Broadband Integrated Services Digital Network (B-ISDN) - Digital Subscriber Signalling System No. two (DSS2) protocol; Connection characteristics; Modification procedures for sustainable cell rate parameters - 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 301276-6 V 1.1.1 (2002-02) as German Standard)