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Re: HTML 4 Profile for RDFa

From: Shelley Powers <shelleyp@burningbird.net>
Date: Sat, 23 May 2009 15:24:58 -0500
Message-ID: <4A185B9A.8060002@burningbird.net>
To: Julian Reschke <julian.reschke@gmx.de>
CC: Shane McCarron <shane@aptest.com>, Philip Taylor <pjt47@cam.ac.uk>, Sam Ruby <rubys@intertwingly.net>, RDFa Community <public-rdfa@w3.org>, "public-rdf-in-xhtml-tf.w3.org" <public-rdf-in-xhtml-tf@w3.org>, HTML WG <public-html@w3.org>
Julian Reschke wrote:
> Shane McCarron wrote:
>> Julian Reschke wrote:
>>>
>>> It's clear that if RDFa is to be used with prefix declarations done 
>>> with xmlns, then mixing uppercase and lowercase declarations is not 
>>> going to work.
>>>
>>> I think restricting prefixes to be lower-case (insert proper Unicode 
>>> terminology here) would be acceptable; it's easy to live with, and 
>>> avoids introducing yet another prefix declaration mechanism.
>> I would not be opposed to adding text in the RDFa in HTML definition 
>> like "prefix names SHOULD be defined in lower-case to help ensure 
>> maximum portability among parsers, since it is common for DOM-based 
>> parsers to not preserve the case of attribute names."
>>
>> I don't see there being any need to change the definition of 
>> XML-based languages like RDFa for XHTML.  After all, in XML case is 
>> preserved.  Or is ot someone's goal that documents be able to be 
>> parsed as EITHER XML or HTML?  It's not my goal.  If I define a 
>> document using an HTML family 
>
> I know Sam wants that. But if there's a simple way to achieve this, 
> such as only using lower-case prefixes, that should be totally 
> sufficient...
>
>> ...
>
> BR, Julian
>
>
I agree with Shane. We don't have the same rules for parsing XHTML and 
HTML now. We shouldn't make an exception for RDFa in HTML, as compared 
to RDFa in XHTML.

As for xmlns as compared to XMLNS, this is already included in the HTML5 
spec. I'm assuming the spec will defer to the XML definition for xmlns, 
which means lowercase preservation.

Regarding lower or upper case prefixes, well this goes beyond any 
specific issue having to do with RDFa. I would say that eventually the 
HTML5 specification is going to have to provide clarification on this, 
but it will regardless of anything to do with RDFa. Correct?

I would also say that RDFa applications will have to be aware of whether 
the document is served as XHTML, as compared to HTML. Right now, RDFa is 
technically supported in XHTML, which means that there may be uppercase 
prefixes here and there. These should still be valid in the future. 
What's new is RDFa in HTML, in which case the RDFa extraction 
applications, such as those Philip used in his test suit will have to be 
modified to handle a new set of requirements. Appropriately so. And this 
isn't "breaking" the web either, because these are new requirements, 
based on RDFa being now supported in HTML.

Am I looking at the issue in too simplistic a manner?

Shelley
Received on Saturday, 23 May 2009 20:25:53 GMT

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