Rule reference please!

[Danvrapp]

Darn it, I can't find a rule reference for this one, but I'm almost 100% sure that I'm correct.

I called an intentional foul last night on B1, and as we're lining up to shoot the two throws, a B2 creeps up to the top of the arc. Before I gave A1 the ball, I glared at B2 to let him know that I'm watching to make sure that he isn't yappin' in the shooters ear.

Of course, coach A didn't like the kid being there, but he didn't have a problem when I told him that he sure could be there, so long as he isn't disconcerting A1.

Once we got back in the locker room, my partner asked why I let B2 stand at the top of the arc. I told him because the rule is the players only have to be off the lane lines, not behind half court as commonly believed. He didnt' believe me, and I couldn't find the stinkin' rule/case play to back up my answer.

Can anyone help with a rule reference?