An event exit is a software routine your programmers have to write themselves. The HelpServer server engine invokes that routine the moment specific events occur on a data object in the HelpServer Workbench. At this moment invocation occurs on the the following events.
When a changed data object is saved.
When a data object changed by another author is saved.
When a data object is published.
It is up to you to determine what specific tasks your event exit should perform. For example, it could log or store data in one of your databases or pass some parameters to other applications. All the parameters your exit routine requires can be specified in the properties of the HelpServer data object. You can use as many event exists as you please.