The "Carrier" field is an optional field, you need not select any. The purpose is for you to specify a carrier if you are using one, for example, if you are not delivering a particular order yourself, and you have used DHL to send the cartridge to the customer instead, you can then select DHL as the "Carrier" and input DHL's tracking number in the next field.
If you don't use other carriers, then you may leave both "Carrier" and "Tracking Number" fields blank. You may also use the "Tracking Number" field to input your own internal delivery reference number to help you track deliveries if there's a need.
Are you able to advise how soon you can update all thoes open orders? There are almost 500 open orders now, please expedite, thank you.