RFC 1590 (rfc1590) - Page 3 of 7

Media Type Registration Procedure

RFC 1590           Media Type Registration Procedure          March 1994


   The Media Type registrations will be posted in the anonymous FTP
   directory "ftp.isi.edu:in-notes/media-types" and the Media Type will
   be listed in the periodically issued "Assigned Numbers" RFC [2].  The
   Media Type description may be published as an Informational RFC by
   sending it to "" (please follow the instructions to
   RFC authors [3]).

3. Clarifications On Specific Issues

3.1 MIME Requirements for a Limited Number of Content-Types

   Issue:  In the asynchronous mail environment, where information on
   the capabilities of the remote mail agent is not available to the
   sender, maximum interoperability is attained by restricting the
   number of content-types used to those "common" content-types expected
   to be widely implemented.  This was asserted as a reason to limit the
   number of possible content-types and resulted in a registration
   process with a significant hurdle and delay for those registering
   content-types.

   Comment:  The need for "common" content-types formats does not
   require limiting the registration of new content-types.  This
   restriction may, in fact, hinder interoperability by causing separate
   registration authorities for specific applications which may register
   values in conflict with or otherwise incompatible with each other.
   If a limited set of content-types recommended for a particular
   application, that should be asserted by a separate applicability
   statement specific for the application and/or environment.

3.2 Requirements for a Published Specification

   Issue:  Content-Type registration requires an RFC specifying the data
   format or a reference to a published specification of the data
   stream.  This requirement may be overly restrictive for the use of
   content-type registration for file attachments and distribution
   because a public specification may not be available for a number of
   widely used and exchanged objects.

   Comment:  MIME required the documentation of a specific content-type
   to allow the unambiguous identification of a defined type.  This
   intent is met by the identification of a particular software package
   and version when registering the content-type and is allowed for
   registration.  The appropriateness of using a Media Type with an
   unavailable specification should not be an issue in the registration.







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