By default, the EndDate is defined once the the Add method is called as being the end date of the unit as indicated by the base level in the chart. For instance, if the chart displays days, the StartDate indicate the date where the inside zoom unit start, and the EndDate where the date ends, in other words the next day of starting date. If the chart displays weeks,  the start date indicates where the week beings, since the EndDate indicates the end date on the week, in other words, where the next week begins. So, the EndDate property indicates the ending date of inside zoom unit, as specified by the base level ate the adding time. 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.