<parttree>
    <part partid="0" name="car">
        <part partid="1" name="engine">
            <part partid="3" name="piston"/>
        </part>
        <part partid="2" name="door">
            <part partid="4" name="window"/>
            <part partid="5" name="lock"/>
        </part>
    </part>
    <part partid="10" name="skateboard">
        <part partid="11" name="board"/>
        <part partid="12" name="wheel"/>
    </part>
    <part partid="20" name="canoe"/>
</parttree>