Cannot find NFHS rule

[Hawks Coach]

The exception for fan BBs goes both ways, that is, it applies to balls that go over the front to the back and over the back to the front. The fact that the fan BB is smaller could explain why they don't penalize a shot that goes over front-to-back, because it is much more likely to occur than with a rectangular BB. However, since on a rectangular backboard it is harder to go over the top, that same logic could be used to say you should never go back-to-front on a fan backboard because it would normally be hitting the back side of a rectangular BB.