Assertion: When the :lang value uses a single subtag, it will not match against an attribute value where it appears in a different position.

Notes:
You can only get meaningful results for this test if :lang works with lang, since it checks a detail with regard to that support. If :lang does not work with 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".