Again thanks for all the help so far ... turns out that LineSeries.RenderData is a protected property
renderData property renderData:Object [read-only] Stores the information necessary to render this series. Implementation protected function get renderData():Object ... so I presume I have to subclass LineSeries to make it publicly available which gives errors on both attempts: package { import mx.charts.series.LineSeries; public class myLineSeries extends LineSeries { // overriding a function not marked for override // incompatible override public function get renderData():Object{ return super.renderData; } // incompatible override override public function get renderData():Object { return super.renderData; } } } Would appreciate any pointers. TIA, Mic.