This standard describes a system of nomenclature that provides designations for glass bulbs used as the envelopes for electric lamps. This system is shown in customary (inch-based) units and SI (metric) units. The nomenclature system is intended for application with bulbs that originate both as parts and as stock. As a part@ a bulb is assembled directly into finished lamps without major alterations. As stock@ a bulb may be re-worked or altered during lamp assembly@ while maintaining its basic identifying characteristics.