[Nevadaref]

Originally Posted by BillyMac

This is the way I explain the rule to rookie officials. Once the defender establishes a legal guarding position, the player may legally move in five of eight directions: left, back left, back, back right, and right. It is illegal for the defender to move forward right, forward, or forward left, and make contact. There may be exceptions for an airborne shooter, but this keeps it simple for rookie officials.

You missed one direction -- UP.