Okla. Admin. Code § 252:100-33-1.1
The following terms, when used in this subchapter, shall have the following meaning, unless the context clearly indicates otherwise:
"New fuel-burning equipment" means any fuel-burning equipment that was not in being on February 14, 1972, or any existing fuel-burning equipment that was altered, replaced, or rebuilt after February 14, 1972, resulting in increased emissions of nitrogen oxides with the following exceptions.
(A) New fuel-burning equipment for gas turbines means any gas turbine that was not in being on July 1, 1977, or any existing gas turbine that was altered, replaced, or rebuilt after July 1, 1977, resulting in increased emissions of nitrogen oxides; and
(B) New fuel-burning equipment for direct-fired processes means any direct-fired fuel-burning equipment or processes that were not in being on July 1, 1977, or any existing direct-fired fuel-burning equipment or processes that were altered, replaced, or rebuilt after July 1, 1977, resulting in increased emissions of nitrogen oxides.
"Solid fossil fuel" means solid fossil fuel such as coal and any solid fuel derived from naturally occurring coal or petroleum.
"Three-hour average" means the arithmetic average of sampling results or continuous emission monitoring data from three contiguous one-hour periods.
Okla. Admin. Code § 252:100-33-1.1