What IS up with the search function? It would be super helpful!

As far as I know, the rules refer to the batter's box and not to batter's lines. Just like fair or foul, with no lines, we still have to call it.

mdntranger - I will also warn for that, but few players do that unless the pitcher is having a hard time getting the ball to the plate and they don't want to walk. If a pitcher is any good and sees a batter who wants to run up like that, they will pitch with a higher arc.