## Related to *Class A Non-PO Optimal Amount*

**Class A Non-PO Optimal Principal Amount** As to any Distribution Date, an amount equal to the sum, as to each Outstanding Mortgage Loan, of the product of (x) the Non-PO Fraction with respect to such Mortgage Loan, and (y) the sum of:

**Class A-PO Optimal Principal Amount** As to any Distribution Date, an amount equal to the sum of (I) the sum as to each Outstanding Mortgage Loan, of the product of (x) the PO Fraction with respect to such Mortgage Loan and (y) the sum of:

**Class A Non-PO Principal Distribution Amount** As to any Distribution Date, the aggregate amount distributed in respect of the Class A Certificates pursuant to Paragraph third clause (A) of Section 4.01(a).

**Class A-X Notional Amount** With respect to any Distribution Date and the Class A-X Certificates, the product of (x) the aggregate Stated Principal Balance, as of the second preceding Due Date (after giving effect to Scheduled Payments for that Due Date, whether or not received), or for the initial Distribution Date, as of the Cut-off Date, of the Premium Rate Mortgage Loans with respect to Loan Group 2 and Loan Group 4 (excluding any Special Payoff Mortgage Loans); and (y) a fraction, the numerator of which is the weighted average of the related Stripped Interest Rates for the Premium Rate Mortgage Loans with respect to Loan Group 2 and Loan Group 4 as of such date (excluding any Special Payoff Mortgage Loans) and the denominator of which is 6.00%.

**Class X-B Notional Amount** As of any date of determination, the aggregate of the Certificate Balances of the Class A-S, Class B and Class C Certificates.

**Class X-A Notional Amount** As of any date of determination, the aggregate of the Certificate Balances of the Class A Certificates (other than the Class A-S Certificates).

**Class B-1 Optimal Principal Amount** As to any Distribution Date, an amount equal to the sum of (I) the sum, as to each Outstanding Mortgage Loan, of the product of (x) the Non-PO Fraction with respect to such Mortgage Loan and (y) the sum of:

**Class PEZ Component B Principal Amount** The product of the Class B-PEZ Percentage Interest and the Certificate Balance of the Class B Regular Interest.

**Class X-1 Notional Amount** means, with respect to any Distribution Date, the aggregate of the Certificate Balances of the Principal Balance Certificates as of the close of business on the preceding Distribution Date.

**Class B-4 Optimal Principal Amount** As to any Distribution Date, an amount equal to the sum of (I) the sum, as to each Outstanding Mortgage Loan, of the product of (x) the Non-PO Fraction with respect to such Mortgage Loan and (y) the sum of:

**Class B-2 Optimal Principal Amount** As to any Distribution Date, an amount equal to the sum of (I) the sum, as to each Outstanding Mortgage Loan, of the product of (x) the Non-PO Fraction with respect to such Mortgage Loan and (y) the sum of:

**Class X-2 Notional Amount** (i) With respect to any Distribution Date on or prior to the Distribution Date in [__________], the sum of the then Component Notional Amounts of Component XA-1-2, Component XA-1-3, Component XA-1-4, Component XA-1A-2, Component XA-1A-3, Component XA-1A-4, Component XA-1A-5, Component XA-1A-6, Component XA-1A-7, Component XA-1A-8, Component XA-1A-9, Component XA-1A-10, Component XA-1A-11, Component XA-1A-12, Component XA-1A-13, Component XA-1A-14, Component XA-1A-15, Component XA-2-1, Component XA-2-2, Component XA-2-3, Component XA-2-4, Component XA-2-5, Component XA-2-6, Component XA-2FL-1, Component XA-2FL-2, Component XA-2FL-3, Component XA-2FL-4, Component XA-2FL-5, Component XA-2FL-6, Component XA-3-1, Component XA-3-2, Component XA-4-1, Component XA-4-2, Component XA-4-3, Component XA-4-4, Component XA-4-5, Component XA-4-6, Component XA-SB-1, Component XA-SB-2, Component XA-SB-3, Component XA-SB-4, Component XA-SB-5, Component XA-SB-6, Component XA-M, Component XA-J, Component XB, Component XC, Component XD-1, Component XD-2, Component XD-3, Component XE-1, Component XE-2, Component XE-3, Component XF-1, Component XF-2, Component XF-3, Component XG-1, Component XG-2, Component XH-1, Component XH-2, Component XH-3, Component XJ, Component XK-1, Component XK-2 and Component XL.

