It is necessary to have throughout the international network types of coaxial pairs having the same electrical characteristics, in order to enable transmission systems to operate on any cable meeting the specifications of this Recommendation. The use of these pairs is defined by Tables 1/G.623 and 2/G.623 given in the introduction to § 6.2.
ITU-T G.623-1993 Referenced Document
ITU-T G.623 CHARACTERISTICS OF 2.6/9.5 mm COAXIAL CABLE PAIRS
ITU-T G.623-1993 history
1993ITU-T G.623-1993 CHARACTERISTICS OF 2.6/9.5 mm COAXIAL CABLE PAIRS