How to distinguish a purchase order that has gone through a negotiation process?

Summary

How to distinguish a purchase order that has gone through a negotiation process?

Content

Hello,

Customer wants the requester of a non-catalog requisition to approve the purchase order generated as an outcome of a negotiation.

Let's suppose the following example:

Purchase order A:

 - Requester performs a non-catalog requisition

 - Buyer processes the non-catalog requisition into a negotiation

 - As an outcome of the negotiation, buyer creates a purchase order (A).

Purchase order B:

 - Requester performs a non-catalog requisition

 - Buyer processes the non-catalog requisition directly into a purchase order (B).

How can we distinguish purchase order A from purchase order B, so we can setup an approval workflow for purchase order A?