Most lighting devices on motor vehicles today are required by law and are essential to operation on public roadways. Additionally, most lighting devices have replaceable light sources (bulbs). To assure field replacement, it is important that bulb types employed be readily available in normal service channels. This document attempts to define the physical, electrical, and photometric characteristics necessary to achieve a proper replacement for popular types of bulbs. Some of the design characteristics in this document are listed solely for the sake of standardization and are not intended to describe the performance of lighting devices (lamp assemblies) on the vehicle.