American Football Rules IFAF Approved Ruling 6-5-3:I

I. A1 or B1 signals for a fair catch beyond the neutral zone during a kick that does not cross the neutral zone. RULING: Any signal by Team A is ignored. Team B may not make a fair catch signal because the ball did not cross the neutral zone. However, the ball is dead when caught or recovered (Rules 2-8-1-a and 4-1-3-g). [Cited by 6-5-3-c]