When in question as to whether an action is a false start or illegal motion/shift, it is a false start.
 
When in question, a formation is legal.
 
When in question, the runner fumbled the ball and was not down.
 
When in question, the passer fumbled the ball and it was not an incomplete pass.
 
When in question on a safety related foul, it is a foul.
 
When in question on a non-safety related foul, it is not a foul.
 
When in doubt, the passer is out of the free blocking zone..
 
On a turnover or kick play, when in doubt on a threatened goal line, make it a touchback.
 
When in question, it is not a touchdown.
 
When in question, it is not a safety.