The system creates a bill. There is a return with a given confirmation number. There is a vehicle with a given license number. An instance of bill is created. An instance of work order is created.
Return is linked to bill.
Vehicle is linked to work order. Preparation includes car wash, fuel fill, and minor repairs such as bulb replacements. There is a vehicle with a given license number. Instances of service invoices are created. Vehicle is linked to service invoices.