A proforma invoice is a preliminary bill of sale sent to buyers in advance of a shipment or delivery of goods. It is often used to
declare the value of the trade. It is not a true invoice because it is not used to record accounts receivable for the seller and
accounts payable for the buyer. 'Cash with Order' means that the buyer pays when ordering the goods and they are dispatched
only after payment is received. Therefore, a proforma invoice is most appropriate for a 'Cash with Order' terms of sale.