<schemalist>

  <schema id='base'>

    <key name='foo' type='s'>

      <default>'bar'</default>

    </key>

    <key name='ranged' type='i'>

      <range min='0' max='22'/>

      <default>10</default>

    </key>

    <key name='choice' type='s'>

      <choices>

        <choice value='a'/>

        <choice value='aaa'/>

        <choice value='aaaaa'/>

      </choices>

      <default>'aaaaa'</default>

    </key>

  </schema>

  <schema id='sub' extends='base'>

  </schema>

  <schema id='sub2' extends='base'>

    <override name='foo'>'baz'</override>

    <override name='ranged'>0</override>

    <override name='choice'>'aaa'</override>

  </schema>

  <schema id='sub3' extends='sub2'>

    <override name='foo'>'foo'</override>

  </schema>

</schemalist>