Historical
NEMA ANSI C78.1407:2004
For electric lamps - electric lamps - condenser-reflector, four-pin prefocus-base projection lamps - dimensions
Specifies the dimensions essential to the interchangeability of condenser-reflector lamps having four-pin prefocus bases, T12 or T14 bulbs, and used in 8mm motion-picture projectors.
NEMA: National Electrical Manufacturers Association [nema]