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Re: AW: XHTML 2.0 and hreflang and type

From: Lachlan Hunt <lhunt07@postoffice.csu.edu.au>
Date: Thu, 13 Nov 2003 17:29:26 +1100
Message-ID: <3FB324C6.5020808@postoffice.csu.edu.au>
To: W3C HTML List <www-html@w3.org>

Ernest Cline wrote:

>... if an author wishes to indicate that a png file is preferable to a gif (As is usually the case. :)) then instead of:
><span type="image/png, image/gif; q=0.1" src="../images/115">
> Image #115
>One could use:
><span type="image/png" src="../images/115.png">
> <span type="image/gif" src="../images/115.gif">
>   Image#115
> </span>
  Although the above example should work, The reason for making the type 
attribute a list of media types, rather than only a single type is 
because it is better to be able to use the same URI and recieve a 
different version based on what can be understood by the UA.

  In the example given in section 6.6 of the current working draft 
(2003-05-06) [1]:
    <p src="w3c-logo" type="image/png, image/jpeg;q=0.2">W3C logo</p>
the URI is specified without a file extension, though the actual file 
delivered by the server will be either w3c-logo.png or w3c-logo.jpg.

  This uses content negotiation with the server, rather than specifying 
which particular file version is needed within the page.  (The document 
"Cool URIs don't change" [2], as well as some other various documents on 
W3, explain this concept much better than I have)

>I see no reason why type should be changed from being advisory as it is in
>HTML4 to being proscriptive as it is in the XHTML2 draft.
  Type is only meant to be advice about what content types are 
available, to allow the UA to build the HTTP request header 
appropriately.  It just allows multiple content-types to be specified 
which will be quite useful for some authors.

[2] http://www.w3.org/Provider/Style/URI
Received on Thursday, 13 November 2003 01:29:27 UTC

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