Case: Holloway Travel Vehicles
Holloway Travel Vehicles sells new recreational vehicles and travel trailers. When new vehicles arrive at Holloway Travel Vehicles, a new vehicle record is created. Included in the new vehicle record is a vehicle serial number, name, model, year, manufacturer, and base cost.
When a customer arrives at Holloway Travel Vehicles, he or she works with a salesperson to negotiate a vehicle purchase. When a purchase has been agreed to, a sales invoice is complete by the salesperson. The invoice summarizes the purchase, including full customer information, information on the trade-in vehicle (if any), the trade-in allowance, and information on the purchased vehicle. If the customer requests dealer-installed options, they will be listed on the invoice as well. The invoice also summarizes the final negotiated price, plus any applicable taxes and license fees. The transaction concludes with a customer signature on the sales invoice.

Deliverable #2
Develop a list of attributes for each of the entities. Each invoice will list just one customer. A person does not become a customer until he or she purchases a vehicle. Over time, a customer may purchase a number of vehicles from Holloway Travel Vehicles.
• Every invoice must be filled out by only one salesperson.
• A new salesperson may not have sold any vehicles, but experienced salespeople have probably sold many vehicles.
• Each invoice only lists one new vehicle.
• If a new vehicle in inventory has not been sold, there will be no invoice for it. Once the vehicle sells, there will be just one invoice for it.
• A customer may decide to have no options added to the vehicle, or may choose to add many options. An option may be listed on not invoice, or it may be listed on many invoices.
• A customer may trade in no more than one vehicle on a purchase of a new vehicle.
• The trade-in vehicle may be sold to another customer, who later trades it in on another Holloway Travel vehicle.