() { el.setAttributeNS(XMLNS, "a:xmlns", "fail") })
  assert_throws_dom("NAMESPACE_ERR",
                    function() { el.setAttributeNS(XMLNS, "b:foo", "fail") })
}, "The XMLNS namespace should require xmlns as prefix or qualified name")
test(function() {
  var el = document.createElement("foo")
  el.setAttributeNS(XMLNS, "xmlns:a", "pass")
  assert_equals(el.attributes.length, 1)
  attr_is(el.attributes[0], "pass", "a", XMLNS, "xmlns", "xmlns:a")
}, "xmlns should be allowed as prefix in the XMLNS names