ETSI EN 300 356-33-2003 综合业务数字网(ISDN).7号信令系统(SS7).国际接口的ISDN用户部分(ISUP)版本4.第33部分:抽象测试套件(ATS)和部分协议额外测试信息实现(PIXIT)形式规范
Integrated Service Digital Network (ISDN); Signalling System No.7 (SS7); ISDN User Part (ISUP) version 4 for the international interface; Part 33: Abstract Test Suite (ATS) and partial Protocol Implementation eXtra Information for Testing (PIXIT) proforma