Final answer:
A purchase order is the source document used to request goods from a supplier, following an internal purchase requisition and leading to a shipping notice upon dispatch.
Step-by-step explanation:
The source document used to request goods is a purchase order. This document is issued by a buyer to a seller, indicating types, quantities, and agreed prices for products or services. It serves as an authorization tool for the purchase of goods and often follows a purchase requisition, which is an internal document that a company uses to request authorization for a purchase order.
Once the requisition is approved, a purchase order is generated and sent to the supplier. The supplier will then fulfill the order and send a shipping notice when the goods are dispatched. In contrast, a sales order is a document received by a business when a customer places an order for goods or services.