ABT averaging, banking, and trading.

AECD auxiliary emission control device.

AESS automatic engine stop/start

AF adjustment factor (see § 1033.530).

CFR Code of Federal Regulations.

CH₄ methane.

CO carbon monoxide.

CO₂ carbon dioxide.

EPA Environmental Protection Agency.

FEL Family Emission Limit.

g/bhp-hr grams per brake horsepower-hour.

HC hydrocarbon.

hp horsepower.

LPG liquefied petroleum gas.

LSD low sulfur diesel.

MW megawatt.

N₂O nitrous oxide.

NIST National Institute of Standards and Technology.

NMHC nonmethane hydrocarbons.

NO_X oxides of nitrogen.

PM particulate matter.

rpm revolutions per minute.

SAE Society of Automotive Engineers.

SCR selective catalytic reduction.

SEA Selective Enforcement Audit.

THC total hydrocarbon.

THCE total hydrocarbon equivalent.

UL useful life.

ULSD ultra low sulfur diesel.

U.S. United States.

U.S.C. United States Code.