Broadband Integrated Services Digital Network (B-ISDN) - Signalling System No. 7; B-ISDN User Part (B-ISUP) - Part 4: Look-ahead without state change for the network node interface [ITU-T Recommendation Q.2724.1 (1996)] (Endorsement of the English version EN 301029-4 V 1.2.1 (1998-04) as German standard)