batter box
 

I responded to an umpire's question with this:
The front corner of the batter box is fair ground.
The only time it is not treated as fair is the exception for a batted ball hitting the batter or bat in her hands while still in the box.
I believe "still in the batter box" means neither full foot touched the ground outside the box.

Any comments?

7 - BATTING OUT OF THE BATTER’S BOX
To call a batter out for batting out of the batter’s box, one foot or both feet must be on
the ground completely outside the lines of the batter’s box when contact is made with
the ball. The lines of the batter’s box are considered inside the batter’s box.
A batter should be called out immediately for hitting a pitched ball while out of the bat
ter’s box, or for re-entering the batter’s box and making contact with the ball. The ball
is dead, and the batter is out whether the ball is fair or foul. When there are no batter’s
box lines, good judgment should be used and the benefit of doubt should go to the
batter. If contact is not made with the ball, there is no penalty.

Exactly.