Hi Werner Plumot
Yes you can change the linetypes of the legend to a dash-dot or any other pattern.
IChartSerie serieOne = shape.Series[0];
serieOne.DataPoints.DefaultDataPoint.DataFormat.LineProperties.LinePattern = ExcelChartLinePattern.Dash;
I have even attached a Sample Please check it for more details.
Sample:
ChartSerie.zipThanks for using XlsIO.
With regards,
Chella.