NY -- Standard&Poor's CreditWire 7/28/97 -- Standard&Poor's today has assigned its double-`A'-minus rating to Florida State Board of Regents' university system improvement revenue refunding bonds series 1997 dated July 15, 1997 due July 1, 2016, issued for Florida State University System. The rating reflects: -- A total enrollment of more than 207,000 and pledged revenues derived from these students; -- The breadth of the system, which currently encompasses nine campuses and programs ranging from undergraduate to doctoral; -- Strong state support; and -- A low debt burden. The bonds are secured on parity with series 1991 and 1993 (both AMBAC insured) and series 1997 (MBIA insured) by two fees that students must pay upon enrollment. As