This International Standard defines in an abstract way the externally visible service provided by the OSI Transport Layer in terms of
a) the primitive actions and events of the service;
b) the parameter data associated with each primitive ac-tion and event;
c) the relationship between, and the valid sequences of the actions and events.
The service defined in this International Standard is that which is provided by all OSI Transport Protocols (in conjunction with the Network Service) and which may be used by any OSI Ses-sion Protocol.
This International Standard does not specify individual im-plementations or products, nor does it constrain the implemen-tation of entities and interfaces within a computer system. There is, therefore no conformance to this International Standard.