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Re: [Proposal] ISSUE-42: How does RDFa deal with @src

From: Dan Brickley <danbri@danbri.org>
Date: Fri, 22 Jun 2007 10:04:28 +0200
Message-ID: <467B828C.5050703@danbri.org>
To: Ivan Herman <ivan@w3.org>
CC: mark.birbeck@x-port.net, RDFa <public-rdf-in-xhtml-tf@w3.org>

Ivan Herman wrote:
> Just for the records...
> 
> Ivan Herman wrote:
>> Mark,
>>
>>
> [snip]
>> Also, are we sure that
>>
>> <s> rdfs:label "alt".
>>
>> is the best representation for this? I am afraid of finding ourselves in
>> some endless discussion with, say, WAI people on the meaning of the
>> 'alt' attribute; one could also say that
>>
>> <s> rdfs:seeAlso "alt".

I wouldn't encourage this use.

> B.t.w., I realized yesterday evening (under the shower, the best place
> for these things:-) that this is wrong. The range of rdfs:seeAlso is
> defined to be rdf:Resource by the RDF Semantics, ie, it should not be
> used with a Literal as an object.

I guess you don't have a waterproof laptop? :)

Couple of errors there. In http://www.w3.org/2000/01/rdf-schema#

<rdf:Property rdf:about="http://www.w3.org/2000/01/rdf-schema#seeAlso">
   <rdfs:isDefinedBy rdf:resource="http://www.w3.org/2000/01/rdf-schema#"/>
   <rdfs:label>seeAlso</rdfs:label>
   <rdfs:comment>Further information about the subject 
resource.</rdfs:comment>
   <rdfs:range 
rdf:resource="http://www.w3.org/2000/01/rdf-schema#Resource"/>
   <rdfs:domain 
rdf:resource="http://www.w3.org/2000/01/rdf-schema#Resource"/>
</rdf:Property>

and

<rdfs:Class rdf:about="http://www.w3.org/2000/01/rdf-schema#Literal">
   <rdfs:isDefinedBy rdf:resource="http://www.w3.org/2000/01/rdf-schema#"/>
   <rdfs:label>Literal</rdfs:label>

   <rdfs:comment>The class of literal values, eg. textual strings and 
integers.</rdfs:comment>
   <rdfs:subClassOf 
rdf:resource="http://www.w3.org/2000/01/rdf-schema#Resource"/>
</rdfs:Class>


ie. it's rdfs:Resource not rdf:Resource, and that class has a subclass 
rdfs:Literal, which means that there can be some resources that are 
literals (and that all literals are resources). This is counter to 
various uses of the word "resource" from 1999-era RDF. Since RDFCore, 
"resource" means, more or less, "thing". There is no named class for 
non-literal resources (although this could be expressed in OWL).

That said, the general assumption with seeAlso is that it relates 
(broadly) information resources to each other. We just never had such a 
class defined. Using it to point to a string seems wrong. Just because 
the schema doesn't formally outlaw it, doesn't make it a good usage.

http://esw.w3.org/topic/UsingSeeAlso is a good place for keeping notes 
on community expectations around seeAlso usage.

As an aside from RDFa, ... one usage I've not seen yet, but which might 
be interesting, is to have the cited graph packed into a data: URI.

> 				But there is also rdfs:comment, for
> example, that could be used instead of rdfs:label, so the original
> argument holds...
> 
> Ivan
> 
Received on Friday, 22 June 2007 08:04:42 UTC

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