A$2$Z Caterers $($A$2$Z$)$ is a catering firm with twenty employees that caters to office parties with $20$ to $50$ people each. To keep up with the growing business owner Liz Warren wants to install a new information system for managing the ordering and buying process. A$2$Z has a set of $15$ standard menus. When potential customers call, the receptionist describes the menus to them. If the customer decides to book a party order, the receptionist records the customer information $($name$,$ address, phone number, etc.$)$ and the information about the party $($e$.$g$.,$ place, date, time, standard menus, their quantities and total price$)$ on a contract. Typically, a party order includes multiple menu items in varying quantities. The customer is then faxed$/$emailed a copy of the party order. The customer must sign and return the party order along with a deposit before the party order is officially booked. The remaining money is collected when the food is delivered. The business accepts credit cards and checks for all payments. The system should maintain a bill of materials $($i$.$e$.,$ quantities of food items required for preparing each menu item$)$ to help estimate the food item requirements. Each week, the owner looks through the party orders scheduled for the week and places purchase orders for food items $($e$.$g$.,$ bread, chicken$)$ and supply items $($e$.$g$.,$ plates$)$ needed to make them. The business maintains a list of vendors and purchase orders are placed on these vendors. The owner would like to use the system for marketing as well. The system should help track how customers learned about A $2$ Z and identify repeat customers so that A $2$ Z can mail promotions to them.