This Recommendation/International Standard specifies
(a) procedures for the connectionless-mode transmission of data and protocol control information from one transport entity to one peer transport entity.
(b) the encoding of the transport-protocol-data-units used for the transmission of data and control information;
(c) procedures for the correct interpretation of transport protocol control information; and
(d) the functional requirements for implementations claiming conformance to this Recommendation/International Standard.
The procedures are defined in terms of
(a) the interactions among peer transport entities through the exchange of transport-protocol-data-units;
(b) the interactions between a transport entity and a transport service user through the exchange of transport service primitives; and
(c) the interaction between a transport entity and a network service provider through the exchange of network service primitives.
This Recommendation/International Standard specifies the connectionless-mode transport protocol and provides the PICS Proforma in compliance with the relevant requirements, and in accordance with the relevant guideline, given in CCITT Rec. X.291 / ISO/IEC 9646-2. The protocol for providing the connection-mode transport service is specified in ITU-T Rec. X.224 / ISO/IEC 8073.