This standard (Part III) specifies the dimensions, constructional details and the requirements for the RF flexible coaxial cables having type designation 50-7-1.
IS 5801 Pt.3-1970 history
1971IS 5801 Pt.3-1970 Specification for Flexible Coaxial Radio Frequency Cables with a Characteristic Impedance of 50Ω Part III Cable Types 50-7-1