Probably an amateur question but I'm new to DBA (classic). Is there any way of printing the customer's item number on a traveler?

Again, please bear with me as I may not know the proper terminology. We enter a sales order based on customer item #. The sales order gets converted to a work order. When the traveler is printed, cust name, address, our item #, etc. are automatically placed on the traveler. There is a spot on the traveler form for cust item # but there is no code to pull data like there is in the other fields. Do I need to put in a code there and if so, what code?
 
Thanks