Re: MIME variables

[davidk@lysator.liu.se (David Kågedal)]

Lars Magne Ingebrigtsen <larsi@gnus.org> writes:

> Hrvoje Niksic <hniksic@srce.hr> writes:
> 
> > > text/x-patch would perhaps be better?  That would mean that they are
> > > human-readable, but not plain.
> > 
> > Probably.  Yes.
> 
> I'm just off for bed, but does the MIME RFC's say anything in
> particular about doing stuff like text/x-patch?  I know that it's
> common to do application/x-whatever, but I don't really recall seeing
> many x-whatevers as subtypes of the text type...

Looking at RFC 2045, I see tht the BNF grammar allows subtypes of the
x-* variety. Scanning quickly through the document, I see no other
restrictions.

RFC 2046 has the following to say about text/*:

    (1)   text -- textual information.  The subtype "plain" in
          particular indicates plain text containing no
          formatting commands or directives of any sort. Plain
          text is intended to be displayed "as-is". No special
          software is required to get the full meaning of the
          text, aside from support for the indicated character
          set. Other subtypes are to be used for enriched text in
          forms where application software may enhance the
          appearance of the text, but such software must not be
          required in order to get the general idea of the
          content.  Possible subtypes of "text" thus include any
          word processor format that can be read without
          resorting to software that understands the format.  In
          particular, formats that employ embeddded binary
          formatting information are not considered directly
          readable. A very simple and portable subtype,
          "richtext", was defined in RFC 1341, with a further
          revision in RFC 1896 under the name "enriched".
[...]

   The canonical form of any MIME "text" subtype MUST always represent a
   line break as a CRLF sequence.  Similarly, any occurrence of CRLF in
   MIME "text" MUST represent a line break.  Use of CR and LF outside of
   line break sequences is also forbidden.

   This rule applies regardless of format or character set or sets
   involved.

[...]
4.1.4.  Unrecognized Subtypes

   Unrecognized subtypes of "text" should be treated as subtype "plain"
   as long as the MIME implementation knows how to handle the charset.
   Unrecognized subtypes which also specify an unrecognized charset
   should be treated as "application/octet- stream".


-- 
David Kågedal        <davidk@lysator.liu.se> http://www.lysator.liu.se/~davidk/