District of Columbia's baseball park revenue bonds taxable series 2006A-1 and A-2, series 2006B-1, and series 2006B-2 (auction rate certificates) have been rated 'BBB'. The bonds are secured by various pledged revenues, but the ultimate security rests with the ballpark fee, a corporate gross receipts tax, that can be increased to cover any deficiencies or shortfalls in other dedicated revenues. The rating reflects: A narrow tax revenue pledge of the ballpark fee, levied on business owners that can be increased to cover deficiencies in other dedicated revenues; The cross-collateralization of the of the three series of bonds, (excluding the taxable series A-1) whereby excess revenues from the certain sources can be used to pay debt services; The incentive provided by