Here you enter the customer code or use the PopUp feature (F4) to select a customer from the customer register.
It is possible to change customer code on an existing service order. A control question appears if the customer is changed allowing you to also change customer on the order rows. If you say OK to the question, the change will be saved to the order. In this mode it is also possible to change owner on the service object. Read more about change of owner in the help for the Update Product Register procedure.