Bug 179674 Support time dimension in model
When define time dimension in model, the "itTime" property will be set. However this is not enough. We also need to know to what precision the time value should be evaluated, say, year, month, day, etc. Model needs to be enhanced to support such requirement.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/api/elements/DesignChoiceConstants.java
*/
	public static final String CHOICE_DATA_SET_MODE_TYPE = "dataSetMode"; 
	public static final String DATA_SET_MODE_SINGLE = "single"; 
	public static final String DATA_SET_MODE_MULTIPLE = "multiple"; 
	/**
	 * filterTarget -- filter target type.
	 */
	public static final String CHOICE_FILTER_TARGET = "filterTarget"; 
	public static final String FILTER_TARGET_DATA_SET = "DataSet"; 
	public static final String FILTER_TARGET_RESULT_SET = "ResultSet"; 
	/**
	 * View action --view action type.
	 */
	public static final String CHOICE_VIEW_ACTION = "viewAction"; 
	public static final String VIEW_ACTION_NO_CHANGE = "NoChange"; 
	public static final String VIEW_ACTION_CHANGED = "Changed"; 
	public static final String VIEW_ACTION_ADDED = "Added"; 
	public static final String VIEW_ACTION_DELETED = "Deleted"; 
	
	/**
	 * measure Function -- measure function type.
	 */
	
	public static final String CHOICE_MEASURE_FUNCTION = "measureFunction"; 
	public static final String MEASURE_FUNCTION_SUM = "sum"; 
	public static final String MEASURE_FUNCTION_COUNT = "count"; 
	public static final String MEASURE_FUNCTION_MIN = "min"; 
	public static final String MEASURE_FUNCTION_MAX = "max"; 
	
	/**