**Class X-F Notional Amount** As of any date of determination, the Certificate Balance of the Class F Certificates.

**Class A-2 Monthly Interest** means (i) for the initial Distribution Date, $[_______________], and (ii) for any Distribution Date thereafter, one-twelfth of the product of (A) the Class A-2 Rate and (B) the outstanding principal balance of the Class A-2 Notes as of the preceding Distribution Date (after giving effect to all payments of principal made to the Holders of the Class A-2 Notes on or before such preceding Distribution Date).

**Class B-6 Optimal Principal Amount** As to any Distribution Date, an amount equal to the sum of (I) the sum, as to each Outstanding Mortgage Loan, of the product of (x) the Non-PO Fraction with respect to such Mortgage Loan and (y) the sum of:

**Class A-3 Monthly Interest** means (i) for the initial Distribution Date, $[ ], and (ii) for any Distribution Date thereafter, one-twelfth of the product of (A) the Class A-3 Rate and (B) the outstanding principal balance of the Class A-3 Notes as of the preceding Distribution Date (after giving effect to all payments of principal made to the Holders of the Class A-3 Notes on or before such preceding Distribution Date).

**Class A-4 Monthly Interest** means (i) for the initial Distribution Date, $[ ], and (ii) for any Distribution Date thereafter, one-twelfth of the product of (A) the Class A-4 Rate and (B) the outstanding principal balance of the Class A-4 Notes as of the preceding Distribution Date (after giving effect to all payments of principal made to the Holders of the Class A-4 Notes on or before such preceding Distribution Date).

**Class A-1 Monthly Interest** means, for any Distribution Date, the product of (A) the actual number of days elapsed during the period from and including the Closing Date (in the case of the first Distribution Date) or from and including the preceding Distribution Date to but excluding such Distribution Date divided by 360, (B) the Class A-1 Rate and (C) the outstanding principal balance of the Class A-1 Notes as of the Closing Date (in the case of the first Distribution Date) or as of the preceding Distribution Date (after giving effect to all payments of principal made to the Holders of the Class A-1 Notes on or before such preceding Distribution Date).

**Class B Optimal Principal Amount** Any of the Class B-1 Optimal Principal Amount, Class B-2 Optimal Principal Amount, Class B-3 Optimal Principal Amount, Class B-4 Optimal Principal Amount, Class B-5 Optimal Principal Amount or Class B-6 Optimal Principal Amount.

**Collateral Minimum Monthly Interest** shall have the meaning specified in subsection 4.02(c).

**Class X-C Notional Amount** As of any date of determination, the then Class X Component Notional Amount of the Class X-C Component.

**Class X-D Notional Amount** As of any date of determination, the Certificate Balance of the Class D Certificates.

**Class A-4 Interest Distributable Amount** means the amount of interest accrued during the related Interest Period (calculated on the basis of a 360 day year consisting of twelve 30 day months) on the Class A‑4 Principal Balance as of the immediately preceding Payment Date (after giving effect to payments of principal made on such immediately preceding Payment Date) at the Class A‑4 Rate or, in the case of the first Payment Date, on the Class A‑4 Initial Principal Balance.

**Class A Monthly Interest** shall have the meaning specified in subsection 4.02(a).

**Class B-5 Optimal Principal Amount** As to any Distribution Date, an amount equal to the sum of (I) the sum, as to each Outstanding Mortgage Loan, of the product of (x) the Non-PO Fraction with respect to such Mortgage Loan and (y) the sum of: