Have you ever been issued a "guaranteed" reservation by a hotel? You know the drill: they take a credit card number and tell you that you will be charged for the room if you don't show up. But in return, you comfort yourself with the assumption that your access to an actual room at that particular hotel is "guaranteed" even if you show up at 4 AM. Maybe if you did this, you assumed that it meant that the hotel had already sold the room to you, and that, barring acts of God like a tornado, no matter how late...