Had this play tonight. A has a 3rd and 4 near midfield. A is all in formation, with all A 11 players in tight formation - 2 tight ends and 2 flanker backs just outside the 2 tight ends. The same alignment that they have used for 1st and 2nd down.
A-QB looks over the alignment, goes under center and calls ready, then set. On the "set", all 7 A linemen go from standing up to "down" position, but instead of hand(s) on the ground, rest forearms on their knees. On next sound, the 6 linemen, except for the snapper, who never moves, quickly step back and stand up. Ball is not snapped but B line responds, and we have multiple pre-snap flags. Multiple B players in the neutral zone and the ball has not moved.
What do we have, and what are the keys here in deciding either False Start on A or Encroachment on B? Rule reference(s)?