PDF Standards IEC 61169-8 Ed. 1.0 en:2007
Radio-frequency connectors – Part 8: Sectional specification – RF coaxial connectors with inner diameter of outer conductor 6,5 mm (0,256 in) with bayonet lock – Characteristic impedance 50 ¿¿ (type BNC)
standard by International Electrotechnical Commission, 02/16/2007