58 Pa. Code § 183.199
Not more than two horses may be drawn as also eligibles for a race and their positions shall be drawn along with the starters in the race. In the event one or more horses are excused by the judges, the also eligible horse or horses shall race and take the post position drawn by the horse it replaces, except in handicap races. In handicap races the also eligible horse shall take the place of the horse that it replaces in the event that the handicap is the same. In the event the handicap is different, the also eligible horse shall take the position on the outside of horses with similar handicap. No horse may be added to a race as an also eligible unless the horse was drawn as such at the time declarations closed. No horse may be barred from a race to which it is otherwise eligible by reason of its preference due to the fact that it has been drawn as an also eligible. A horse moved into the race from the also eligible list cannot be drawn except by permission of the judges, but the owner or trainer of such a horse shall be notified that the horse is to race and it shall be posted at the office of the Race Secretary. All horses on the also eligible list not moved in to race shall be released at the designated scratch time prescribed by the Presiding Judge of the meet. Also eligibles shall be considered as if they were drawn to race.
58 Pa. Code § 183.199
This section cited in 58 Pa. Code § 183.60 (relating to presiding judge).