The PassKit Portal allows you to choose from the available Barcode encoding formats, and will adjust the Pass layout accordingly. You provide a message that will be encoded within the Barcode. This can be:
Unique to each Pass - you would use this for a Membership Card, a Loyalty Card, an Event Ticket, a Boarding Pass, or a Store Valued Card. Basically anywhere you want to identify the individual Pass holder or;
Common for each Pass - you might use this a coupon where you just need the SKU (Stock Keeping Unit) number embedded in the barcode so it can be recognised by the Point of Sale.
The message encoded in the Barcode is just data, there’s nothing that limits you from using it to carry additional information.
For example, suppose you need to scan a pass when network access is not possible (perhaps onboard a ship). This would make it impossible to communicate with the PassKit server in real time. You can sign the data you need with a private key, and use the result as a barcode. Although this approach doesn’t let you impose a one-time-use pass, it could be useful where passes are valid for a predictable period of time.
Optionally you can include alternate text that is displayed immediately below the barcode. You can enter whatever you want here but it’s common to display the barcode number, or the unique identifier that you want your staff to key in to the Point of Sales terminal, just in case the scanning equipment doesn’t work.