That will vary. It can technically include any text up to a limit, but most likely it will be a URI, but it could be as simple as and account number. You would want to decode the QR (you can likely do that using your phone camera) and that would be the data to enter.
Ideally this tool would simply use the camera to capture the visual code (bar, QR, etc.) and enter it/replicate it.
agree. implemented QR code scanning using the great html5-qrdecode package so scanning happens locally.