Integrated Services Digital Network (ISDN) - Signalling System No. 7; Support of Virtual Private Network (VPN) applications with Private network Q reference point Signalling System number 1 (PSS1) information flows - Part 1: Protocol specification (ITU-T-Recommendations Q.765.1 and Q.699.1, modified) (Endorsement of the English version EN 301062-1 V 1.2.2 (1998-07) as German Standard)