The Alternate Actor tab allows you to select another user to which this user’s work items can be reassigned. This reassignment can be performed on this tab as well (by selecting the Enable alternate actor checkbox), or it can be performed by the user through TaskManager. If a user does not have the security privileges to see another user object, then that user will not be available for alternate actor selection. Changes to the alternate actor status made on this tab are also displayed in TaskManager, and vice versa.
For more information, see the TaskManager guide.