How many combinations of heads up action are there?

[ZeeJustin]

Let's say the cards don't matter, or perhaps they are already known. How many different ways are there that a heads up hand can be played?

Lets assume it's heads up, player X posts the SB, and player Y posts the BB. The SB is also the button.

1 possible combination would be, X raises, Y folds.
Another combination would be, X calls, Y checks. Y bets the flop, X raises, Y folds.
Etc.

How many of these combinations are there total?

Edit: Assume each player has over 12x BB, and the 4th bet is a cap, like on party.