Integrated Services Digital Network (ISDN) - Outgoing Call Bearing (OCB) supplementary service; Digital Subscriber Signalling System No. one (DSS1) protocol - Part 6: Abstract Test Suite (ATS) and partial Protocol Implementation eXtra Information for Testing (PIXIT) proforma specification of the network (Endorsement of the English version EN 301001-6 V 1.1.4 (1999-11) as German standard)