Summary

Amendment 2 to Recommendation ITU-T Z.120 addresses the problem of possible applications of message sequence charts (MSCs). These application domains are not explicitly defined in the main part of this Recommendation, which leaves ground for the following interpretation that MSCs can be used in almost any context, without restriction. This is not the case, and this appendix clarifies several interpretation issues related to the verification and implementability of MSCs, and shows some syntactic requirements needed for each of these applications.

Amendment 2 cancels and replaces Amendment 1 (2008) to Recommendation ITU‑T Z.120 (2004).