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Re: The range of the HTTP dereference function

From: Simon St.Laurent <simonstl@simonstl.com>
Date: 20 Mar 2002 22:04:59 -0500
To: "'www-tag'" <www-tag@w3.org>
Message-Id: <1016679900.890.5.camel@localhost.localdomain>
On Wed, 2002-03-20 at 19:06, Graham Klyne wrote:
> At 06:41 PM 3/20/02 -0500, Tim Berners-Lee wrote:
> >The URI spec tells us that the significance of the URI with the hash
> >on is a function of the language of  document you get when you
> >dereference the thing before the hash.  Therefore, for an RDF document,
> >RDF defines what the thing *with* the hash identifies (anything)
> 
> This feels to me like a confusion between the thing referenced and the 
> thing doing the referencing:
> 
>    RDF-doc  --references-->  something#fragment
> 
> As I understand the web principles, the meaning of #fragment here is not 
> dependent on the (MIME) content of 'RDF-doc', but of 'something'.

Graham's interpretation seems to be a nice brief summary of this piece
of RFC 2396:
------------------------------------
4.1. Fragment Identifier

   When a URI reference is used to perform a retrieval action on the
   identified resource, the optional fragment identifier, separated from
   the URI by a crosshatch ("#") character, consists of additional
   reference information to be interpreted by the user agent after the
   retrieval action has been successfully completed.  As such, it is not
   part of a URI, but is often used in conjunction with a URI.

      fragment      = *uric

   The semantics of a fragment identifier is a property of the data
   resulting from a retrieval action, regardless of the type of URI used
   in the reference.  Therefore, the format and interpretation of
   fragment identifiers is dependent on the media type [RFC2046] of the
   retrieval result.  The character restrictions described in Section 2
   for URI also apply to the fragment in a URI-reference.  Individual
   media types may define additional restrictions or structure within
   the fragment for specifying different types of "partial views" that
   can be identified within that media type.

   A fragment identifier is only meaningful when a URI reference is
   intended for retrieval and the result of that retrieval is a document
   for which the identified fragment is consistently defined.

------------------------------------

It also states that # is merely a separator, and fragment identifiers
are only meaningful in contexts which intend retrieval, complete with
MIME type identification.

-- 
Simon St.Laurent
Ring around the content, a pocket full of brackets
Errors, errors, all fall down!
http://simonstl.com
Received on Wednesday, 20 March 2002 20:59:59 GMT

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