Is this call reversible?

[Dakota]

Fair or foul is never appealable; you should avoid even the appearance of an appeal being successful.

Having said that, calling a foul ball fair is always reversable, because the correct call (foul) is a dead ball, so nothing can happen. Put the runners back on their bases, make the proper call on the batter (strike or count stays at x-2, depending), and proceed.

Calling a fair ball foul is almost never reversable, since either the offense or the defense will almost certainly react to the call, and it will be difficult / impossible to place the teams in the situation they would have been in with the correct call. 99.999% of the time, ya gotta live with the call.