This Recommendation | International Standard specifies: a) procedures for the connectionless transmission of data and protocol control information from one session entity to a peer session entity; b) the encoding of the session protocol data units used for the transmission of data and control information; c) procedures for the correct interpretation of session protocol control information; and d) the functional requirements for implementations claiming conformance to this Recommendation | International Standard. The procedures are defined in terms of: e) the interactions among peer session entities through the exchange of session protocol data units; f ) the interactions between a session entity and a session service user through the exchange of session service primitives; and g) the interactions between a session entity and a transport provider through the exchange of transport service primitives. This Recommendation | International Standard specifies a connectionless session protocol. A connection-oriented session protocol is specified in ITU-T Rec. X.225 | ISO/IEC 8327-1.