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Re: Why is xml:lang not allowed on typed literals?

From: <jan.grant@bristol.ac.uk>
Date: Thu, 15 Oct 2009 12:12:16 +0100 (BST)
To: Bernard Vatant <bernard.vatant@mondeca.com>
cc: www-rdf-comments@w3.org
Message-ID: <alpine.BSF.2.00.0910151209061.23234@tribble.ilrt.bris.ac.uk>
On Thu, 15 Oct 2009, Bernard Vatant wrote:

> Hi all
> 
> This list does not seem very active, but hopefully someone is still
> monitoring it and will be able to answer
> 
> In
> http://www.w3.org/TR/2004/REC-rdf-concepts-20040210/#section-Graph-Literal I
> read
> 
> Plain literals have a lexical
> form<http://www.w3.org/TR/2004/REC-rdf-concepts-20040210/#dfn-lexical-form>and
> optionally a language
> tag as defined by
> [RFC-3066<http://www.w3.org/TR/2004/REC-rdf-concepts-20040210/#ref-rfc-3066>],
> normalized to lowercase.
> 
> Typed literals have a lexical
> form<http://www.w3.org/TR/2004/REC-rdf-concepts-20040210/#dfn-lexical-form>and
> a datatype
> URI being an RDF URI
> reference<http://www.w3.org/TR/2004/REC-rdf-concepts-20040210/#dfn-URI-reference>
> .
> 
> Between the lines I read that the language tag xml:lang is not allowed on
> typed literals. Actually I just tried to do this. The rationale is to define
> a datatype "One Sentence" which must contain a single sentence, starting
> with a upper-case, ending with a dot etc ... and using this datatype for a
> "tagLine" property - which of course has also a language.
> 
> So I tried the syntax below and proposed it to various tools
> 
> - W3C validator validates it, seems to ignore the xml:lang tag
> 
> - Prot?g? does the same, imports the file and ignores the xml:lang tag when
> saving
> 
> - SWOOP does the other way round, ignores the rdf:datatype but keeps the
> language tag.
> 
> My question is, just out of curiosity, what is the rationale behind not
> allowing xml:lang on typed literals?
> 
> Thanks for any clue

I believe the rationale was along the lines that if the value of a typed 
literal was represented by an XML construction, the xml:lang belonged _in_ 
the representation, not _on_ it. That is, that if a literal's values are 
represented in infoset terms, the xlm:lang belongs in the representation.


-- 
jan grant, ISYS, University of Bristol. http://www.bris.ac.uk/
Tel +44 (0)117 3317661   http://ioctl.org/jan/
Usenet: The separation of content AND presentation - simultaneously.
Received on Thursday, 15 October 2009 11:13:03 GMT

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