The OP mentioned "shipment document" and automatic PO.
Yes, but should we have to read 3 times and guess? The title is also misleading, so when the next person comes here looking for purchase order type determination outside the context of shipment costs, it will lead to confusion.
Many times we waste times in threads trying to guess what the OP means, which leads to garbage and confusion. It is my personal opinion that we shouldn't try to guess, it's the obligation of the OP, the one who wants help, to take the time to explain the issue clearly.