<text:meta> and xhtml:resource/xhtml:typeof attributes

[S�ren Roug <soren.roug@eea.europa.eu>]

Dear office-comment list,

RDF has two principal datatypes. Resources and literals. An RDF literal 
matches the simple type concept in C, whereas a resource matches a 
*pointer* to an object. There seems to be no way to create resources 
using the <text:meta> element.

In RDF you can create the following triple (I hope it doesn't get mangle 
too much by the email system):

<rdf:Description rdf:about="http://dbpedia.org/resource/Albert_Einstein";>
<dbp:birthPlace rdf:resource="http://dbpedia.org/resource/Germany/";>
</rdf:Description>

I essentially means that Albert Einstein identified by the URL 
http://dbpedia.org/resource/Albert_Einstein was born in Germany, 
identified by the resource http://dbpedia.org/resource/Germany. The 
point is that by declaring it as a resource, an inference engine will 
expect to find out more about Germany at the indicated URL, by 
retrieving an RDF document from the location.

This is different from:
<rdf:Description rdf:about="http://dbpedia.org/resource/Albert_Einstein";>
<dbp:birthPlace>http://dbpedia.org/resource/Germany/</dbp:birthPlace>
</rdf:Description>

..where "http://dbpedia.org/resource/Germany/"; is just a text string 
that happens to look like a URL.

If you try to write that in ODF 1.2 using <text:meta>, you'd need:

<text:meta xhtml:about="[dbr:Albert_Einstein]"
    xhtml:property="[dbp:birthPlace]"
    xhtml:resource="[dbr:Germany]">Albert Einstein was born in 
Germany</text:meta>

But xhtml:resource is not available unlike in RDFa (See 
http://www.w3.org/TR/rdfa-syntax/)

The second issue is that the xhtml:typeof attribute is missing from the 
ODF spec.

The xhtml:typeof is a shorthand for declaring the type of the object you 
are creating with <text:meta>. Using the same example, but this time we 
want to also declare that Albert is a person:

<rdf:Description rdf:about="http://dbpedia.org/resource/Albert_Einstein";>
<rdf:type rdf:resource="http://xmlns.com/foaf/0.1/Person"/>
<dbp:birthPlace rdf:resource="http://dbpedia.org/resource/Germany/";>
</rdf:Description>

Declaring the object type is so useful in the Semantic Web that RDF has 
a shorthand for it:

<foaf:Person rdf:about="http://dbpedia.org/resource/Albert_Einstein";>
<dbp:birthPlace rdf:resource="http://dbpedia.org/resource/Germany/";>
</foaf:Person>

This was also recognised by the RDFa committee, and they created the 
xhtml:typeof attribute for it.

In ODF 1.2 using <text:meta>, you'd need:

<text:meta xhtml:about="[dbr:Albert_Einstein]"
    xhtml:typeof="[foaf:Person]"
    xhtml:property="[dbp:birthPlace]"
    xhtml:resource="[dbr:Germany]">Albert Einstein was born in 
Germany</text:meta>


Best regards,

S�ren Roug