Standard Commitment In PSI

Hi All

One question on Project Commitment Standard Behaviour.

The standard PSI commitments view also includes unapproved and approved requisitions and unapproved purchase orders. 

Assume we have an Approved Purchase order and we have not received the PO.

A new revision of the purchase order is created to add 1 additional item at 100 each. The purchase order status changes to unapproved and the new revision of the purchase order is routed for approval.

Will the commitment amount will correspond to the last approved revision of the purchase order.

Is this standard behaviour, we would expect that if a new unapproved revision of the purchase order is created until the new revision of PO is approved, the cost should not disappear entirely from the projects commitments.