This action promulgates corrections and updates to regulations for source testing of emissions under various rules. This final rule includes corrections to typographical and technical errors, updates to outdated procedures, and revisions to add clarity and consistency with other monitoring requirements. The revisions will improve the quality of data but will not impose new substantive requirements on source owners or operators. This rule is effective on 30 May 2023. POC is Mrs. Lula H. Melton, Office of Air Quality Planning and Standards, Air Quality Assessment Division (E143-02), EPA, Research Triangle Park, NC 27711; tele: (919) 541-2910; email: melton.lula@epa.gov.(Federal Register 29 March 2023 [Rule] Pages 18396-18423)