top,
                           v, epsilon,
                           "msqrt: vertical gap");
    }, "RadicalRuleThickness");

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

      var v1 = 6000 * emToPx;
      var v2 = 1000 * emToPx;
      assert_approx_equals(getBox("base0071").top - getBox("radical0071").top,
                           v1 + v2, epsilon,
                           "msqrt: vertical gap");
      assert_approx_equals(getBox("base0072").top - getBox("radical007