ranges for the PAC Classes are as follows: Initial Effective Ranges PAC Classes FD, PA, PB, PC and SD (in the aggregate)................ 126% PSA through 239% PSA FA, FB, FC, FJ, OA, OB, OC and OJ (in the aggregate) ...................................................................... 125% PSA through 250% PSA S-18