The following symbols, acronyms, and abbreviations apply to this part: $ U.S. dollars.CFR Code of Federal Regulations.disp engine displacement.EPA Environmental Protection Agency.kW kilowatt.L/cyl liters per cylinder.NARA National Archives and Records Administration.NOX Oxides of nitrogen.SAE Society of Automotive Engineers.SEA selective enforcement audit.U.S. United States.U.S.C. United States Code.