Bug 189363 The aggregation of table should be start with sigma symbol
Description: Follow the spec, after specify a aggregation on a table, the aggregation should be represented by starting with the sigma symbol
xtab/org.eclipse.birt.report.item.crosstab.ui/src/org/eclipse/birt/report/item/crosstab/internal/ui/editors/action/AddSubTotalAction.java
newOperation.setLevelHandle( newInfo.getLevel( ) );
			}
			else if ( !oriOperation.isSameOperation( oriInfo ) )
			{
				processOperation( oriOperation, newOperation );
				oriOperation = new SubOpration( );
				oriOperation.setLevelHandle( oriInfo.getLevel( ) );
				newOperation = new SubOpration( );
				newOperation.setLevelHandle( newInfo.getLevel( ) );
			}
			oriOperation.addInfo( oriInfo );
			newOperation.addInfo( newInfo );
			if ( i == ori.size( ) - 1 )
			{
				processOperation( oriOperation, newOperation );
			}
		}
	}
	private void processOperation( SubOpration oriOperation,
			SubOpration newOperation ) throws SemanticException
	{
		if ( oriOperation.getMeasures( ).size( ) == 0
				&& newOperation.getMeasures( ).size( ) == 0 )
		{
			return;
		}
		if ( oriOperation.getMeasures( ).size( ) == 0
				&& newOperation.getMeasures( ).size( ) != 0 )
		{
			addAggregationHeader( findLevelViewHandle( newOperation.getLevelHandle( ) ),