This European Telecommunication Standard (ETS) specifies the method for specification of basic and supplementary services provided by a Private Telecommunications Network (PTN) to users of terminal equipment attached to it. It applies to any other PTN-related standard@ such as: - stage 1 and stage 2 specifications of basic and supplementary services; - specifications of basic and supplementary service signalling protocols@ at any relevant PTN reference point@ in the context of any scenarios for the interconnection of Private Telecommunications Network Exchanges (PTNXs) and in the context of interworking with other networks. This ETS applies to Private Telecommunications Networks (PTNs). Informative references are given in Annex A.