No doubt, virtually all of us who are beyond the beginners stage have played a Four-Ball competition of some sort.  Often referred to as "Best Ball," this pits two players against two other players in a match or stroke play.  But, this format by its unique nature, can have some unique circumstances arise.  How do the Rules deal with these?  In many cases, Rules 1-20 are sufficient, but not always.  Thus, Rule 23 tells us what to do in those situations in which Rules 1-20 do not give us an answer.  Enjoy ... and don't be surprised to find that you learned more than you anticipated.