Question 1:
May a player use the toe of their putter to mark the position of their ball on the putting green?
Question 2:
May a player use a loose impediment, such as a twig or a leaf that they found lying on the green, to mark the position of their ball on the putting green?
Question 3:
May a player use a blemish on the surface of the putting green to mark the position of their ball?
__________
Answer 1:
Yes (but it is not recommended)
Answer 2:
Yes, (but it is not recommended)
Answer 3:
No, a physical mark must be used.
The Note to Rule 20-1 states;
The position of a ball to be lifted should be marked by placing a ball-marker, a small coin or other similar object immediately behind the ball.
However, the word "should" indicates that this is a recommendation of best practice and a player is not penalised if they use an object that is not similar to a ball-marker or small coin to mark the position of their ball.
Decision 20-1/16 includes these examples of methods of marking the position of a ball that are not recommended, but are permissible;
placing the toe of a club at the side of, or behind, the ball;
using a tee;
using a loose impediment
Under Rule 20-1 it is necessary to physically mark the position of the ball, so reference to a blemish on the ground does not constitute marking the position of a ball.
