This Recommendation | International Standard defines in an abstract way the externally visible service provided by the OS1 Transport Layer in terms of
- the primitive actions and events of the service;
- the parameter data associated with each primitive action and event;
- the relationship between, and the valid sequences of, these actions and events.
The service defined in this Recommendation | International Standard is that which is provided by all OS1 Transport Protocols (in conjunction with the Network Service) and which may be used by any OS1 Session Protocol.