If, after establishing by common consent the right of replay of a drive at a specified point or points during a round, a group of players additionally agree among themselves to allow a right of preference as to play of the first or second ball, a player who has hit a revisional ball (mulligan) following an unsatisfactory tee shot shall have the option of playing either ball, subject to the following restrictions:

1. Before leaving the teeing ground, he must designate which of the two balls he will keep in play, and he may not later amend or alter his decision if it thereafter proves to have been imprudent.
2. If he chooses to keep his original ball in play and pick up his second ball, he shall nevertheless be deemed to have hit his one permitted revisional ball (mulligan), and he may not hit another such ball on a subsequent tee even if he would have been otherwise allowed to do so under prevailing conditions of permissible replay.

However, a player shall not be deemed to have exercised his right to replay a tee shot if his revisional ball (mulligan) was so absurdly mis-hit as to constitute a frivolous ball (see: Exception 3).