The corrections and updates affect provisions of parts of 40 CFR 51, 60, and 63. This rule was originally proposed on January 26, 2018 and is being adopted with a few changes from the original proposal. The action makes corrections and revisions to source test methods, performance specifications (PS), quality assurance/quality control (QA/QC) procedures, and testing regulations. The corrections and revisions consist of typographical errors, updates to testing procedures, and the addition of alternative equipment and methods the Agency has deemed acceptable to use. One change will impact Table 6 of subpart DDDDD of 40 CFR 63. This change allows the use of EPA SW-846-7471B (for liquid samples) in addition to EPA SW-846-7470A for measuring mercury to allow flexibility. This rule becomes effective on January 14, 2019.