Exhibit A Underlying Certificates Trust Asset Group Issuer Series Class Issue Date CUSIP Number Interest Rate Interest Type(1) Final Distribution Date Principal Type(1) Original Principal Balance of Class Underlying Certificate Factor(2) Principal Balance in the Trust Percentage of Class in Trust Approximate Weighted Average Coupon of Mortgage Loans Approximate Weighted Average Remaining Term to Maturity of Mortgage Loans (in months) Approximate Weighted Average Loan Age of Mortgage Loans (in months) Ginnie Mae I or II 2 Ginnie Mae   2007-035 TD June 28, 2007 38375KQM7 6.0% FIX August 2036 PAC I $30,022,020 1.00000000 $10,022,020 33.3822307759% 6.422% 351 8 II 2 Ginnie Mae   2007-049 ND August 30, 2007 38375LAN0 6.0 FIX January 2037 PAC I 31,587,670 1.00000000 31,587,670 100.0000000000% 6.412% 353 6 II 2 Ginnie Mae   2007-049   NE(3)    August 30, 2007 38375LCE8 6.0 FIX August 2037 PAC I 20,681,518 1.00000000 20,681,518 100.0000000000% 6.412% 353 6 II (1)  As defined under "Class Types" in Appendix I to the Base Offering Circular. (2)  Underlying Certificate Factors are as of December 2007. (3)  MX Class A-1