https://supportcenter.devexpress.com/ticket/details/t633993/schedulercontrol-how-to-get-old-start-and-end-times-of-an-appointment-in-the
SchedulerControl - How to get old Start and End times of an Appointment in the AppointmentChanging...
May 10, 2018 - This seems like a gimme, but I cant find it anywhere. When a user changes the date of an appointment, we have to keep a log of the change.