This European Telecommunication Standard (ETS) provides a detailed spe cification for interworking between the A-interface protocol and the M obile Application Part for handling of supplementary services. The MAP interfaces of interest are the B-, C-, D- and E-interfaces. The A-, C-, D- and E-interfaces are physical interfaces while the B-in terface is an internal interface defined for modelling purposes. Infor mation relating to the modelling interface is not normative in this ET S. Supplementary service signalling may be passed by the MSC/VLR between the A- and E-interfaces after inter-MSC handover. This procedure is tr ansparent as far as supplementary services are concerned therefore int erworking concerning this process is not described in this ETS. Clause 2 describes general procedures for interworking between the A- and D- physical interfaces. Clause 3 describes the general procedures for the SS version negotiati on. Clause 4 describes the mapping of layer 3 radio path messages with Tra nsaction Capabilities (TC) transaction sublayer messages for interwork ing between the A- and D- physical interfaces. Clause 5 describes specific interworking procedures for all interfaces relating to call related SS activity. Clause 6 describes specific interworking procedures for all interfaces relating to call independent SS activity. Clause 6 also covers the in terworking between the MAP User (see GSM 09.02) and the SS handling fu nctions of the network entities (see GSM 04.10 and 04.80). Reference is made to the following Technical Specifications: - GSM 02.04 and GSM 02.8x and GSM 02.9x-series, for definition of supplementary services; - GSM 03.11, GSM 03.8x and GSM 03.9x-series, for technical realization of supplementary services; - GSM 04.10p GSM 04.80, GSM 04.8x and GSM 04.9x-series, for radio path signalling procedures for supplementary services; - GSM 09.02 (MAP).