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Why is xml:lang not allowed on typed literals?

From: Bernard Vatant <bernard.vatant@mondeca.com>
Date: Thu, 15 Oct 2009 13:03:46 +0200
Message-ID: <9d93ef960910150403p69edc05bq1d5b24cc2f794fb3@mail.gmail.com>
To: www-rdf-comments@w3.org
Hi all

This list does not seem very active, but hopefully someone is still
monitoring it and will be able to answer

http://www.w3.org/TR/2004/REC-rdf-concepts-20040210/#section-Graph-Literal I

Plain literals have a lexical
optionally a language
tag as defined by
normalized to lowercase.

Typed literals have a lexical
a datatype
URI being an RDF URI

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

- Protégé does the same, imports the file and ignores the xml:lang tag when

- 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


<?xml version="1.0" encoding="UTF-8"?>

            <rdf:Description rdf:about="
                <rdfs:label xml:lang="en">Example Best Super
                <voc:tagLine xml:lang="fr" rdf:datatype="
http://example.org/datatype#OneSentence">Notre meilleur widget est le plus
beau et le moins cher du monde.</voc:tagLine>

Bernard Vatant
Senior Consultant
Vocabulary & Data Engineering
Tel:       +33 (0) 971 488 459
Mail:     bernard.vatant@mondeca.com
3, cité Nollez 75018 Paris France
Web:    http://www.mondeca.com
Blog:    http://mondeca.wordpress.com
Received on Thursday, 15 October 2009 11:04:21 UTC

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