Can someone explain how the confirmation reminder is triggered, because based on the help function in IFS a confirmation reminder will be created based on a specific days before delivery.

To my opinion it will be more useful to trigger based on a specific days after release a purchase order. Because you want to be sure a supplier received the purchase order and you want to have that the order is confirmed for delivery.
Is the option based on release purchase order possible to setup, or is this a hard coded IFS setting?
Thanks in advance,
Richard