Standard&Poor's Ratings Services raised it rating to 'AA-' from 'A+' on Irvine, Calif.'s 1993 certificates of participation (COPs), based on continued solid tax base and revenue growth and the city's proven financial strength. The rating reflects: The city's strong general creditworthiness; and A covenant to budget and appropriate lease payments. The general creditworthiness of the city reflects: Its participation in the strong and diverse Orange County MSA; Above-average wealth and income indicators, coupled with low unemployment rates; and Strong financial performance, demonstrated by a continuously large unrestricted general fund balance. These strengths are offset by a high overall debt burden on both a per capita and market value basis. The City of Irvine (population 180,803) is in southern