-<DT><STRONG><A NAME="item_payby">payby - `CARD' (credit cards), `BILL' (billing), or `COMP' (free)</A></STRONG><DD>
-<DT><STRONG><A NAME="item_payinfo">payinfo - card number, P.O.#, or comp issuer (4-8 lowercase alphanumerics; think username)</A></STRONG><DD>
+<DT><STRONG><A NAME="item_payby">payby - `CARD' (credit cards), `BILL' (billing), `COMP' (free), or `PREPAY' (special billing type: applies a credit - see FS::prepay_credit and sets billing type to BILL)</A></STRONG><DD>
+<DT><STRONG><A NAME="item_payinfo">payinfo - card number, P.O., comp issuer (4-8 lowercase alphanumerics; think username) or prepayment identifier (see FS::prepay_credit)</A></STRONG><DD>