1<map id="Graphical Class Hierarchy" name="Graphical Class Hierarchy"> 2<area shape="rect" id="node1" href="$class_qwt_series_data.html" title=" " alt="" coords="5,5,196,47"/> 3<area shape="rect" id="node2" href="$class_qwt_array_series_data.html" title=" " alt="" coords="244,5,401,47"/> 4<area shape="rect" id="node3" href="$class_qwt_interval_series_data.html" title="Interface for iterating over an array of intervals." alt="" coords="449,13,604,39"/> 5</map> 6