Conflicting business rules identified. At each branch, cars, classified by car group, are available for rental. Branch has available cars. Cars are classified by car group. Term Definitions 4.
Most rentals are by advance reservation.
Reservations can be made for some cars for a specific future date. The rental period and the car group are specified at the time of reservation. Reservation, rental period, time of reservation, advance reservation. A customer can have several reservations but only one car rented at a time. A customer may have several reservations at one time.