Ability to capture Notes on approved Purchase Order

Summary

Ability to capture Notes on approved Purchase Order

Content

Hello Friends,
I do NOT find any where to capture Notes on approved Purchase Order .DO NOT WANT TO REVISE PO.
Customer is looking for a place holder to capture misllaneous notes once PO , once it is approved.
Is this true?
What is the workaround for this? I am sure other customer would also be facing this issue? How other customer is handling this?