What does an order fill rate of 100% signify?

An order fill rate of 100% signifies that every incoming customer order was successfully filled as requested, meaning that customers received exactly what they ordered without any shortages. This metric is crucial for assessing the efficiency and effectiveness of inventory management and order fulfillment processes. A complete order fill rate indicates a high level of customer satisfaction and successful logistical operations, as it shows the business's ability to meet demand accurately.

In the context of the other options, while they might reflect aspects of operational success, they do not directly ascertain the fulfillment of customer orders in the way that the concept of an order fill rate does. For example, on-time shipment and error-free orders pertain to timeliness and accuracy but do not inherently confirm that all orders have been filled. Similarly, selling all products in inventory does not connect to how well customer orders were fulfilled. Thus, the essence of a 100% order fill rate lies specifically in its ability to indicate complete fulfillment of customer orders.