I've been using iDine for a while now. But I wonder how it "works".

1. I give my Visa credit card number and my frequent flyer number to iDine when I register.

2. I eat at an iDine restaurant and pay with the registered Visa credit card.

3. A few days later I get miles posted in my frequent flyer account.

What happens between 2 and 3? Are *all* credit card numbers sent to iDine to match with registered credit cards? Those that match get the miles earned? If that is the case, it seems there are some privacy issues (for those who are not enrolled).

Credit card use is for payment, not for frequent flyer miles if the user hasn't agreed to it.

Please note that I'm playing devil's advocate; I enjoy earning miles through iDine, but I really don't know how it works.