A Date-Time expression that specifies the starting date of the inside zoom unit.
By default, the StartDate property indicates the date being
used when the Add method is called, or the
same as DateTime parameter of the InsideZoom
event. The EndDate property indicates the
ending date of the unit. If the chart's time scale is changed, the StartDate
and the EndDate of the InsideZoom objects are not changed accordingly to the
new base level.