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Comments on RDFa Syntax version 1.8 2007/04/06 16:36:34

From: Fabien Gandon <Fabien.Gandon@sophia.inria.fr>
Date: Thu, 12 Apr 2007 18:28:46 +0200
Message-ID: <461E5E3E.5060307@sophia.inria.fr>
To: public-rdf-in-xhtml-tf@w3.org


To catch up with the RDFa work I reviewed the draft "RDFa Syntax: A
collection of attributes for layering RDF on XML languages" [1] in its
version 1.8 2007/04/06 16:36:34.
I hope to get time to update the RDFa2RDFXML transformation [2] to
reflect latest changes.

Below are some comments,


[1] http://www.w3.org/2006/07/SWD/RDFa/syntax/
[2] http://www-sop.inria.fr/acacia/soft/sweetwiki.html

Comment #1 - xml:base and produced triples
Section 2.3 "Using xml:base" explains how to handle the about=""

And the produced triples in the examples show the right URL for the document
<http://internet-apps.blogspot.com/>   dc:creator

However in the other examples the code uses the "< >" notation which I
find confusing since they represent extracted triples and thus they
should refer to the document they were extracted from instead of using a
self-reference which is no longer correct if the triple is no longer in
its source document (see extracted triples in sections 2.2.1, 2.4, 3.4,
4.2.5, 4.3.3, 5.1.1, 5.3, 6.2). I think the URL of the document or its
base should always be explicit in the extracted triples especially since
this self-reference could be used to add metadata to extracted triples e.g.:

<photo1.jpg> dc:creator <http://www.blogger.com/profile/1109404> .
<http://www.blogger.com/profile/1109404> foaf:img <photo1.jpg> .
<photo1.jpg> dc:title "Portrait of Mark" .
<http://internet-apps.blogspot.com/> cc:license
<http://creativecommons.org/licenses/by/nc-nd/3.0/> .
< > dc:date "2007/04/12/"^^xsd:Date .

Comment #2 - namespace declaration
The example in section 3.3 "Relating document components" declares only
the dc namespace.
In my opinion in this example, either you declare no namespaces at all
or you declare all the namespaces you use: taxo, rdf, biblio.

Moreover I think section 2.4 "Using CURIEs" should mention how the CURIE
prefixes are resolved to namespaces.

Comment #3 - Section 4.4 Establishing the subject
You wrote " At a high level, the subject of a statement is determined by
the about attribute, either on the element or on the closest parent of
that element. Two exceptions to that rule exist. First, if a closer
parent element includes a rel or rev attribute with no href, then the
subject is the CURIE/URI that corresponds to that parent element (as
described previously in object resolution.) Second, if the [RDFa
element] under consideration is a META or LINK without an about, then
the subject is the immediate parent element's CURIE/URI equivalent."

I found the use of "closet parent", "closer parent" and "immediate
parent" confusing I think the terminology of XPath axes "ancestor",
"parent", "child", "descendant", etc. ( http://www.w3.org/TR/xpath#axes
) is better and should be used in all the document as you did for
instance in section 4.4.2 "Inheriting the about attribute"

Comment #4 - Section 4.4.3 rel and rev attributes in ancestor elements

You wrote "During the ancestor element traversal, one may encounter an
element with a rel or rev attribute without a corresponding href
attribute. As described in object resolution, this situation defines a
new subject for all its children elements, in particular the currently
considered [RDFa element]. Specifically, the CURIE/URI associated with
this ancestor element becomes the subject."

So if I understand this well a node may become a subject when there is a
rel on it but couldn't we have the same case when it contains a link
element  ? I.e. could we have a case that looks like the following one
(I may have mixed up the syntax)

The following example:
<div about="album.html">
  <span rel="eg:finished">
     First page
   <span>This photo was taken by
     <span property="dc:creator">thomas</span>

Would produce:
<_:span0> eg:finished <_:span0>
<_:span0> dc:creator "thomas"^^rdf:XMLLiteral

While the following example the subject of dc:creator changes:
<div about="album.html">
     <link rel="eg:finished" />
     First page
   <span>This photo was taken by
     <span property="dc:creator">thomas</span>

Would produce:
<_:span0> eg:finished < >
<album.html> dc:creator "thomas"^^rdf:XMLLiteral

Comment #5 - Section 5.3 Reification

You wrote "this document is licensed under a Creative Commons license,
and that "Ben Adida" is the creator of that licensing statement,"

I may be picky here but I think there is no formal link between the
licensing triple and the statement thus this is really saying that this
document is licensed under a Creative Commons license, and "Ben Adida"
is the creator of a statement saying that this document is licensed
under a Creative Commons license.

Ok, ok, this is a useless comment ;-)

Fabien - http://www.inria.fr/acacia/fabien/
Received on Thursday, 12 April 2007 16:29:21 GMT

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