To communicate how a purchase order gets approval, flowcharts like this one can be useful because they show every step of the process.
Text in this example:
Purchase Order Approval Process
Obtain Completed Credit Application
PO & Credit Application to Controller for Approval
P.O. from non-existing customer
Company in the US or Canada
Request other Payment form
Does customer have any unpaid P.O.
Project completion certified
PO to Controller for Approval