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Re: @rel syntax in RDFa (relevant to ISSUE-60 discussion), was: Using XMLNS in link/@rel

From: Sam Ruby <rubys@intertwingly.net>
Date: Sun, 01 Mar 2009 05:46:43 -0500
Message-ID: <49AA6793.6000503@intertwingly.net>
To: Mark Nottingham <mnot@mnot.net>
CC: Ben Adida <ben@adida.net>, Manu Sporny <msporny@digitalbazaar.com>, "www-tag@w3.org WG" <www-tag@w3.org>, HTMLWG WG <public-html@w3.org>, RDFa mailing list <public-rdf-in-xhtml-tf@w3.org>, public-xhtml2@w3.org
Mark Nottingham wrote:
> 
> On 01/03/2009, at 10:33 AM, Ben Adida wrote:
> 
>> Mark Nottingham wrote:
>>> Are people using RDFa in HTML using the profile mechanism, or xmlns, or
>>> both? Do they flag the use of RDFa in any way (like @version does for
>>> XHTML+RDFa)?
>>
>> We recommend using the doctype with @version. We've determined that,
>> while @profile is the right approach for interpreting new values of
>> @rel, it doesn't cover new attributes, so it's not the right way to flag
>> RDFa.
> 
> Sorry, I should have been more clear; I'm talking about in HTML4 (since 
> CC doesn't require or recommend XHTML for CC+).
> 
[snip]
> 
> But an HTML4 parser has absolutely no business knowing about xmlns, period.

I think we use these terms differently than users do.

$ curl --silent --head http://www.whitehouse.gov/ | grep -i content-type
Content-Type: text/html; charset=utf-8
$ curl --silent http://www.whitehouse.gov/ | head -3 | tail -1
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" 
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

 From a user perspective features are things like canvas or RDFa.  Add a 
little markup, include a bit of javascript and you have awesome graphics 
or delectable metadata.

 From a HTTP perspective, HTML is unversioned... there is no way to 
indicate via a MIME type whether something is HTML4 vs HTML5, just a way 
to indicate something is HTML vs XHTML; and that is done is a way that 
is beyond what most users can control and is at variance with what users 
understand XHTML to be and is entirely unsupported by the dominant 
browser.  And triggers unforgiving error recovery strategies.

 From a browser perspective, HTML is unversioned.  No browser that 
supports canvas will refuse to do so simply because that tag is included 
in a page which includes the HTML4 DOCTYPE.  Firefox (to pick an 
concrete example) has no plans to have a separate HTML5 parser. 
Javascript libraries which will extract RDFa data will do so even in 
quirks mode.  Even if the attributes happen to be named starting with 
the characters 'x', 'm', and 'l'.

Users who are attracted to RDFa today are likely to have been influenced 
either directly or indirectly by Zeldman and his brethren.  They include 
an XHTML DOCTYPE and try to be careful about quotes.  The few that 
actually read specs will see that XHTML 1.0 Transitional allows the use 
of the text/html MIME type.

I am biased.  I believe that we should cater to these users.  They 
outnumber us.

- Sam Ruby
Received on Sunday, 1 March 2009 10:46:53 GMT

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