The following symbols, acronyms, and abbreviations apply to this part:ABT Averaging, banking, and trading.AECD Auxiliary emission control device.CFR Code of Federal Regulations.CH4 methane.CO carbon monoxide.CO2 carbon dioxide.EPA Environmental Protection Agency.FEL Family Emission Limit.g gram.HC hydrocarbon.hr hour.kPa kilopascals.kW kilowatt.m meter.N2O nitrous oxide.NARA National Archives and Records Administration.NMHC nonmethane hydrocarbons.NOX oxides of nitrogen (NO and NO2).NTE not-to-exceedpsig pounds per square inch of gauge pressure.RPM revolutions per minute.SAE Society of Automotive Engineers.THC total hydrocarbon.THCE total hydrocarbon equivalent.U.S.C. United States Code.