The Barracuda Championship does things a little differently than its tournament brethren, the only competition on the PGA Tour to utilise Stableford scoring. The alternate event, however, still adheres to the Rules of Golf, which is how Mark Wilson found himself disqualified on Sunday morning.

Wilson self-reported a violation of USGA Rule 4.3 (use of equipment) regarding a green-reading book. Under the latest iteration to the Rules of Golf, these materials are limited in scale for green diagrams to where a grid can be no more precise than 3/8-inch equalling 5 yards of the green. It also restricts the size of the book that contains any green information to the current pocket-sized form of most yardage books (approximately 4 1/4 inches by 7 inches). Earlier this year at the Honda Classic, Alex Cejka became the first victim of the directive, as an old green-reading book violates the new parameters. According to Wilson, a former notepad did him in as well.

“Sad to report but had to disqualify myself this morning for using a non conforming greens book during [Barracuda Championship],” wrote Wilson on Twitter. “Why I didn’t think of it before the tournament started, I have no idea…

“The confusion for me was that my 2014 greens book fit in my yardage book so I didn’t think that it wouldn’t comply with the scaling limit … I used it a few times only but once is too many. Live and learn!”

Wilson, 44, has five career wins on tour, the last coming in 2012. Though he’s made 387 starts, the Barracuda was just his third appearance this season. Wilson ended Saturday in a tie for 51st.