Girls Fastpitch slap hitting from left side

Question
I've noticed that girls who hit from the left side of the plate tend to run up and slap at the pitch in order to get on base. I found it interesting during the college womans world series that many of the girls looked to be or had at least one foot out of the box at time of making contact. What is the rule for being in the batters box?  

Answer
Hi Ed,

I watch the CWWS series every year.  I have a # of umpire friends who have worked that tournie (and the plate in the finals) and in 1996 I spent an entire week in that stadium for the advanced national umpire's school.

I know it appears they may be out of the box but if any part of the foot is touching any part of the line when they make contact they are in the box.  It is the lead foot we look at and if you look at the size of the box and the size of the foot, you have to be really out there to not have something touching something.

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