Bug 132031 access to chart scripting methods and related documentation
It's very strange that access to chart scipting methods available only from script tab related to whole chart item. This approach is not consistent comparing to how script defined for such report items as table or dataset. That why inside of chart's script tab we see comment out bunch of chart scripting methods. I suggest that every component on chart item that have corresponding scripting methods must have separate script tab with set predefined methods. Beside that it would be nice to have at least some documentation and axamples on this topic.
chart/org.eclipse.birt.chart.engine/src/org/eclipse/birt/chart/internal/datafeed/GroupingLookupHelper.java
if ( bBaseGroupEnabled )
		{
			String strBaseAgg = baseSD.getGrouping( ).getAggregateExpression( );
			boolean bOrthoGroupEnabled = orthoSD.getGrouping( ).isEnabled( );
			strOrthoAgg = bOrthoGroupEnabled ? orthoSD.getGrouping( )
					.getAggregateExpression( ) : strBaseAgg;
		}
		return strOrthoAgg;
	}
	/**
	 * Simply gets aggregation expressions for the series definitions. If
	 * grouping is not enabled, return null
	 * 
	 * @param sd
	 *            series definition
	 * @return aggregation expressions for the series definitions, or null if
	 *         grouping is disabled.
	 */
	static String getAggregationExpression( SeriesDefinition sd )
	{
		SeriesGrouping grouping = sd.getGrouping( );
		if ( grouping.isSetEnabled( ) && grouping.isEnabled( ) )
		{
			return grouping.getAggregateExpression( );
		}
		return null;
	}
	/**
	 * Gets aggregation expressions of orthogonal series definition. If base
	 * series doesn't enable grouping, return null. If its own grouping is null,