Magento 2 - Why is there a “order number” field in checkout at payment method “Purchase Order”?

Question

If I select the payment method "Purchase Order" then a mandatory field shows where the customer has to enter a order number. Why?? And how does the customer know what he has to enter?!

This is a fresh magento 2.3.4 installation.

Answer 1

P.O. or Purchase Order number is a unique number assigned to a purchase order form. The purchase order details the products or services a business wishes to receive from a particular vendor (or supplier). The purchase order number will be referenced throughout the transaction process by both buyer and seller.

The purchase order number, usually found at the top of the form, will be referenced continuously throughout the transaction, such as in client phone calls, shipping forms and eventually the invoice.

An invoice is issued by the seller towards the end of the transaction, upon completion of the terms as outlined in the purchase order. The invoice is the bill. As with the purchase order, it will list the details of the products or services the seller delivered or provided, quantities and price. It will also reference the P.O. number to show that this transaction was pre-approved. Upon receipt, the buyer is expected to pay it within the terms previously agreed upon.