Reserve invoice use case: Where the inventory reduction takes place until the warehouse delivers the product/order.

The Debt Invoice is that of a normal sale.

When using reservation invoices, a QR or other validator could be added to the invoice delivered to the customer so that this document can be scanned by the person making the delivery.

An example of companies that have both types of invoices is with Hardware Stores. Some invoice items must be picked up at warehouses in another location.