What does the "room to land" rule actually say?

[Realist2]

I apologize if this has already been addressed. I've heard that "a player has to have room to land" when players shoot threes. I've seen it called in all different ways. I've seen players kick out their feet, drift forward, jump into the defender, etc. I witnessed a high school game last night in which a player's feet drifted forward and he landed on the defender's foot. It wasn't called but the fans are up in arms. The defender made no contact with his upper body and if the shooter had jumped vertically there would have been no contact. I'm just curious as to what the rule really is.

Thanks.

[Lighthouse]

I couldn't find a reference to "Room to land." This should help.

Rule 4; Definitions.
Section 39. Verticality
Art. 1. Verticality applies to a legal position and also to both the offensive and defensive players. The basic components of the principle of verticality are: a. Legal guarding position must be established initially, and movement thereafter must be legal. b. As long as no other player is occupying a space on the playing court, any player may legally occupy that space. c. The space that a player may legally occupy is defined by an imaginary cylinder surrounding the player, which extends from the floor to as far above the player as he can jump or extend his arms and body. The diameter of the cylinder shall not extend beyond the hands/arms on the front (the arms bent at the elbow), the buttocks on the back and the legs on the sides. These dimensions may vary according to the height and size of the player. d. The hands and arms may be raised or extended to the front no further than the feet and knees when the arms are bent at the elbow. e. From such position, the defender may rise or jump vertically and occupy the space within his vertical plane. f. The hands and arms of the defender may be raised within his vertical plane while the defender is on the playing court or in the air. g. The defender shall not be penalized for leaving the playing court vertically or having his hands and arms extended within the vertical plane. h. The offensive player, whether on the playing court or airborne, shall not “clear out” or cause contact that is not incidental. i. The defender may not “belly up” or use the lower part of the body or arms to cause contact outside his vertical plane or inside the opponent’s vertical plane. j. The player with the ball shall be given no more protection or consideration than the defender in the judging of which player, if either, has violated the principle of verticality. k. The offensive player must be allowed enough space to make a normal basketball play. The defense may not invade the vertical space of the offense and make illegal contact when the offensive player is attempting a normal basketball play. A normal basketball play in this context includes shooting, passing, dribbling or pivoting.