28-1141. Definitions In this article, unless the context otherwise requires: 1. ' Envelope' means the outermost dimensions of a load or vehicle to include width, height and length and the weight of the vehicle or its load. 2. ' Envelope permit' means a permit issued by the department authorizing a person to transport property on the highways of this state pursuant to all applicable statutes and local ordinances and the terms listed on the permit. 3. ' Power unit' means a vehicle that propels itself or tows a trailer or combination of vehicles on the highways of this state.
Arizona Legal Code