This Recommendation provides the concepts, definitions and profile of the minimal upper layer facilities necessary to support basic connection-oriented communications applications. These facilities consist of a subset of the facilities defined in the ACSE, and the Presentation and Session service definitions. A basic communications application simply requires the ability to open and close communications with a peer and to send and receive messages with that peer. It is expected that a large portion of OSI applications will be satisfied by such minimal functionality.

This is one of a series of Recommendations to support the minimal OSI functions in the upper layers. It is technically aligned with ISO/IEC ISP 11188-3.