This part of the seven part European Telecommunication Standard ETS 300 133@ describes the general aspects of the European Radio Message System (ERMES). It comprises an abstract of each part of the ETS along with a general description of: - the objectives of the system; - the services and facilities; - a description of the elements and their functions. A complete vocabulary for all parts of ETS 300 133 is given@ together with a list of abbreviations and acronyms. Normative references which are quoted in each part of ETS 300 133 are gathered together and listed in Annex A (informative) of this part.