Definicja firmly book (PE)

To change the status of a business event from "planned" to "active" and to establish the definitive attendee list.

Note:

You can create an event in "planned" or "active" status. The event must be in "active" status before you can bill attendees or do follow-up processing for the event.

When the event is firmly booked, you can specify that the automatic correspondence function triggers notifications for the attendees, such as definite confirmation of place.