NY -- Standard&Poor's CreditWire 3/18/98 -- Standard&Poor's today assigned its triple-'A' rating to Naperville, Ill.'s G.O. bonds series 1998 dated April, 1, 1998 due Dec. 1, 1999-2012. Additionally, Standard&Poor's affirmed its triple-'A' rating on the city's outstanding G.O. bonds. The rating reflects: -- A large, well-diversified, and steadily growing tax base; -- Very high wealth indicators reflecting the high-tech employment base as well as the city's convenient highway and rail access to employment in the greater Chicago-area; -- Extremely strong fiscal management and excellent financial performance; and -- Above-average debt levels that are manageable given the city's wealth levels and tax base growth. Naperville is located about 30 miles west of Chicago. Population, estimated