Re: Inconsistency between IETF and W3C: XML fragments and media types

[Chris Lilley <chris@xxxxxx>]

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