The PGA Tour took a big step towards banning green-reading books on Tuesday when it sent a memo to players and caddies outlining specifics of the proposed new rule. According to the memo, a copy of which was obtained by Golf Digest, the new tournament regulation, which is currently being worked on by both the R&A and USGA, will be presented to the PGA Tour advisory board on November 8 and will go into effect on January 1, 2022.

The purpose of the rule, per the memo, is to “return to a position where players and caddies use only their skill, judgement and feel along with any information gained through experience, preparation and practice to read the line of play on the putting green”.

The memo provided a four-point overview of the ban, telling players that they and their caddies may only use “Committee Approved” yardage books for tournament rounds. These books will look similar to the yardage books used on tour today with one main difference: they’ll provide only “general information on slopes and other features”. This differs from the green-reading books that have grown in popularity, which use laser renderings of greens to tell precise breaks in each section of the putting surface. To ensure that everyone uses a Committee Approved book, players will not be permitted to use any books printed for PGA Tour events before 2022.

The most interesting, and perhaps complicating, part of the memo reads as follows: “Handwritten notes that could assist with reading the line of play on the putting green will continue to be allowed in the approved book. However, such notes will be restricted to only those made by the player or caddie and must be derived from the experiences or any observations of a ball rolling on a green. This includes observations from a TV broadcast. Transferring prevoius handwritten notes that also meet the new restrictions into the approved book is allowed. No devices, levels or other technology may be used to gather information to be kept as notes, and no information may be copied from another source into the approved book.”

The memo also confirms that a player can use approved books and handwritten notes to help read a line of play on the putting green and for other strokes during the round – a noteworthy inclusion given green-reading books have long been cited as a cause of slow play on the PGA Tour.

There’s a lot to chew on there, so let’s break it down.

The first thing to know is this is a local rule that will be applied to PGA Tour events only. Green-reading books are perfectly legal in both the R&A and USGA rules. They exist for thousands of courses, other than Augusta National, that has hosted a PGA Tour event in the past, say, five years. This rule will not remove those books from circulation. So, to put this in mischievous high school terms, the cheating materials exist.

But the tour is telling players they cannot simply trace the lines on an old green-reading book into a new approved book. They also cannot look at an old green-reading book or any sort of laser rendering and make educated lines based on general observations. The message is clear here: you can only make lines if you’ve played the course or watched it on TV. A strict interpretation of that wording would also seem to ban making notes based on conversations with other players who have played the course.

What makes this potentially murky is the fact that players will still be able to mark up the illustration of the green in the approved books. (In addition to writing down break, guys will often make a huge X on parts of the green they want to avoid or draw arrows if a slope is particularly severe.) A number of players also have plenty of experience with those green-reading books; they know what a 3 percent slope feels like. So if a guy goes out there and maps out the green himself, the better job he does, the more his book will look like the banned ones. And what if a guy remembers that a particular putt he had at a past event has a 2 percent break. Is he allowed to write down that number on the approved book?

This rule, like so many in golf, will rely on the honour system. Looking through every player’s yardage book to determine if his notes disquallify a previously approved book is simply not feasible. They will also have to trust a player’s word when he says he drew lines based on experience or by watching, not by remembering the same green-reading book he’s used for a golf course for the past three years.

The memo says the PGA Tour rules staff will collaborate with the USGA to educate players ahead of the January implementation date. There will no doubt be many, many questions.