49 CFR § 543.4 - Definitions.
(a) Statutory terms. All terms defined in sections 2, 601, and 605 of the Motor Vehicle Information and Cost Savings Act are used in accordance with their statutory meanings unless otherwise defined in paragraph (b) of this section.
(b) Other definitions.
Accessory mode means the ignition switch setting in which certain electrical systems (such as the radio and power windows) can be operated without the operation of the vehicle's propulsion engine.
Immobilizer means a device that, when activated, is intended to prevent a motor vehicle from being powered by its own propulsion system.
Line or car line means a name which a manufacturer applies to a group of motor vehicles of the same make which have the same body or chassis, or otherwise are similar in construction or design. A “line” may, for example, include 2-door, 4-door, station wagon, and hatchback vehicles of the same make.
NHTSA means the National Highway Traffic Safety Administration.