You can create SKUS for Product that don't usually have a barcode such as Deli or Menu items. The SKU will need to start with the number 4
A 12 digit SKU that starts with 4 is an entire block of barcodes that is reserved for a store to use internally - manufacturers are not allowed to use them on products for public sale (outside of the chain).
I recommend the following way to make custom barcodes for your store - it is the official way to do it and will work on any POS system in the world:
Create a new product with normal settings (Name/Department/Price)
For the SKU Start w/ a 4
Pick a sequential number (i.e. Brownie Bites would be say #1 internally)
Pad the barcode to that number up to 11 digits (so same example, Brownie Bites would be 40000000001)
Press the "Add Check-Digit" button for the system to auto-calculate a check digit and complete the barcode.
Your final barcode (for this example) would be: 400000000015
If you followed the above instructions, your barcode when printed will scan on any POS system (including the Passport - not just the Commander) as long as you add it to the price book.