This form of competitions divides up which holes will be scoring ones for the competitors according to the alphabet
A T and F competition divides, for scoring purposes, the holes according to their initial letter. Those nine holes which start with a T or an F – 2, 3, 4, 5, 10, 12, 13, 14 and 15 – are scored differently from the other nine.
There are two ways in which the game can be played. The simple version is that an individual or team scores only on those holes which start with T or an F. The other holes are still played in the round, but they have no influence on the total score.
There are obvious disadvantages with such a method of playing. Prime among them is that it is not clear what is the point of playing the non-scoring holes - except for practice and to get in the groove maybe.
Most especially, what is the point of playing the final three holes as you can’t even claim they are practice for what is to come, and what is to come is merely more practice...
So the more popular version of a T and F competition is when it is played by teams of two. In this version the team score is made up of one of the players’ score for the T and F holes, and the other players’ score on the remaining nine holes.
The teams can either decide in advance themselves who gets to score on the T and F holes and who on the other, or it can be selected in advance by the competition organisers.
A third way is that it is decided randomly by the competition’s organisers but only after the players have completed their round.
The obvious benefit of the third way of determining who is who is that both players are in the game for all 18 holes as at that stage they do not know whose score on the hole is the one which will count.