diff --git a/Examples/33chartcreate-pie.php b/Examples/33chartcreate-pie.php
index 44910f9c..5af02905 100644
--- a/Examples/33chartcreate-pie.php
+++ b/Examples/33chartcreate-pie.php
@@ -87,7 +87,7 @@ $dataSeriesValues1 = array(
 //	Build the dataseries
 $series1 = new PHPExcel_Chart_DataSeries(
 	PHPExcel_Chart_DataSeries::TYPE_PIECHART,				// plotType
-	NULL,			                                        // plotGrouping
+	NULL,			                                        // plotGrouping (Pie charts don't have any grouping)
 	range(0, count($dataSeriesValues1)-1),					// plotOrder
 	$dataSeriesLabels1,										// plotLabel
 	$xAxisTickValues1,										// plotCategory
@@ -161,7 +161,7 @@ $dataSeriesValues2 = array(
 //	Build the dataseries
 $series2 = new PHPExcel_Chart_DataSeries(
 	PHPExcel_Chart_DataSeries::TYPE_DONUTCHART,		// plotType
-	NULL,			                                // plotGrouping
+	NULL,			                                // plotGrouping (Donut charts don't have any grouping)
 	range(0, count($dataSeriesValues2)-1),			// plotOrder
 	$dataSeriesLabels2,								// plotLabel
 	$xAxisTickValues2,								// plotCategory
diff --git a/Examples/33chartcreate-radar.php b/Examples/33chartcreate-radar.php
index d0e2b9fa..b8b427f3 100644
--- a/Examples/33chartcreate-radar.php
+++ b/Examples/33chartcreate-radar.php
@@ -98,7 +98,7 @@ $dataSeriesValues = array(
 //	Build the dataseries
 $series = new PHPExcel_Chart_DataSeries(
 	PHPExcel_Chart_DataSeries::TYPE_RADARCHART,				// plotType
-	NULL,													// plotGrouping
+	NULL,													// plotGrouping (Radar charts don't have any grouping)
 	range(0, count($dataSeriesValues)-1),					// plotOrder
 	$dataSeriesLabels,										// plotLabel
 	$xAxisTickValues,										// plotCategory