Stop PO users from Directly updating the Account Codes

Summary:

Users are able to update teh Account codes on a PO (provided there is no limiting down stream activity (invoicing / recepiting). Customer would like to know if they can stop this

Content (please ensure you mask any confidential information):

Customer has an issue whereby users are able to update the account codes on PO's. This can lead to reporting being incorrect if they report on category code, as the account codes can have been changed without a corresponding change to the Category Name. In order to stop this, the customer would be interested in a "requisition" like scenario whereby the account codes are reverted in all cases if changed on the requisition (excluding the potential for the Cost Center Override option).