This Document specifies methods, apparatus, and calculations which are used in conjunction with Performance Test Codes to determine quantitatively, the gaseous constituents of exhausts resulting from stationary combustion sources. The gases covered by this Document are oxygen, carbon dioxide, carbon monoxide, nitrogen, sulfur dioxide, sulfur trioxide, nitric oxide, nitrogen dioxide, hydrogen sulfide, and hydrocarbons. Stationary combustion sources include steam generators, gas turbines, internal combustion engines, incinerators, etc. Included are instrumental methods as well as (normally, wet chemical) methods. The instrumental methods include instruments used for non-continuous or continuous sampling using extractive samples and in-situ type instruments that require no sampling system.