Different code-generation endpoints are used for different purposes: Code 128 for a meal's barcode image (used for both alphanumeric and UPC-A-digit barcodes, since Code 128 can render either), Code 39 for a generic order barcode, and a QR code (vCard-style, encoding the checkout's name/email/phone and an admin link) for a checkout. Bag, pickup, and delivery labels each have their own content list under Client Config's Labels settings, and "Barcode" is one of the items you can include or leave out of that list.