This part specifies procedures for a single protocol for the transfer of data and control information from one application entity to a peer application entity in the MMS context, the means of selecting the services to be used by the application entities while communicating in the MMS context, the structure of the MMS Protocol Data Units used for the transfer of data and control information. The procedures are applicable to instances of communication between systems which support MMS within the application layer of the OSI Reference Model, and which require the ability to interconnect in an open systems interconnection environment.