When a PO is raised it is said to be pending or active. This means changes it can be modified.

You should DEACTIVATE (Lock) Purchase Orders before you send them to suppliers to prevent additions and/or deletions which can cause confusion subsequently. Deactivating in effect freezes the Purchase Order.

If changes have to be made to a Purchase Order use the Reactivate command on the Purchase Order details form. This should only be done if you are sure the PO has not already been sent to the supplier.