ETSI TR 101 731-2000 接入和终端(AT).公共通信网的数字接入.根据1999/5/EC导则发布的接口规范.数字接口的描述指南(版本1.1.1)
Access and Terminals (AT); Digital Access to the Public Telecommunications Network; Publication of Interface Specification under Directive 1999/5/EC; Guidelines for Describing Digital Interfaces (V1.1.1)