Broadband Integrated Services Digital Network (B-ISDN) - Digital Subscriber Signalling System No. two (DSS2) protocol; B-ISDN user-network interface layer 3 specification for basic call/bearer control - Part 1: Protocol specification (ITU-T-Recommendation Q.2931 (1995), modified) (Endorsement of the English version EN 300443-1 V 2.0.1 (2001-03) as German standard)