This button subtracts 10 milliseconds by default from the cycler timer. This is really not needed anymore because of the 3 different timers being used now but I still left it in. The subtracted time is from any added time that came from the user or automatically added due to PRE's. If all the added time is subtracted then you will be left with the regular timer. You can also change the number of milliseconds to be subtracted with this button in the Options/Timers menu.