Defines the Information Retrieval Application Service and specifies the Information Retrieval Application Protocol. The service definition describes services that support capabilities within an aplication; the services in turn are supported by the Z39.50 protocol. The protocol specification includes the definition of the protocol information, the rules for exchanging this information, and the conformance requirements to be met by implementation of this protocol. It is intended for systems supporting information retrieval services and for organizations such as information services, universities, libraries and union catalogue centres. This Standard addresses the connection-oriented, program-to-program communications. It does not address interchange of the information with terminals or via other physical means. This Standard is identical with and has been reproduced from ISO 23950:1998