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/olap/LevelHandle.java
return getStringProperty( INTERVAL_BASE_PROP );
	}
	/**
	 * Returns the interval of this level. The return value is defined in
	 * <code>DesignChoiceConstants</code> and can be one of:
	 * 
	 * <ul>
	 * <li><code>INTERVAL_NONE</code>
	 * <li><code>INTERVAL_PREFIX</code>
	 * <li><code>INTERVAL_YEAR</code>
	 * <li><code>INTERVAL_QUARTER</code>
	 * <li><code>INTERVAL_MONTH</code>
	 * <li><code>INTERVAL_WEEK</code>
	 * <li><code>INTERVAL_DAY</code>
	 * <li><code>INTERVAL_HOUR</code>
	 * <li><code>INTERVAL_MINUTE</code>
	 * <li><code>INTERVAL_SECOND</code>
	 * <li><code>INTERVAL_INTERVAL</code>
	 * 
	 * </ul>
	 * 
	 * @return the interval value as a string
	 */
	public String getInterval( )
	{
		return getStringProperty( INTERVAL_PROP );
	}
	/**
	 * Returns the interval of this level. The input value is defined in
	 * <code>DesignChoiceConstants</code> and can be one of: