IEC 60169-7 Amd.1 Ed. 1.0 b:1993
Amendment 1 – Radio-frequency connectors. Part 7: R.F. coaxial connectors with inner diameter of outer conductor 9.5 mm (0.374 in) with bayonet lock – Characteristic impedance 50 ohms (Type C)
Amendment by International Electrotechnical Commission, 09/06/1993