Historical
NEMA ANSI C78.391:2004
Electric lamps - characteristics of subminiature lamps of t1 and ti-3/4 shapes
Sets forth the physical and electrical characteristics of those groups of subminiature incandescent lamps with T1 and T1_ bulb shapes. Lamps with various base or termination configurations are included.
NEMA: National Electrical Manufacturers Association [nema]