To run a macro when the NotInList event occurs, set the OnNotInList property to the name of the macro.
Remarks
You can use a NotInList macro to add a new value to the combo box list. When the NotInList event occurs, open a custom dialog box and set the value of one of its controls to the new value. This control should be bound to the field in the table or query that is the source for the combo box. Save the record in the custom dialog box, then requery the combo box.
You can't use the CancelEvent action in a NotInList macro.