In the events overview / list in the calendar dashboard you can see three types of events.

• An event created by you or another user.
• A repeat / recurring event.
• An external event.

An external event originates from another calendar system and is constantly synced with your calendar. Click the drop down just above the calendar in the calendar dashboard, click "Edit Calendar" in the drop down and scroll down to the "Import external calendars" section to see where the external event(s) originates from. External events cannot be created / edited / deleted using CalendarX.