Describes a set of mappings which will enable interworking between systems operating the CCITT X.400 (1988) Recommendations on Message Handling Systems / ISO IEC 10021 Message Oriented Text Interchange Systems (MOTIS( [CCITT/ISO88a], and systems using the RFC 822 mail protocol [Crocker82a] or protocols derived from RFC 822. Aims to maximize the services offered across the boundary, whilst not requiring unduly complex mappings. Specifies a mapping between two protocols.