Standard&Poor's Ratings Services affirmed its 'A-' underlying rating (SPUR) on Burton Elementary School District, Calif.'s certificates of participation. The outlook is stable. The rating reflects our view of the district's: Primarily residential tax base and role as a bedroom community for Porterville, Very strong unreserved general fund balances, and Low overall debt burden. Partially offsetting these strengths is our view of: The district's concentration in the agriculture and agribusiness industries, The district's high unemployment, and A constrained state funding environment. Lease payments made by the district, as leasee, to the Local Facilities Finance Corp., a nonprofit public benefit corporation, as lessor, for the use of district facilities secure the lease revenue bonds. The district has covenanted to budget