code: function _calculateStartDate(oDate) {
  
  		var sIntervalType = this.getIntervalType();
  		var oUTCStartDate = CalendarUtils._createUniversalUTCDate(oDate, undefined, true);
  
  		switch (sIntervalType) {
  		case CalendarIntervalType.Hour:
  			oUTCStartDate.setUTCMinutes(0);
  			oUTCStartDate.setUTCSeconds(0);
  			oUTCStartDate.setUTCMilliseconds(0);
  			break;
  
  		case CalendarIntervalType.Day:
  		case CalendarIntervalType.Week:
  		case CalendarIntervalType.OneMonth:
  			oUTCStartDate.setUTCHours(0);
  			oUTCStartDate.setUTCMinutes(0);
  			oUTCStartDate.setUTCSeconds(0);
  			oUTCStartDate.setUTCMilliseconds(0);
  			break;
  
  		case CalendarIntervalType.Month:
  			oUTCStartDate.setUTCDate(1);
  			oUTCStartDate.setUTCHours(0);
  			oUTCStartDate.setUTCMinutes(0);
  			oUTCStartDate.setUTCSeconds(0);
  			oUTCStartDate.setUTCMilliseconds(0);
  			break;
  
  		default:
  			throw new Error("Unknown IntervalType: " + sIntervalType + "; " + this);
  		}
  
  		return oUTCStartDate;
  
  	}
docs: /*
  @param {object} oDate JavaScript date object
  @returns {UniversalDate} Start date for date object