REQUIRED: Develop an entity-relationship diagram of the Information System that supports the purchasing process of Proware Company described below. Include the cardinality constraints.

The individual departments of Proware Company refer to various vendor catalogs when they need to purchase items. They then complete a purchase request form over the company intranet for each vendor. Once completed, the form is forwarded to the Purchasing department, where it is validated and checked against the department's budget to ensure there are still funds available in its supply budget. Each form is assigned a unique serial number, referred to as the PO number. Purchasing transmits the validated form to the vendor, or faxes it if the vendor is not online.

When the vendor fills the order, it sends an invoice to purchasing and enclose a copy of the invoice with the shipment when it is delivered to the department. The department verifies that the contents match the PO, attaches a note approving payment, and forwards the approved invoice to purchasing. An invoice may only be partially approved, if an item was missing or incorrect. A second payment authorization may be submitted at a later time when the correct item is received.

Each week purchasing generates vendor checks based on the approved authorizations from departments, and maintains a copy of the check in the computer file. Vendors may be paid for multiple orders (e.g. for several departments) in any given week.

Each month, purchasing generates a budget report for each department, which itemizes the amount paid for each invoice, the amount allocated for outstanding purchase orders, and the remaining available funds for the department.