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Re: Next steps for the ARIA syntax discussion

From: Jon Gunderson <jongund@illinois.edu>
Date: Tue, 3 Jun 2008 09:50:58 -0500 (CDT)
To: Charles McCathieNevile <chaals@opera.com>, Cameron McCormack <cam@mcc.id.au>
Cc: elharo@metalab.unc.edu, Al Gilman <Alfred.S.Gilman@ieee.org>, "Henry S.Thompson" <ht@inf.ed.ac.uk>, "www-tag@w3.org List" <www-tag@w3.org>, "public-html@w3.org WG" <public-html@w3.org>, "public-xhtml2@w3.org WG" <public-xhtml2@w3.org>, "wai-xtech@w3.org WAI-XTECH" <wai-xtech@w3.org>
Message-Id: <20080603095058.BGJ59033@expms1.cites.uiuc.edu>

Firefox 3.0 for Windows gives the following error with the attached example:

XML Parsing Error: must not undeclare prefix
Location: file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/testBlankNS.xhtml
Line Number 2, Column 1:<html xmlns="http://www.w3.org/1999/xhtml" xmlns:foo="">

---- Original message ----
>Date: Sun, 01 Jun 2008 04:21:41 +0200
>From: "Charles McCathieNevile" <chaals@opera.com>  
>Subject: Re: Next steps for the ARIA syntax discussion  
>To: "Charles McCathieNevile" <chaals@opera.com>, "Cameron McCormack" <cam@mcc.id.au>
>Cc: elharo@metalab.unc.edu, "Al Gilman" <Alfred.S.Gilman@ieee.org>, "Henry S.Thompson" <ht@inf.ed.ac.uk>, "www-tag@w3.org List" <www-tag@w3.org>, "public-html@w3.org WG" <public-html@w3.org>, "public-xhtml2@w3.org WG" <public-xhtml2@w3.org>, "wai-xtech@w3.org WAI-XTECH" <wai-xtech@w3.org>
>On Sun, 01 Jun 2008 04:11:41 +0200, Charles McCathieNevile  
><chaals@opera.com> wrote:
>> On Sun, 01 Jun 2008 03:28:19 +0200, Cameron McCormack <cam@mcc.id.au>  
>> wrote:
>>> Charles McCathieNevile:
>>>> What it really means is that the appropriate namespace for these
>>>> attributes is the empty string - xmlns:aria="" if you are going to use
>>>> aria:aria-[something] in a namespace aware environment, but
>>>> aria-[something] will work perfectly correctly in both a
>>>> namespace-reliant environment, and in a namespace-unaware environment,
>>>> because of a careful and thoughtful design decision in the namespaces
>>>> specification that allows for the easiest possible transition between  
>>>> the
>>>> two kinds of environment.
>>> A small note: you cannot use xmlns:aria="" to declare that the aria
>>> prefix corresponds to no namespace.  The only way to have an attribute
>>> be in no namespace in markup is for it to have no prefix.
>>>   http://www.w3.org/TR/REC-xml-names/#dt-prefix
>> Argh. This spec is hard to read, although short. I read the "In such  
>> declarations, the namespace name may not be empty" in line with RFC  
>> 2119, whereas I think you are reading it in a looser way where normal  
>> people would interpret it as that RFC-2119 equivalent 'In such  
>> declarations, the namespace name must not be empty'. I haven't tested  
>> this in practice either, although I note that the spec doesn't require  
>> processors actually check what the namespace values are in any event.
>> If I don't run out of time tonight I might try to write a test case for  
>> this.
>I knocked together an attempt at one that may have other fatal quality  
>problems, but it showed that both Opera 9.5 and Safari (whatever I have on  
>my machine) do reject namespace prefixes that are null. Which is enough  
>for me to accept Cam's reminder as explaining the truth. I don't think  
>that changes my argument, but I am glad to have learned that I had missed  
>I attached the test in case anyone thinks it is worth playing with. It's  
>fairly likely that some stupid error means it wouldn't work anyway (I did  
>exactly zero QA on it, just wrote some stuff without thinking and opened  
>it in a couple of browsers), but feel free to play with this in any way  
>you see fit (or delete, which is probably reasonable behaviour).
>Charles McCathieNevile  Opera Software, Standards Group
>     je parle franšais -- hablo espa˝ol -- jeg lŠrer norsk
>http://my.opera.com/chaals   Try Opera 9.5: http://snapshot.opera.com
>testBlankNS.xhtml (1k bytes)
Jon Gunderson, Ph.D.
Coordinator Information Technology Accessibility
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Received on Tuesday, 3 June 2008 18:07:59 UTC

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