If you pay to customer account in POS, the sales order is invoiced either by the transactional statement or by the Real-time service. This is not always the preferred result. Customers, both B2B and B2B, often has different demands on how and when to be invoiced. It's therefore a better solution to post a packing slip instead. The invoicing can then be performed by the business rules manually or in batch. Invoicing directly or not could be controlled by a parameter.