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Re: [RIF-RDF] (potential) issues regarding correspondence of identifiers

From: Jos de Bruijn <debruijn@inf.unibz.it>
Date: Mon, 03 Sep 2007 14:39:58 +0200
Message-ID: <46DC009E.3070301@inf.unibz.it>
To: Dave Reynolds <der@hplb.hpl.hp.com>
CC: RIF <public-rif-wg@w3.org>
>>>>>> There are some further differences between the specification
>>>>>> of the string datatype in XML schema 1.0 and XML schema 1.1; in the
>>>>>> former case, the datatype is based on the Char production in XML
>>>>>> 1.0; in
>>>>>> the latter case, the datatype is based on the Char production in XML
>>>>>> 1.1.
>>>>>> An important question is what to do with plain literals which contain
>>>>>> characters which are not in the lexical space of xsd:string.
>>>>> So there is a real difference there. XML 1.0 does not allow characters
>>>>> like BEL (those below #x20 other than #x9 #xA and #xD) XML 1.1 does
>>>>> allow those characters.
>>>> Are these characters (i.e. those below #x20 other than #x9 #xA and #xD)
>>>> actually Unicode characters?
>>> Yes, though they are control characters rather than displayable
>>> characters.
>>>
>>> Note that even though the XML1.1 spec allows them in the Char production
>>> it "discourages" them:
>>>
>>> [[[
>>> Document authors are encouraged to avoid "compatibility characters", as
>>> defined in Unicode [Unicode]. The characters defined in the following
>>> ranges are also discouraged. They are either control characters or
>>> permanently undefined Unicode characters:
>>>
>>> [#x1-#x8], [#xB-#xC], [#xE-#x1F], ...
>>> ]]]
>>
>> So, every RDF plain literal without a language tag is an xsd:string in
>> XML Schema 1.1, but there are plain literals without language tags which
>> are not xsd:strings in XML Schema 1.0.
>>
>> So, if we go for XML Schema 1.0, then we have to tackle this issue in
>> RDF compatibility.
> 
> Of course the only normatively defined format for RDF exchange (at
> present) is RDF/XML and people using XML 1.0 can't express the control
> characters anyway.

So, not every RDF graph can be exchanged with RDF/XML.  I guess this is
a bug in the specification?

Best, Jos

> 
> Dave

-- 
Jos de Bruijn            debruijn@inf.unibz.it
                      http://www.debruijn.net/
----------------------------------------------
As far as the laws of mathematics refer to
reality, they are not certain; and as far as
they are certain, they do not refer to
reality.
  -- Albert Einstein


Received on Monday, 3 September 2007 12:40:17 GMT

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