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

>>>> 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.

Best, Jos

> 
> 
>>> Since the only normative exchange syntax for RIF and for RDF is XML then
>>> it is not actually possible to exchange characters sequences other than
>>> those expressible in the XML version one is dealing with. So we just
>>> have to be clear which version XML RIF is based on.
>>
>> It is always possible to define an embedding, but of course it would be
>> ideal if strings can be exchanged as such.
>>
>>> The most general solution is perhaps to say that the we regard the value
>>> space of xsd:string being that defined in XML 1.1. Exchange using XML
>>> 1.0 is entirely legal and permitted but the lexical space is then
>>> restricted slightly.
>>
>> I guess this is reasonable, because XML schema 1.1 has last call working
>> draft status.
> 
> Quite so, we're not that close ourselves :-)
> 
> Dave

-- 
Jos de Bruijn            debruijn@inf.unibz.it
                      http://www.debruijn.net/
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