ietf-xml-mime
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Re: Inconsistency between IETF and W3C: XML fragments and media types

1999-11-24 22:24:04


Dan Connolly wrote:

My recollection is that type="..." is advisory: it helps user agents
optimize for the case that they don't know the relevant media type,
so they can skip fetching the thing. So it would be odd for it
to be mandatory. But sure enough! it is:

=======
The following pseudo attributes are defined

href CDATA #REQUIRED
type CDATA #REQUIRED
title CDATA #IMPLIED
media CDATA #IMPLIED
charset CDATA #IMPLIED
alternate (yes|no) "no"

The semantics of the pseudo-attributes are exactly as with <LINK
REL="stylesheet"> in HTML 4.0
=======

I wonder why it's mandatory.

Because typically, CSS processors cannot deal with XSL stylesheets and
XSL processors cannot deal with CSS stylesheets, and avioding
downloading the thing if it is not a type you can process is highly
desirable.


Anyway.. regarding the semantics... the advisory stuff seems to have
been
lost somewhere:

========
http://www.w3.org/TR/1998/REC-html40-19980424/struct/links.html#adef-type-A

type = content-type [CI]
    When present, this attribute specifies the content type of a piece
of
    content, for example, the result of dereferencing a URI. Content
types
    are defined in [MIMETYPES].
========

The same text occurs at
http://www.w3.org/TR/1999/PR-html40-19990824/struct/links.html#adef-type-A

Hmm... perhaps I can get this cleared up before HTML 4.01 becomes a
recommendation.

Anyway... the type="text/xml" in the XSLT spec example is saying:
"the stylesheet I'm pointing to is written in XML; 

It would be more useful to say it is written in XS:L (is thatwhat you
meant?)

This is a case where it might be useful to have a specific MIME
type for XSL(T), 

There was one, last I looked.

so that you could say:

        "the stylesheet I'm pointing to is written in XSL; if you don't
        grok XSL, don't bother fetching it."

Exactly.


"   draft-murata-00: Application/xml-dtd, a naming convention (*/*-xml),
   and examples (application/mathml-xml, application/xsl-xml,
   application/rdf-xml, and image/svg-xml) are added."

I don't care for that idea.

Because ....

Have you been following the IETF/W3C/IMC joint mailing list about MIME
types for XML? That is where this -xml stuff originated from.

I *do* like image/svg-xml, actually. It certainly better than either
image/svg or application/xml in terms of saying what the SVG file
contains.

--
Chris