The move is meant to reaffirm the USGA and R&A view that reading greens is a crucial golf skill.
“These latest modifications provide very practical changes that make the interpretation easier to understand and apply in the field,” said Thomas Pagel, USGA senior managing director for governance.
No magnification of putting green information is allowed other than normal prescription glasses or lenses.
Hand-drawn or written information about a putting green is only allowed if contained in a book, or on paper, that meets the size limit and was written by the player or the player’s caddie.
Digital or electronic putting green maps will violate the rules if they fail to comply with the size and scale rules or if the device produces a recommended line of play based on the ball location.
“The new interpretation is a first step in the process and we will keep green-reading materials under review in 2019 to assess whether any further action is required,” Rickman said.