The Updates, Reviews, Dates tab shows you updates, reviews and all the dates associated with this event. Updates and Reviews have icons with an A (for addendum) and dates have icons with a D.
You can peform the usual editing operations on these items such as editing their properties in a form, deleting them, and so on. You can also create new ones using the drop-down box. EvDocAdder is an update/review object and EvDocDate is a date object.