The abbreviations of this section apply to all subparts of this part and have the following meanings: AECD--Auxiliary emission control device.API--American Petroleum Institute.ASTM--American Society for Testing and Materials. C--Degrees Celsius.CH4--Methane.CI--Compression ignition.CO--Carbon monoxide.CO2--Carbon dioxide.disp.--volumetric displacement of an engine cylinder.EGR--Exhaust gas recirculation.EP--End point.EPA--Environmental Protection Agency.FEL--Family emission limit.ft--foot or feet.FTP--Federal Test Procedure.g--gram(s).g/kW-hr--Grams per kilowatt hour.gal--U.S. gallon.h--hour(s).HC--hydrocarbon.Hg--Mercury.hp--horsepower.ICI--Independent Commercial Importer.in--inch(es).K--Kelvin.kg--kilogram(s).km--kilometer(s).kPa--kilopascal(s).kW--kilowatt.L/cyl--liters per cylinder.m--meter(s).max--maximum.mg--milligram(s).min--minute.ml--milliliter(s).mm--millimeter.NIST--National Institute for Standards and Testing.NMHC--Non-methane hydrocarbons.NTIS--National Technical Information Service.NO--nitric oxide.NO2--nitrogen dioxide.NOX--oxides of nitrogen.No.--number.O2--oxygen.pct--percent.PM--particulate matter.PMM--post-manufacture marinizer.ppm--parts per million by volume.ppmC--parts per million, carbon.rpm--revolutions per minute.s--second(s).SAE--Society of Automotive Engineers.SEA--Selective Enforcement Auditing.SI--International system of units (i.e., metric).THC--Total hydrocarbon.THCE--Total hydrocarbon equivalent.U.S.--United States.U.S.C.--United States Code.vs--versus.W--watt(s).wt--weight. [64 FR 73331, Dec. 29, 1999, as amended at 74 FR 56374, Oct. 30, 2009]