Stumped a bit

[jTheUmp]

Case book 5.1.2.e:
Fourth and 2 on B's 25-yard line. A1 is tackled at the 26, short of the line to gain, and B2 then piles on.

RULING: The referee shall signal a change of possession by signaling first down toward A's goal. The penalty for B2's dead-ball foul is administered and the line-to-gain equipment then set, making it first and 10 for B from its own 13-yard line.

COMMENT: On fourth-down plays, A must get a first down by virtue of the yardage gained, including any yardage or an automatic first down from penalties for player fouls during the down, or it is a new series for B automatically when the down ends unless the down is to be repeated. The penalties for all unsportsmanlike and nonplayer fouls which occur during the down in which a new series is awarded, and dead-ball fouls prior to the subsequent ready-for-play signal, will be administered before the new line to gain is established and the chain and box are set. In all cases it will be first and 10 for A unless it is inside the opponent's 10-yard line. On plays other than on fourth down, A may gain a first down by virtue of the yards gained or from penalty enforcement.