You can view the document status of quotations, purchase orders, packing slips, invoices, and reversed picking lists. By checking the document status against the purchase status, you can get a good idea of how far the purchase order has come in the purchase process. The document status changes each time one of the above-mentioned documents is printed or updated. An update of an invoice can thus be followed by an update of a packing slip, typically following a partial delivery or partial invoicing of the purchase order.