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re: updated: RDF/XML Media Type registration draft

From: pat hayes <phayes@ihmc.us>
Date: Tue, 26 Aug 2003 18:29:36 -0700
Message-Id: <p06001a17bb71b739f082@[]>
To: Larry Masinter <LMM@acm.org>
Cc: www-rdf-comments@w3.org

>"However, in RDF, the thing identified by a URI with
>fragment identifier does not bear any particular
>relationship to the thing identified by the URI alone.
>This differs from some readings of the URI
>specification[6], so attention is recommended when
>creating new RDF terms which use fragment identifiers."
>I confess to have never liked this attempt to use fragment
>identifiers in RDF to 'descend into meaning' rather than
>to identify a structural fragment;

There is a basic problem here, one that has been surfacing in the 
discussions on the TAG group. URIs are supposed to denote things, and 
also to indicate representations. These are different tasks. If URIs 
with fragIDs are required to denote structural fragments of RDF/XML 
documents, then RDF is made impossible; there is then no way to use a 
URI to denote anything other than a part of a document.

>  I think it's inconsistent,
>and leaves you no way to talk about structural fragments.

But why would anyone want to talk about structural fragments of 
RDF/XML documents in RDF? The idea is marginally crazy; but if 
someone really wanted to do this, the appropriate technique to use 
would surely be reification.

>The notion that the resource identified by
>"http://some.host/some.path#" and "http://some.host/some.path"
>are completely unrelated seems pathological.

They are related, but not by any kind of structural relationship: 
they are related by denotation. The URI without the fragID represents 
an RDF/XML document, which is a representation which contains 
assertions which *use* the URIref with the fragID to *refer to* 
entities. So they are the entities referred to in the document; and 
the use of the URI+fragID outside the document ensures that other 
documents can refer to the same entities. What other convention could 
*possibly* be used to ensure this?

>So not sure 'attention is recommended' captures
>the necessary caution.
>I think part of the problem is that the draft only
>addresses URI references with fragment identifiers
>when those URI references are used _as RDF terms_.
>But what about other uses? If I have a web page with
><a href="http://some.host/some.path#concept">link
>to a concept</a>
>what might a legitimate response be to clicking
>on that as a link? I can't tell from this document
>or the documents it references.

Why would RDF need to specify this? RDF is not intended for 
responding to clickings on URIrefs. HTML does not specify what 
URIrefs denote, either. They live in different worlds.

Pat Hayes

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Received on Tuesday, 26 August 2003 21:29:36 UTC

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