This command and the previous few lines check whether it is possible to frag the enemy even though it has moved out of the line of fire. If there was a barrier directly behind the square where the enemy was, then the enemy can be fragged by launching a missile into the barrier.

The two cmath commands calculate the coordinates of the square directly behind where the enemy was. This square is then gps-scanned. If it contains something which a missile can crash into (i.e. not a space or a friend - that wouldn't be very nice would it!) and if torque has enough ammo and fuel to launch a missile, and if Torque is not in danger of being hit by a missile himself, then he jumps to a routine to launch a missile and frag the enemy.