olemus
ISO/IEC 2382:
kahesuunalise andmeedastuse kanalite paar, võib sisaldada lõppseadmeid
= pair of associated transmission channels that provides a means of two-way data transmission



ülevaateid
https://www.teracomtraining.com/tutorials/teracom-tutorial-data-circuit-model.htm
https://en.wikipedia.org/wiki/Data_circuit-terminating_equipment
https://www.icao.int/SAM/Documents/2010/REDDIGRTO2010/05%2006.%20Data%20transmssion%20interfaces%20data%20transmission%20means.pdf