EN 301 061-4 : 1.1.4

INTEGRATED SVCS DIGITAL NETWK (ISDN); DIGITAL SUBSCRIBER SIGNALLING SYSTEM NO.ONE (DSS1) PROTOCOL; GENERIC FUNCTIONAL PROTOCOL FOR THE SUPPORT OF SUPPLEMENTARY SERVICES AT THE "B" SVC ENTRY POINT FOR VIRTUAL PRIVATE NETWK (VPN) APPLICATIONS; PART 4: ABSTRACT TEST SUITE (ATS) AND PARTIAL PROTOCOL IMPLEMENTATION EXTRA INFO FOR TESTING (PIXIT) PROFORMA SPECIFICATION FOR THE USER

European Telecommunications Standards Institute