<Style filter-mode="first" name="style">
  <Rule>
    <Filter><![CDATA[([feature] = 'baz')]]></Filter>
    <ShieldSymbolizer face-name="Arial" file="test.svg" fill="#0000ff"><![CDATA[[refs]]]></ShieldSymbolizer>
  </Rule>
  <Rule>
    <Filter><![CDATA[([feature] = 'bar')]]></Filter>
    <ShieldSymbolizer face-name="Arial" file="test.svg" fill="#ff0000"><![CDATA[[refs]]]></ShieldSymbolizer>
  </Rule>
</Style>
