Integrated Services Digital Network (ISDN) - Signalling System No. 7; ISDN User Part (ISUP) version 3 interactions with the Intelligent Network Application Part (INAP) - Part 4: Abstract Test Suite (ATS) and partial Protocol Implementation eXtra Information for Testing (PIXIT) proforma specification (Endorsement of the English version EN 301070-4 V 1.1.2 (2000-11) as German Standard)