QUESTION: Study the following case, then prepare a context diagram and level zero diagram based on the case.

CASE: When parts are received from vendors, they are accompanied by an invoice. Mrs. Gauron in the Receiving Department checks the invoice against the order file to be certain that the correct parts were delivered. If the parts were not ordered or the order was incorrectly filled, the parts are returned. If the parts are correct, the inventory file is updated to reflect the new quantity for these parts. Mrs. Gauron then prepares the payment for the vendor. She also enters the payment transaction in the general ledger, which is maintained as a bound accounting ledger. A worker on the factory floor who needs a part requests it by submitting a requisition to the part clerk. The information on this form is used to update the inventory file. Each week, the part clerk uses the inventory file to prepare a report. For parts listed on the report, a purchase request form is prepared and sent to the purchasing office.