confimation control key - return delivery
I want to do a return delivery to my vendor, making a delivery.
So I have done, with MIGO TCode, a return delivery, marking flag "VIA DELIVERY", is it right?
But, in my system was implemented the OSS note 589422: so I must insert a confirmation control key in the purchase order if I want to do a return delivery "via delivery"...
Can someone explain to me why I have to insert a confirmation control key??? I don't understand because the system need of a confirmation control key
Thanks in advance.