Broadband Integrated Services Digital Network (B-ISDN) - Digital Subscriber Signalling System No. two (DSS2) protocol; connection characteristics; negotiation during call/connection establishment phase - Part 6: Abstract Test Suite (ATS) and partial Protocol Implementation eXtra Information for Testing (PIXIT) proforma specification for the network (Endorsement of the English version EN 301067-6 V 1.1.3 (1999-11) as German Standard)