xml:lang="" vs meta Content-Language

Test passes if you see green below, and no message to ignore it.

This test is only valid if the user agent recognises the meta Content-Language and html xml:lang declarations, and :lang works.

Ignore this test. (:lang not supported) 

Assertion: If the meta Content-Language element contains a language declaration but the html element uses an empty xml:lang attribute, the UA will not recognize the language declared in the meta Content-Language element.

Notes:

Red means the HTTP had precedence.

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XHTML 1.1 as XML

language-declarations-017
Result summary & related tests