.INTERNATIONAL TELECOMMUNICATION UNIONCCITTG.703THE INTERNATIONALTELEGRAPH AND TELEPHONECONSULTATIVE COMMITTEEGENERAL ASPECTS OF DIGITALTRANSMISSION SYSTEMSTERMINAL EQUIPMENTSPHYSICAL/ELECTRICAL CHARACTERISTICSOF HIERARCHICAL DIGITAL INTERFACESRecommendation G.703Geneva, 1991FOREWORDThe CCITT (the International Telegraph and Telephone Consultative Committee) is the permanent organ of the International