The document provides training on out-of-stock (OOS) issues for Jumia vendors. It defines OOS, outlines Jumia's shipping and order fulfillment processes, and discusses the key causes of OOS including lack of inventory and order cancellations. The document also explains the impacts of OOS such as penalties, lost sales, and potential de-listing. It provides recommendations for vendors to avoid OOS through proper inventory management, order scheduling, and responding promptly to system errors.