The Require Purchase Order field may be enabled to ensure that the Clerk enters the Customer's Purchase Order Number in the Order No. field on the Complete Sales Screen during a Sales Transaction.
If Req PO is enabled, a Purchase Order Number must be entered in the Order No field for each of the Customer's Sales Transaction. If the Order No field is not completed, the "This customer requires the Order Number field to be filled out" message is displayed and the transaction may not be completed until the PO Number has been entered.
If Req PO is disabled, a Purchase Order Number is not required to complete the Sales Transaction.
See:
Customer Database - Main Screen Fields