:lang, xml:lang vs. lang

Ignore this test. (:lang with xml:lang is not supported)
You can only get meaningful results for this test if :lang works with both lang and xml:lang attributes.

Assertion: When an xml:lang attribute and a lang attribute on the same element have different values, the xml:lang value will match :lang for pages served as application/xhtml+xml.

Notes:You can only get meaningful results for this test if :lang works with both lang and xml:lang attributes. If :lang does not work with xml:lang, the test should show a message "Ignore this test." You should ignore the instructions and test results that follow and mark the results as "not applicable".