ction.has_mspace());

      var v = 5000 * emToPx;
      assert_approx_equals(getBox("den0002b").top - getBox("ref0002b").bottom,
                           v, epsilon, "mfrac: denominator shift");
    }, "BottomDisplayStyleShiftDown Displaystyle");

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

      var v = 5000 * emToPx;
      assert_approx_equals(getBox("den0002c").top - getBox("ref0002c").bottom,
                           v, epsilon, "mfrac: denominator shift");
    },