This Recommendation provides supplementary information on the usage of the service-related information elements (B‑BC, AAL parameters, B-HLI, B-LLI, N-BC, N-HLC, N-LLC) for individual B-ISDN services. It considers the services as they are specified for public B-ISDN. It does not specify additional codings required to support services by private networks. This Recommendation is Part 1 of Recommendation Q.2939. The coding for the parameters which are defined in Recommendation Q.2931 (1996) are specified in this part, while the coding for the additional traffic parameters which are defined in Recommendation Q.2961 (1996) are expected to be specified in the subsequent publication of additional parts of Recommendation Q.2939.