The ratings on the Pennsylvania Higher Education Assistance Agency's $75 million education loan revenue bonds series 1988C are based on a financial guaranty insurance policy provided by Ambac Assurance Corp. (Ambac; 'AAA' insurer financial strength rating) that guarantees payment of scheduled principal and interest. The short-term rating reflects the likelihood of payment of purchase price based on the availability of the liquidity facility provided by First Union National Bank. The short-term rating will expire on Feb. 1, 2004, upon the mandatory tender before the expiration of the liquidity facility. Although the rating is dependent on Standard&Poor's rating of Ambac's insurer financial strength, the underlying transaction is of investment-grade quality, as illustrated by the following: The overcollateralization that opens