Jump Ball Positioning

[Loudwhistle]

BV I'm getting ready to toss to start the game. I blow my whisltle and step into the circle and before I toss it up partner blows whistle and runs over and tells a player on the outside of the big circle that he can't have his foot behind an opponents foot during the jump. Basically, a home player was just outside the circle and a visiting player was beside him waiting for the tip off, but the visiting player had his leg behind the home players leg. If the home player tried to go back he probably would have tripped over the visitors foot. The visiting player was 6'6", and his legs weren't spread overly wide with his stance. Can anyone direct me to where I can find information about proper jump positioning? This is the first time I've ever heard of this.