gradientUnits

<attribute name="gradientUnits" use="optional">
  <!-- @@ need to add more attributes here @@ -->
  <simpleType>
    <restriction base="string">
      <enumeration value="userSpaceOnUse"/>
      <enumeration value="userSpace"/>
      <enumeration value="objectBoundingBox"/>
    </restriction>
  </simpleType>
</attribute>