What does the check availability option on the Staff settings page effect?
When adding a new event, or editing an existing event form, under the Staff tab there is a button for checking employee availability for a given date. When you click on this button a new window opens in another tab. In this window a list of active employees is displayed. This option affects whether a given employee shows up on this list. This is useful if you have an internal salesperson that does not go out and do events.