The rating on Illinois Development Finance Authority's (IDFA) bonds, issued for Chicago Board of Education (CBOE), reflects the security provided by an irrevocable intercept of general state aid to a trustee in amounts sufficient to meet debt service requirements. The IDFA will purchase local government securities from the obligor, the payments on which are then applied to service the Qualified Zone Academy Bonds (QZABs) issued by the IDFA. The QZABs are double-tax exempt and payable in a single principal maturity due Dec. 21, 2011. No interest payments are made; instead, bondholders receive credits to federal income taxes. Bondholders are protected from dilution by a provision requiring that general state aid measures at least 125% of maximum annual debt service requirements