This wknd we drew attention to a girl that hit the ball w one foot completely out of the box. Plate ump was brand new said he didn't see It. No problem with that. In between innings field ump who is more seasoned is explaining the rule but states as long as one foot is in the box its legal? I mention they call slappers a lot for stepping out and he said sometimes slappers have their back foot up and front outside the box so they don't have a foot in the bx. What's the correct rule? ASA rule set