Originally Posted by auh2o
Correct. It is permissable but you would be on stand-by for the connecting flight without any confirmed flight and the risk if you get stuck is all yours.
This was always my understanding, but I have been denied when trying to get onto a direct flight when I was originally on a later connection (IND-DEN instead of IND-ORD-DEN). Of course, the last time I tried that was a couple years ago.