chromium/src/third_party/blink/web_tests/css3/selectors3/xml/css3-modsel-57.css

@namespace a url(http://www.example.org/a);
@namespace b url(http://www.example.org/b);
*|p, *|q, *|r { display : block ; margin-bottom : 1em }
*|p, *|r { background-color : red }
div.stub *:not([a|title]) {background-color : lime }