Simple (former Default) Appointment Editing Form
The Simple (Default) appointment editing form is an instance of the AppointmentForm class. The form used to be a default appointment editing dialog of the WinForms Scheduler before version 15.2 when it was replaced with the Outlook Appointment Editing Form.
To add controls used to display and modify appointment custom fields or to customize the editing form in a different manner, use the Custom Form Assistant in the Visual Studio Designer.