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Re: Generic processing of Fragment IDs in RFC 3023bis

From: Graham Klyne <GK-lists@ninebynine.org>
Date: Mon, 11 Oct 2010 16:28:16 +0100
Message-ID: <4CB32D10.8000004@ninebynine.org>
To: Tim Berners-Lee <timbl@w3.org>
CC: Jonathan Rees <jar@creativecommons.org>, "www-tag@w3.org" <www-tag@w3.org>
Tim Berners-Lee wrote:
 > If rdf:ID is defined as having uniqueness constraints then it is surely 
broken for
 > RDF as the same thing can of course be referred to in lots of of places
 > in the file, with exactly the same syntax.

Well, yes.  I tend to ignore it in favour of rdf:about, for that reason.

I think the constraints are a diluted carry over from the earlier RDF spec.

According to the W3C validator (http://www.w3.org/RDF/Validator/), the following 
is broken in exactly the way you suggest:
[[
<?xml version="1.0"?>
<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
   xmlns:dc="http://purl.org/dc/elements/1.1/">
   <rdf:Description rdf:ID="a">
     <dc:title>A label for 'a'</dc:title>
   </rdf:Description>
   <rdf:Description rdf:ID="a">
     <dc:creator>A creator for 'a'</dc:creator>
   </rdf:Description>
</rdf:RDF>
]]

[[
Error: {W105} Redefinition of ID: a[Line = 7, Column = 31]
Error: {W105} Previous definition of 'a'.[Line = 4, Column = 31]
]]

#g
--

Tim Berners-Lee wrote:
> If rdf:ID is defined as having uniqueness constraints then it is surely broken for
> RDF as the same thing can of course be referred to in lots of of places 
> in the file, with exactly the same syntax. 
> 
> Tim
> 
>>
>>
>> Jonathan Rees wrote:
>>> [...] The RDF/XML DTD
>>> (http://www.w3.org/XML/9710rdf-dtd/rdf.dtd) gives the rdf:ID attribute
>>> type ID, and the XML specs (including xml:id and Xpointer) do their
>>> very best to ensure that attributes with type ID are as much as
>>> possible the same as xml:id. The RDF/XML spec also makes rdf:ID very
>>> similar to xml:id - same syntactic and uniqueness constraints. So it
>>> seemed highly likely to me that rdf:ID defines fragids the same way
>>> that xml:id does.
> 
> 
Received on Monday, 11 October 2010 15:30:06 GMT

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