W3C home > Mailing lists > Public > www-html@w3.org > November 2003

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
></span>
>
>One could use:
><span type="image/png" src="../images/115.png">
> <span type="image/gif" src="../images/115.gif">
>   Image#115
> </span>
></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.

[1] 
http://www.w3.org/TR/2003/WD-xhtml2-20030506/mod-attribute-collections.html#col_Embedding
[2] http://www.w3.org/Provider/Style/URI
Received on Thursday, 13 November 2003 01:29:27 UTC

This archive was generated by hypermail 2.3.1 : Wednesday, 5 February 2014 23:40:09 UTC