Provides for the testing of gas turbines supplied with gaseous or liquid fuels (or solid fuels converted to liquid or gas prior to entrance to the gas turbine). Tests of gas turbines with emission control and/or power augmentation devices, such as injection fluids and inlet air treatment, are included. It may be applied to gas turbines in combined cycle plants or with other heat recovery systems. This Code provides for comparative (back to back) tests designed to verify performance differentials of the gas turbine, primarily for testing before and after modifications, up rates, or overhauls.