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Comments on XHTML Metainformation module 22 July WD

From: Ralph R. Swick <swick@w3.org>
Date: Mon, 06 Sep 2004 20:45:12 -0400
Message-Id: <>
To: www-html-editor@w3.org
Cc: public-rdf-in-xhtml-tf@w3.org

Comments on http://www.w3.org/TR/2004/WD-xhtml2-20040722/

I read only sections 19 Metainformation Attributes Module and
20 Metainformation Module and followed some of the references
so if any of my questions are answered in other sections please
accept my apologies and consider this a suggestion to add more

Overall I am excited to see these two sections proposed for
XHTML.  These two modules have the potential to permit integration
of RDF graphs into XHTML documents in a way that should be a
relatively small learning curve for XHTML users.  I am disturbed,
however, by the lack of explicit connection to RDF semantics.  The
module is eminently suited to expressing RDF semantics, and to use
RDF to give precise interpretation of the semantics of the new
XHTML vocabulary, but sadly this opportunity has not been taken.
It ought to be straightforward to say that the URI that is the
value of a property attribute corresponds to the URI that names
an RDF property, that the URI that is the value of an about or
resource attribute corresponds to the RDF subject and that the
metadata value, whether specified by the content attribute or
by element content, is the RDF object of a statement.  This would
then make it possible to define a normative GRDDL [1] transform
from this metadata syntax to an RDF graph.  I hope this can be
rectified in a future Working Draft.

[1] http://www.w3.org/TR/grddl/

In Section 19.1, in the second example for the rel attribute, the
example shows the media attribute.  Does this attribute have any
intended metadata semantics?  While the other attributes have
a relatively obvious representation in an RDF graph (though that
representation should be made explicit), it is not clear what
representation the media attribute might be intended to have.

In Section 19.1 in the description of the restype attribute, the
words "The user agent must combine ..." are used.  I recommend
that this be changed to 'should combine', as there is no apparent
need to require user agents to understand the semantics of this
particular piece of the metainformation module.  If a user agent
fails to intersect the restype value with its own acceptable media
types, the server will still behave in an appropriate manner.

Section 19.3 refers to the property xhtml2:reference.  Is this
property further defined somewhere?  I note that this example
shows that the value of this property (e.g. the rdfs:Range)
can be either a string or a resource.

Section 20.1 uses the URI value
http://example.com/people/MarkBirbeck/654 to refer to a person.
For pedagogical reasons [2,3], it would be good to use URIs not
containing a '#' only to refer to documents and to use a URI
such as http://example.com/people/MarkBirbeck#654 to refer to
the non-document.  The same change should be made to the examples
in section 20.3.2.

[2] http://www.w3.org/DesignIssues/HTTP-URI.html
[3] http://www.w3.org/TR/webarch/#fragid

Section shows two examples of property names that do not
have namespace qualifiers.  To be consistent with other similar
uses, the reader should interpret these properties as being in
the xhtml2 namespace.  I doubt that is what was intended.
I recommend that a well-known namespace such as Dublin Core
be used in this example.  A similar problem occurs in section  In that section, however, the intent is to show
a not-recommended usage.  So I suggest that the example include
an XML comment saying that this example should not be followed.

Section 20.2.2 refers to the href attribute.  What correspondence
is there between the href attribute used in this case and the
resource attribute used elsewhere?

Sectio 20.2.3 refers to 'lists' of property names.  I suggest that
the term 'vocabularies' conveys your intent and would be understood
both by readers familiar with HTML and readers familiar with RDF.

Sections 20.3.2 and 20.4 were damaged in your Postscript and PDF versions.

The second example in section 20.4 uses a property QName whose
namespace has not been shown to be declared (con:).  The explanation
of this example would be more precise if it where to read as
"1. The quote has a source identified by ISBN.  (This ISBN number
is assigned to the book Crime and Punishment, though this metadata
example does not supply that particular information.)"

I am confused by section 20.5.2.  The text says that the value of
the title for the French manual is specified as being in the French
language, however the French example is not obviously different
from the other 3 examples.  I suspect that all four examples
are intended to specify the (XML) language of their respective
title values.

I suggest that the example at the end of section 20.6 is misleading.
It says that a string value has identical semantics to the value
of a resource attribute.  I suggest that it is unwise to specify that
any string value that has valid URI syntax should be interpreted
as identifying a resource.

-Ralph Swick
Received on Tuesday, 7 September 2004 00:46:47 UTC

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