Communicating Presentation Information in Internet Messages: The Content-Disposition Header

This memo provides a mechanism whereby messages conforming to the [RFC 1521] ("MIME") specification can convey presentational information. It specifies a new "Content-Disposition" header, optional and valid for any [RFC 1521] entity ("message" or "body part"). Two values for this header are described in this memo; one for the ordinary linear presentation of the body part, and another to facilitate the use of mail to transfer files. It is expected that more values will be defined in the future, and procedures are defined for extending this set of values.