The Salesperson field displays the Customer's Salesperson. A Salesperson is a Clerk. The term "Salesperson" is used when attributing sales to a Clerk. If a Salesperson not assigned to the Customer Database record, the default Salesperson value of 0 is used which defines the current Clerk as the Salesperson.
Unless a Salesperson is assigned to a Sales Transaction using the Salesperson field on the Complete Sale screen, assigned to the Customer attached to the Sales Transaction by the Customer's Database record, or assigned to a line item on the Sales Transaction using the Salesperson field on the Line Item Detail Screen, the Clerk who started the Sales Transaction is also the Salesperson.
See:
Customer Database - Main Screen Fields