Generally, in the document flow, i see the sales order, delivery, picking (TO's if WM managed), PGI, and billing. However, for this particular sales order, there is a "Confirmation of Services" step in the document flow in between the delivery and invoice steps. What is this process? It does not seem to be related to service items because the sales order contains header level BOMs and their respective item level BOMs and they all have a quantity of 1 or more, and are storage location or warehouse managed. So, they do not look like services. There also doesn't seem to be a document that exists for this step.
Please, enlighten me on what this step does and why/why not it's useful.