### Question
How is the term commenced defined?


### Answer
The term **commenced** is defined in *40 CFR § 52.01* as the following:

> that an owner or operator has undertaken a continuous program of construction or modification.

#### Citation:
  - *40 CFR § 52.01*
  - Heading: **PART 52—APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS > Subpart A—General Provisions > SUBCHAPTER C—AIR PROGRAMS (CONTINUED) > SUBCHAPTER C—AIR PROGRAMS (CONTINUED)**

