After you have sold your goods, for example after finishing with a sales contract, the sold goods need to be delivered to your customer. If you do not have the items you are selling in your store, you must create a purchase order for them.
For some reasons, spare parts may also be needed in stores. For example; a product may break while being stored in a store's warehouse.
In either case, you need to create purchase orders.
In the "Purchasing Management" menu, you can create purchase orders and manage approval processes for spare parts purchase orders.