 "BottomDisplayStyleShiftDown Displaystyle om fraction");

    test(function() {
      assert_true(MathMLFeatureDetection.has_mspace());

      var v = 6000 * emToPx;
      assert_approx_equals(getBox("den0003").top - getBox("ref0003").bottom,
                           v, epsilon, "mfrac: denominator shift");
    }, "BottomShiftDown");

    test(function() {
      assert_true(MathMLFeatureDetection.has_mspace());

      var v = 4000 * emToPx;
      assert_approx_equals(getBox("den0004").top - getBox("num00