1. (a) is surplus, quantifiable, permanent, and enforceable; and

2. (b) will result or resulted from a physical change in, or a change in the method of operation of an emission source subject to Part 201 of this Title:

   1. (1) is quantified as the difference between baseline actual emissions and the subsequent potential to emit; and
   2. (2) is approved in accordance with the provisions of this Part; or
3. (c) will result or resulted from a physical change in, or a change in the method of operation of an emission source not subject to Part 201 of this Title, and is approved in accordance with the provisions of section 231-10.7 of this Subpart.

Any decrease in emissions of a regulated NSR contaminant, in tpy, which: