Rule 7-6-F

[rwest]

Rule 7 Section 6. The Batter is OUT

F. When a batter leaves the box, but has returned to the box and makes contact with the ball.


My question is this, define "leaves the box"? Do both feet have to be out of the box? Or is it just one foot? Also, does the entire foot have to be outside the lines? In otherwords, has the batter left the box, if a portion of one foot is touching the line?

Thanks!
Randall