1 Scope ISO 8571-4 consists of four main sections: a) the basic protocol (in sections two and three), which supports the internal file service; b) the error recovery protocol (in section four), which supports the external file service. For each of these, ISO 8571-4 includes a formal statement of the nature of the automaton giving the necessary behaviour of each of the participating entities. It states: 1) the actions to be taken on receiving request and response primitives issued by a file service user; 2) the actions to be taken on receiving indication and confirm primitives issued by the Presentation Service provider; 3) the actions to be taken as a result of events within the local system. c) the definition (in section five) of the abstract syntax required to convey the file protocol control information. d) the conformance requirements to be met by implementors of this protocol (in section six). The scope of the File Protocol is limited to the interconnection of systems; it does not specify or restrict the possible implementation of interfaces within a computer system.