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Re: Treatment of RDFa in TAG Finding on Self-describing Web

From: <noah_mendelsohn@us.ibm.com>
Date: Fri, 12 Sep 2008 18:18:46 -0400
To: Ben Adida <ben@adida.net>
Cc: Mark Baker <distobj@acm.org>, Steven Pemberton <steven.pemberton@cwi.nl>, www-tag@w3.org
Message-ID: <OF08D6A3D0.C2A54890-ON852574C2.00793300-852574C2.007A5D9B@lotus.com>
Ben Adida writes:

> we *have* (or at least have resolved to and will very soon) update 
> the XHTML namespace document to reflect how RDFa can and should be 
> interpreted.

> I believe that is the "missing link" in the reasoning, but please let me
> know if I'm incorrect.

Can you show me the chain of normative speficiations, starting with the 
registration for the media type, that passes through (will pass through) 
that updated XHTML namespace document?  The current namespace document for 
http://www.w3.org/1999/xhtml says The namespace name 
http://www.w3.org/1999/xhtml is intended for use in various specifications 
such as:  * XHTML™ 1.0: The Extensible HyperText Markup Language,  * XHTML 
Modularization,  * XHTML 1.1,  * XHTML Basic.  Fair enough, but saying 
that a namespace is intended for use in a specification seems like a 
pretty oblique way of saying:  when you see a document that has 
<xhtml:html> as its root, the syntactic and semantic rules for that 
document are....

Frankly, I find RFC 3236 a bit oblique in the way it tries to say that 
it's intended to apply to XHTML at all.  For example, in the Introduction, 
it describes the history of the invention of XHTML, and then in the 3rd 
paragraph it says that the purpose of the RFC is "only" to register a new 
MIME media type.  It in fact later goes to some trouble to point out that 
it correctly uses application/xxxxx+xml syntax, and that documents of this 
media type are to conform to the syntax of XML 1.0.  As far as I can tell, 
it never says in so many words that the documents are to conform to the 
syntax of or be interpreted as XHTML.

So, if I've read it right, we're building on a somewhat shaky or at best 
informal base.

Regarding the XHTML namespace, the media type regstration says only: 

"All XHTML files should also include a declaration of the XHTML namespace. 
 This should appear shortly after the string "<html", and should read 
'xmlns="http://www.w3.org/1999/xhtml"'.

OK, fine as far as it goes, but I don't see that making any normative 
references to the namespace document that you're proposing to update.  So, 
I'm still looking for the chain of normative references that says:  the 
media type is application/xhtml+xml so RFC 3236 applies, which says that 
specification XXX applies which says that specification YYY applies ... so 
the RDFa is to be interpreted as per the new RDFa Syntax and Processing 
Recommendation.  If that chain goes through the namespaces document fine, 
and I apologize if I'm being dense for not seeing the path through this. 
Thank you again for your patience.

Noah

--------------------------------------
Noah Mendelsohn 
IBM Corporation
One Rogers Street
Cambridge, MA 02142
1-617-693-4036
--------------------------------------








Ben Adida <ben@adida.net>
09/11/2008 02:36 AM
 
        To:     Mark Baker <distobj@acm.org>
        cc:     noah_mendelsohn@us.ibm.com, Steven Pemberton 
<steven.pemberton@cwi.nl>, www-tag@w3.org
        Subject:        Re: Treatment of RDFa in TAG Finding on 
Self-describing Web



I think it's worth noting that this is RDFa in XHTML1.1, and that we
*have* (or at least have resolved to and will very soon) update the
XHTML namespace document to reflect how RDFa can and should be 
interpreted.

I believe that is the "missing link" in the reasoning, but please let me
know if I'm incorrect. I wanted to make sure this point was made before
Noah has to publish the TAG finding.

-Ben

Mark Baker wrote:
> Noah,
> 
> On Tue, Sep 9, 2008 at 5:52 PM,  <noah_mendelsohn@us.ibm.com> wrote:
>> * You then quote the RDFa Syntax and Processing draft: "There SHOULD be 
a
>> @version attribute on the html element with the value 'XHTML+RDFa 
1.0;".
>> Let's for the moment ignore that it's a SHOULD and consider the case 
where
>> @version is indeed set this way.  Is there something in RFC 3236 or 
XHTML
>> 1.0 to the effect that "a value in the @version attribute of the HTML
>> element is a key that can be used to identify additional 
specification(s)
>> that provide normative interpretations for markup beyond that which is
>> standardized for XHTML itself?"  As best I can tell, XHTML delegates
>> discussion of the <HTML> element to HTML 4.01, and that in turn says 
that
>> the version attribute is deprecated! [1]  Is there something normative 
in
>> either XHTML or M12N that says "go looking for a specification that 
seems
>> to have been written by the authority responsible for the namespace 
used
>> in the new markup?".
>>
>> So, I'm still missing some crucial connections.=
> 
> I think there is one connection missing; RDFa extends the meaning of
> rel (and rev) attribute values in a manner which HTML doesn't licence.
> 
> Often, IME, doing that sort of thing is a really bad idea, but not
> always.  In this case, rel attribute values are a fairly simple
> element of HTML, as they're just a list of opaque strings from a small
> dictionary, and AFAIK, there's no processors which try to treat them
> as anything more than that.  So RDFa's introduction of special meaning
> to a colon - a character unused in that dictionary - is effectively
> harmless.
> 
> That's not the end of the story of course, because while RDFa isn't
> self-descriptive, it should be made so.  What that requires is an
> update to HTML to anoint the special meaning of ":" in link types;
> 
>  http://www.w3.org/html/wg/html5/#linkTypes

> 
> So for your draft, you might consider expanding 4.1 to explain in more
> detail what it means to extend an existing media type
> self-descriptively in both the short and long term.
> 
> Mark.



Received on Friday, 12 September 2008 22:18:12 GMT

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