This Recommendation describes the DSS 2 generic identifier transport capability. This capability allows the transport through the B-ISDN of identifiers required and used by various distributed applications. This Recommendation is applicable to equipment, supporting DSS 2 signalling capabilities as defined, in particular, in Recommendations Q.2931 [1] and Q.2971 [2], attached at either side of a TB reference point or coincident SB and TB reference point when used as an access to the public B-ISDN. This DSS 2 signalling capability allows to carry identifiers between a call originating entity (e. g. a calling user) and an addressed entity (e. g. a remote user, or an interworking unit or a high layer function node addressed by the calling user). The identifiers are transmitted unchanged through the network and they are used by various distributed applications. This signalling capability is a means of end-to-end signalling using identifiers having a specific purpose which the network can optionally access but not change. In some cases the network may create an identifier on behalf of the user or at its request.