MIL MIL-S-19500/533D

SEMICONDUCTOR DEVICE, DIODE, SILICON, ZENER, VOLTAGE REGULATOR, SOLID GLASS NONCAVITY CONSTRUCTION, TYPES 1N6309 THROUGH 1N6355; 1N6309US THROUGH 1N6336US; PLUS C AND D TOLERANCE SUFFIX (SUPERSEDING MIL-S-19500/533C) (S/S BY MIL-PRF-19500/533E)
standard by Military Specifications and Standards, 09/20/1993