Unit operating hour
Unit operating hour means a clock hour during which any fuel is combusted in the affected unit. If the unit combusts fuel for the entire clock hour, it is considered to be a full unit operating hour. If the unit combusts fuel for only part of the clock hour, it is considered to be a partial unit operating hour.
Source
40 CFR § 60.331
Scoping language
As used in this subpart, all terms not defined herein shall have the meaning given them in the Act and in subpart A of this part.