Empty xml:lang attributes validation

Hi,

On Mon, Nov 30, 2009 at 10:42 AM, Steven Pemberton
<Steven.Pemberton@cwi.nl>wrote:

> There's something slightly odd with classifying people's names as being in
>>> the same language as the document:
>>>
>>>       <http://drupalrdf.openspring.net/user/20> a sioc:User ;
>>>            foaf:name "lucerukimam"@en .
>>>
>>
>> good point. This is inherited from the xml:lang="en" attribute of the html
>> tag of the document. Is there anyway in RDFa to reset this language tag in
>> the markup? is adding xml:lang="" to the tag containing the foaf:name the
>> right way to do it?
>>
>
> Yes.


We fixed the Drupal RDFa markup to reset the language of the username
following the above, see example [1]. The markup validates with the W3C
validator [2], however we got a bug report [3] about
http://www.totalvalidator.com/ not validating the markup due to xml:lang="".
I have never heard of Total Validator, and I consider the W3C validator
authoritative, but the Total Validator mentions at [4] that it "uses the
official W3C and ISO DTDs for HTML Validation and the tests are automated
from these - in other words we haven't personally made up the validation
rules or translated them. So if TV finds a problem on your page (or fails to
find one) then it's highly likely that it's in the W3C DTD's and not a
mistake in TV." Another interesting one is "For example the W3C validator
doesn't check the value of attributes and so will report success even when
your page has many mistakes."

Can anyone confirm whether xml:lang="" is valid or not? The XML 1.0 [6] says
it's valid but I'm not sure if this applies to XHTML+RDFa. Is the last claim
regarding the W3C validator reporting success on invalid markup true?

Steph.

[1] http://drupalrdf.openspring.net/
[2]
http://validator.w3.org/check?uri=http%3A%2F%2Fdrupalrdf.openspring.net%2F&charset=%28detect+automatically%29&doctype=Inline&group=0
[3] http://drupal.org/node/769902
[4] http://www.totalvalidator.com/support/issues.html
[5] http://www.w3.org/TR/rdfa-syntax/
[6] http://www.w3.org/TR/REC-xml/#sec-lang-tag