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 FRENCH-1993 Referenced Document
ITU-T J.18 Crosstalk in Sound-Programme Circuits Set up on Carrier Systems - Line Transmission of Non-Telephone Signals - Transmission of Sound-Programme and Television Signals (Study Group XV) 3 pp