As many line items as desired can be added, capturing things like handling instructions, miscellaneous contact information, separate bill to details, or just miscellaneous notes.
Line items print out on the Order Printout report, and also are reported on all Data Analysis cubes that show line item detail -- it may not be terribly important to see a customer's preferred method of shipping in the details of a data analysis, but it is there in case it is help to you.