Effective date means:
(1) With regard to an emission standard established under this part, the date of promulgation in the Federal Register of such standard; or
(2) With regard to an alternative emission limitation or equivalent emission limitation determined by the Administrator (or a State with an approved permit program), the date that the alternative emission limitation or equivalent emission limitation becomes effective according to the provisions of this part.
40 CFR § 63.2
The terms used in this part are defined in the Act or in this section as follows: