Defines the message store abstract-service. This abstract-service is provided by the message store access-protocol in conjunction with the message transfer system abstract-service, together with the remote operations service element (ROSE) services. This Standard is identical with and reproduced from ISO/IEC 10021-5:1990, and includes Technical Corrigendum 1:1991, Technical Corrigendum 2:1991 and Technical Corrigendum 3:1992.