Unblock/delete indicator in Pur.Order - authorization object

Hello,

I need to acomplish the closing of PO items after being open (without Goods Receipt) for more than six months. I want to do this using the "Lock" button in the PO-item. (The "final delivery flag" does not actualy "close" the POitem as I can still do a goods receipt!).

The question is, ones closed a PO-item, I want to acompish that only certain users can "unblock" the Item if necesary.

I want to know if there exists an authorization object asociated with this "unluck button" in the PO-Item?

If not, is there another way how to tackle this problem?

Thanks for any reply.

Aart