[Bug 16190] Polyglot Markup: Clarify that xml:lang is optional

https://www.w3.org/Bugs/Public/show_bug.cgi?id=16190

--- Comment #3 from Leif Halvard Silli <xn--mlform-iua@xn--mlform-iua.no> 2012-03-25 01:23:55 UTC ---
(In reply to comment #2)
> I don't believe this is appropriate. See my rationale in comment 7 at
> https://www.w3.org/Bugs/Public/show_bug.cgi?id=16166

I don't think your justification there is good enough.

(1) The point is that if one is to make an application/xhtml+xml document, then
one isn't required to use xml:lang, if all one cares about is XML-capable
HTML5-parsers.

     And so, the question begs to be asked: Why must I, suddenly, use xml:lang,
it the document
     is supposed to be 'polyglot'? 

     I agree that you, in bug 16166, 7th comment, have pointed out some reasons
why an author might want the document to contain xml:lang.  But I see no *must*
in there - it all depends on how "naked" you expect the XML parser to be.

(2) Meanwhile, in 16166, you suggest that text/html parsers should start to
handle xml:lang. So, if that proposal were to be accepted, how would this
impact on Polyglot Markup? My presumption is that you would like to be able to
produce polyglot markup which contained xml:lang, without any requirement that
@lang is present. 

(3) HTML+RDFa 1.1 is agnostic about xml:lang versus lang
     http://www.w3.org/TR/rdfa-in-html/#additional-rdfa-processing-rules

(4) RDFa Core likewise says:  "In XHTML+RDFa [XHTML-RDFA], for example, the XML
language attribute @xml:lang or the attribute @lang is used to add this
information, whether the plain literal is designated by @content, or by the
inline text of the element:" 
   http://www.w3.org/TR/2011/WD-rdfa-core-20110331/

And so, I maintain that xml:lang should be optional. It would also be good to
point out when/for what xml:lang is useful.

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Received on Sunday, 25 March 2012 01:23:59 UTC