Bug 212291 SWT Chart render engine always uses 96 DPI(Display) resolution
chart/org.eclipse.birt.chart.engine/src/org/eclipse/birt/chart/computation/withaxes/PlotWithAxes.java
return new DataSetIterator( new String[]{
						"Category1", "Category2", "Category3" 
				} );
			}
		}
		return getTypedDataSet( sea[iSeriesIndex], iType );
	}
	/**
	 * @param se
	 * @param iType
	 * @return
	 * @throws ChartException
	 * @throws IllegalArgumentException
	 */
	protected final DataSetIterator getTypedDataSet( Series se, int iType )
			throws ChartException, IllegalArgumentException
	{
		DataSetIterator dsi = new DataSetIterator( se.getDataSet( ) );
		if ( ( dsi.getDataType( ) & TEXT ) == TEXT )
		{
			if ( ( iType & LINEAR ) == LINEAR
					|| ( iType & LOGARITHMIC ) == LOGARITHMIC
					|| ( iType & DATE_TIME ) == DATE_TIME )
			{
				throw new ChartException( ChartEnginePlugin.ID,
						ChartException.DATA_SET,
						"exception.text.data.numerical.datetime.axis",  
						Messages.getResourceBundle( rtc.getULocale( ) ) );
			}
		}