EPA is revising the format of 40 CFR part 52 for materials submitted by states that are incorporated by reference into their respective state implementation plans (SIPs). This format revision will primarily affect the ``Identification of plan'' sections assigned to each subpart (i.e., state or territory) of 40 CFR part 52, as well as the format of the SIP materials that will be available for public inspection at the Office of the Federal Register, the Air and Radiation Docket and Information Center located in Waterside Mall, Washington, D.C., and the originating Regional Offices. The revised format will; better serve to help the public in determining the applicable state provisions, rules and regulations that comprise the respective Federally-enforceable SIP's; streamline the format of the documents that will be available for public inspection at the above-mentioned locations; streamline the IBR review process followed by the Office of the Federal Register in reviewing state material for incorporation by reference into 40 CFR part 52; and assure continued compliance with the provisions of the Clean Air Act, which requires EPA to periodically publish comprehensive SIP documents for each state. The sections of 40 CFR part 52 pertaining to provisions promulgated by EPA or state- submitted materials not subject to IBR review remain unchanged.