Business TeleCommunications (BTC) - 64 kbit/s digital unrestricted leased line with octet integrity (D64U) - Terminal equipment interface; English version ETS 300290:1994/A1:1995
Private Integrated Services Network (PISN) - Mapping functions for the employment of 64 kbit/s circuit mode connections with 16 kbit/s sub-multiplexing; English version EN 301039 V 1.1.1 (1997-12)— 18 стр.
Access and Terminal (AT) - 64 kbit/s digital unrestricted leased line with octet integrity (D64U) - Terminal equipment interface (Endorsement of the English version EN 300290 V 1.2.1 (2001-07) as German Standard)— 1 стр.
