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Re: Feedback for draft-nottingham-http-link-header-03

From: Julian Reschke <julian.reschke@gmx.de>
Date: Wed, 10 Dec 2008 10:28:11 +0100
Message-ID: <493F8BAB.8010708@gmx.de>
To: Mark Nottingham <mnot@mnot.net>
CC: "Roy T. Fielding" <fielding@gbiv.com>, HTTP Working Group <ietf-http-wg@w3.org>

Mark Nottingham wrote:
> ...
>       <t>HTML4 also has a "rev" parameter for links that allows a link's 
> relation to be reversed. The Link header
>         has a "rev" parameter to allow the expression of these links in 
> HTTP headers, but its use is not encouraged,
>         due to the confusion this mechanism causes as well as 
> conflicting interpretations among HTML versions.</t>
> ...

OK, it seems I'm missing something here. Could somebody explain to me, 
what the conflicting interpretations are, and which we prefer (and why?)?

HTML2 (<http://tools.ietf.org/html/rfc1866#section-5.7.3>):

     REL
             The REL attribute gives the relationship(s) described by
             the hyperlink. The value is a whitespace separated list
             of relationship names. The semantics of link
             relationships are not specified in this document.

     REV
             same as the REL attribute, but the semantics of the
             relationship are in the reverse direction. A link from A
             to B with REL="X" expresses the same relationship as a
             link from B to A with REV="X". An anchor may have both
             REL and REV attributes.

HTML4 (<http://www.w3.org/TR/html4/struct/links.html#rev-link>):

   12.3.1 Forward and reverse links

   The rel and rev attributes play complementary roles -- the rel
   attribute specifies a forward link and the rev attribute specifies a
   reverse link.

   Consider two documents A and B.

     Document A:       <LINK href="docB" rel="foo">

   Has exactly the same meaning as:

     Document B:       <LINK href="docA" rev="foo">

   Both attributes may be specified simultaneously.



Best regards, Julian
Received on Wednesday, 10 December 2008 09:28:57 GMT

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