X.400, one of the first OSI Application layer standards to be ratified, has generated considerable interest in the computer and telecommunications industry. Software vendors and network service providers are now marketing X.400‐based products. Message handling systems based on X.400 support interpersonal electronic mail services and also provide a generic mechanism for the exchange of information between computer systems. This ability to support information transfer between computer systems is the real contribution of X.400. Telecommunications based on this standard can be applied to library operations such as interlibrary loan, acquisitions and document delivery.