pro rata amount. In a bullet-payment structure, the investor receives the entire amount in one distribution. Since there is no assurance that the entire amount can be paid in one lump sum, the procedure is for the trustee to place principal monthly into an account that generates sufficient interest to make periodic interest payments and to accumulate the principal to be repaid. The time period over which the principal is accumulated is called the accumulation period. There are two basic types of bullet payments (i.e., soft versus hard) that differ according to steps taken by the issuer to insure investors will receive full payment of principal on the maturity date.3 With a soft bullet payment, investors rely exclusively on the underlying portfolios payment speed for full payment of the principal at maturity. So, while the principal funding account is structured to have sufficient funds to pay the entire principal on the bonds expected matu- rity date, there is no guarantee. Conversely, with a hard bullet payment, the issuer purchases a maturity guarantee to ensure there will be suffi- cient funds to pay the entire principal on the expected maturity date. There are provisions in credit card receivable-backed securities that require early amortization of the principal if certain events occur. Such provisions, which are referred to as early amortization or rapid amorti- zation provisions, are included to safeguard the credit quality of the issue. The only way that the cash flows can be altered is by the trigger- ing of the early amortization provision. When early amortization occurs, the credit card tranches are retired sequentially (i.e., first the AAA bond, then the AA rated bond, and so on). Exhibit 10.3 presents a Bloomberg screen displaying a credit card receivable structure. The deal consists of two securities (A and B) issued from the Citibank Credit Card Master Trust I, Series 1999-7. Exhibit 10.4 presents a Bloomberg Security Description screen for the senior tranche A. This tranche is rated Aaa and carries a 6.65% coupon rate paid semiannu- ally. Note also that next to WAL (weighted average life) in the center of the screen is an "n.a." or not applicable. This is so because credit card receivables are non-amortizing assets so the concept of a prepayment does not apply. Hence, WAL does not apply. The amortization structure used is   3Robert Karr, Greg Richter, R. J. Shook, and Lireen Tsai, "Credit-Card Receiv- ables" Chapter 3 in Anand K. Bhattacharya and Frank J. Fabozzi (eds.), Asset- Backed Securities (New Hope, PA: Frank J. Fabozzi Associates, 1996).     a soft bullet with the principal expected to be paid in a single payment on November 15, 2004. Exhibit 10.5 presents a Bloomberg Security Descrip- tion screen for the subordinated tranche B. Note that B is rated A2 by Moodys and carries a higher coupon rate of 6.9%.