W3C home > Mailing lists > Public > public-rdf-in-xhtml-tf@w3.org > October 2004

Literals and XHTML 2 meta stuff

From: Jeremy Carroll <jjc@hplb.hpl.hp.com>
Date: Thu, 21 Oct 2004 16:46:39 +0100
Message-ID: <4177D9DF.6000502@hplb.hpl.hp.com>
To: "'public-rdf-in-xhtml task force''" <public-rdf-in-xhtml-tf@w3.org>



I have an outstanding action to clarify my concerns about literals.

Unfortunately I still haven't allocated long enough to do the job 
properly, so I am afraid I'll sketch the worries without adequately 
linking to the doc ... forgive me if I make silly mistakes ...

Starting point:

Literal text in the html doc gets translated into RDF XML Literals, 
except where an explicit datatype is mentioned.
(Motivation: text in html can have markup included)


Observations:

1)
There does not seem to be any method for adding a plain literal to the 
metadata.

e.g. if I have a triple of the form

<http://example.org/doc> dc:creator "Jeremy Carroll" .

where "Jeremy Carroll" is a plain literal then I cannot include this in 
an XHTML 2.0 document.

2)
Language is a problem:

Suppose I have the following triple in an XHTML document

<http://example.org/doc> dc:creator "A Guide to Markup"^^rdf:XMLLiteral .

and suppose that somewhere there is an in-scope xml:lang="en" attribute 
within the XHTML document.
Since rdf:XMLLiteral is a datatype, it does *not* have the capability to 
  be language modified. The RDF Core WG, when making this decision, 
noted that such language markup could be added into the XHTML e.g. 
instead of the above triple, we have:

<http://example.org/doc> dc:creator "<span xmlns=\".../xhtml2...\" 
xml:lang=\"en\">A Guide to Markup</span>"^^rdf:XMLLiteral .

I suggest that this insertion of <span> with xml:lang is always done.

3) I think it will surprise some RDFers to find all their metadata 
coming out as rdf:XMLLiterals or even (if 1 is addressed) any metadata 
that is not declared as not rdf:XMLLiteral.
I don't see anyway round this, and personally hope this will encourage 
the RDF community to take embedded XHTML within RDF more seriously. e.g. 
providing tool support for searching within XHTML as XHTML within RDF 
content.




I think that's about it. I hope there is enough detail there to be 
intelligible.

Jeremy
Received on Thursday, 21 October 2004 15:47:27 GMT

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