Which term indicates the date by which a required delivery should occur?

The term that indicates the date by which a required delivery should occur is known as the Required Delivery Date. This date is crucial in supply chain and logistics management, as it ensures that the items or supplies are delivered on time to meet operational needs. Having a specified delivery date helps in planning and resource allocation, ensuring that the supply chain remains efficient and effective.

In contrast, the other terms have different meanings related to logistics and supply management: the Source of Supply refers to the organization or vendor that provides the needed items; the National Stock Number is a unique identifier assigned to items for logistical tracking; and the Last Known Holder refers to the last entity or person known to possess a particular item. Each of these terms serves specific functions within the supply chain, but they do not denote a specific deadline for delivery.