Commenced
Commenced means, with respect to the definition of new source in section 111(2) of the Act, that an owner or operator has undertaken a continuous program of construction or modification or that an owner or operator has entered into a contractual obligation to undertake and complete, within a reasonable time, a continuous program of construction or modification.
Source
40 CFR § 60.2
Scoping language
The terms used in this part are defined in the Act or in this section as follows: