ITU-T Q.2630.2 Annex D

This new annex contains a comprehensive definition of the AAL type 2 signalling procedures in SDL. The data structures required for the SDL definition as well as the data structure for the messages in the main part of the Recommendation are specified in ASN.1. Although, the SDL definitions contain more detail than the prose definition in clause 8, the definitions in clause 8 take precedence. Nevertheless, this new annex clearly indicates which part of the procedures specified in clause 8 are left to individual implementations and which part of the procedures must be implemented precisely for conformance with this Recommendation. In addition, this new annex demonstrates that semi-formal definitions for signalling protocols are possible.