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 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 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-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:
Class A Non-PO Optimal Amount As to any Distribution Date, the sum for such Distribution Date of (i) the Class A Interest Accrual Amount, (ii) the Aggregate Class A Unpaid Interest Shortfall and (iii) the Class A Non-PO Optimal Principal Amount.