precedence of xml:lang and lang?

Mike, Hixie

the RDFa WG has an open issue (ISSUE-10 [1]) on the relative priority of
@lang and @xml:lang. RDFa 1.1 plans to allow the usage of @lang but one
has to define which of the two take precedence, in case both are present
on an element with different values.

XHTML1.0 has a clear statement on that[2] in Appendix C7:

[[
Use both the lang and xml:lang attributes when specifying the language
of an element. The value of the xml:lang attribute takes precedence.
]]

(RDFa would not advice to use both attributes, as in XHTML1.0, but the
precedence issue is relevant.)

I tried to look at the (X)HTML5 document, I did find a reference to
xml:lang in 7.03[3], but I did not find any reference to the question of
relative precedence. I must admit I am not very familiar with the HTML5
document structure, so I may have missed it.

Can you help me out and tell me if (a) the HTML WG has a decision on
that and, if not, is it o.k. with the group if we follow the statement
in [2]?

Thanks

Ivan


[1] http://www.w3.org/2010/02/rdfa/track/issues/10
[2] http://www.w3.org/TR/2000/REC-xhtml1-20000126/#guidelines
[3] http://dev.w3.org/html5/markup/common-attributes.html#common.attrs.xml

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