Pitcher warm-up area during infield practic?

[BuggBob]

NFHS Rules. Home team takes their infield practice before the game, when they are done the visitors start. The home team catcher comes out to the ondech circle, sets up a Green -yello-red practice plate , wile the pitcher sets up in the coaches box area. Two girls form a wall around the catcher while the coach does the same for the pitcher. I ask them all to move to some other area while the other team takes their turn at practice. Before the game home coach asks me why I asked them to move, he tells me that of the four home games he has had none of the other umpire (including may current partner) have asked him to move. I can not recite a rule, but thank him for moveing and that I will look it up. You good umpires are that look up, since my books are in the car, it's raining, and I'm still in my bathrobe.

Is there a rule that resticts where a pitcher can warm up before a game?

Thanks
Bugg