ietf-822
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Re: Character-set header (was Re: Minutes of the Atlanta 822ext meeting)

1991-09-10 14:51:28
Nice attempt!  I like what Greg has written (especially putting
PostScript under image!).  A couple of things:

TEXT PLUS: Requires a text oriented display only. 
      (I understand this to include LaTeX, .nroff, and richtext,

We should be careful here.  I agree about an nroff-restricted set of
troff, and richtext, because both explicitly restrict themselves to
text.  I'm less sure about LaTeX.  Formats like SGML can contain almost
arbitrary data, encoded as text, so I'd (continue to :-) argue that they
can't fall under this category.  Similarly for ATK format, and other
mixed-media formats.  Yes, they are represented with text, and
knowledgeable wizards may be able to make useful changes using only a
text editor, but there is no guarantee that the text is not just an
encoding of an audio track or bitmap or whatever.

Perhaps restricted versions of those formats could be defined (similar
to the nroff restriction on troff), and these restricted versions could
be regarded as 'text-plus' formats.

VIDEO:  Required a bit-mapped display and a lot of disk space and a
      lot of CPU and maybe even signal processing hardware. It
      implies nothing about being revisble.

Not necessarily.  The video could be supplied via a non-workstation
channel (analog signals to a nearby monitor, for instance, is how we are
doing it here at PARC).  I actually think that the video domain is so
poorly defined at the moment, that we can't say anything useful about
the VIDEO type -- for actual use, most video formats will wind up under
APPLICATION.

A general comment:

Future multi-media mailers are increasingly going to send messages that
are mixed in type, supported by formats that are either designed
explicitly or extended to support the mixed media.  It would be nice if
these were all sent as MULTIPART, but they won't be:  there will be one
body (one document) of a particular format, with various kinds of
"stuff" mixed into it.  If we really want the type field to support the
kinds of information that Greg outlines, there will have to be some way
to provide a list of types, e.g.

    Content-type:  TEXT,AUDIO,IMAGE,APPLICATION;BBN-SLATE

Bill




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