Historical
ANSI C78.21-2011 (R2016)
Electric Lamps - PAR and R Shapes
Covers lamps with clear, frosted and lens end bulbs, clear and prescription lenses, and with various reflector coatings. Lamps described in this standard may contain incandescent filament or a tungsten halogen inner bulb.
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NEMA: National Electrical Manufacturers Association [nema]