The following acronyms and abbreviations apply to part 90. AECD--Auxiliary emission control deviceASME--American Society of Mechanical EngineersASTM--American Society for Testing and MaterialsCAA--Clean Air ActCAAA--Clean Air Act Amendments of 1990CLD--chemiluminescent detectorCO--Carbon monoxideCO2--Carbon dioxideEPA--Environmental Protection AgencyFTP--Federal Test Procedureg/kW-hr--grams per kilowatt hourHC--hydrocarbonsHCLD--heated chemiluminescent detectorHFID--heated flame ionization detectorICI--independent Commercial ImporterNDIR--non-dispersive infrared analyzerNIST--National Institute for Standards and TestingNO--Nitric oxideNO2--Nitrogen dioxideNOX--Oxides of nitrogenO2--OxygenOEM--original equipment manufacturerPMD--paramagnetic detectorSAE--Society of Automotive EngineersSEA--Selective Enforcement AuditingSI--spark-ignitionU.S.C.--United States CodeVOC--Volatile organic compoundsZROD--zirconiumdioxide sensor