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Re: Coming to consensus on the default datatype

From: Ivan Herman <ivan@w3.org>
Date: Wed, 21 Mar 2007 10:46:12 +0100
Message-ID: <4600FEE4.4080707@w3.org>
To: Ben Adida <ben@adida.net>
Cc: RDFa <public-rdf-in-xhtml-tf@w3.org>

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Ben,

thanks a lot for this summary. I could follow everything you said, and
usually agree, until the very end...:-( Where I was lost for a moment.
You list a bunch of use cases:

[snip]
> 
> So here's a proposal for discussion, which is only a slight tweak on the
> approach already mentioned by Mark and Steven, which is meant to make
> for easy defaults and reasonably easy override in both directions with DRY.
> 
> 1) Ian's use case:
> 
> <http://example.com/doc> dc:title "RDF or Bust" .
> 
> ========
> <h1 property="dc:title">RDF or Bust</h1>
> ========
> 
> 2) Mark's use case:
> 
> <http://example.com/doc> dc:title "E=mc<sup>2</sup>"^^rdf:XMLLiteral .
> 
> ========
> <h1 property="dc:title">E=mc<sup>2</sup></h1>
> ========
> 
> 3) Overriding the type when the markup is for presentation only:
> 
> <http://example.com/doc> dc:title "This guy is truly intelligent" .
> 
> ========
> <h1 property="dc:title" datatype="plain">
>    This guy is <em>truly</em> intelligent
> </h1>
> ========
> 
> 4) Overriding the type to stay consistent with other XMLLiteral data stores:
> 
> <http://example.com/doc> dc:title "E equals mc squared"^^rdf:XMLLiteral .
> 
> ========
> <h1 property="dc:title" datatype="rdf:XMLLiteral">
>    E equals mc squared
> </h1>
> ========
> 
> 
> I think we're pretty close to consensus on something like what Mark and
> Steven proposed, possibly with the above twist. 

But I am not sure from the text what the proposal is!:-( But let me try
to articulate it, maybe I get it right:

- - By default:
	- if the content contains xml elements of any kind, the literal is of
XMLLiteral
	- if the content does not contain any elements of any kind, the literal
is plain
- - You introduce (beyond the datatypes inherited from RDF/XML Schema, eg,
XMLLiteral) an extra value for the datatype that is 'plain', with the
obvious meaning.

I can very well live with that. The only mini-mini question is whether
we would have to have a separate namespace for this value, ie, it should
be 'rdfs:plain' instead of 'plain'.

Maybe we could also add the extra twist, ie, that if one uses
rdf:XMLLiteral, that would switch off, so to say, any RDFa processing in
the literal, too. Ie, that could solve Ian's puzzle; his

<div about="">
    <h2 property="dc:title">
      E = mc<sup property="rdf:value">2</sup>: The Most Urgent Problem
of Our Time
    </h2>
</div>

would have to use:

<div about="">
    <h2 property="dc:title" datatype="rdf:XMLLiteral">
      E = mc<sup property="rdf:value">2</sup>: The Most Urgent Problem
of Our Time
    </h2>
</div>

to generate the triple he needs...

Thanks

Ivan

- --

Ivan Herman, W3C Semantic Web Activity Lead
URL: http://www.w3.org/People/Ivan/
PGP Key: http://www.cwi.nl/%7Eivan/AboutMe/pgpkey.html
FOAF: http://www.ivan-herman.net/foaf.rdf
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Received on Wednesday, 21 March 2007 09:46:36 GMT

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