The definition of a bunker has never been more important than it is this week at renovated Pinehurst No. 2, where native sandy areas and bunkers may look quite the same but have very different rules of play.
The decision to recreate Pinehurst No. 2 as it was originally intended – with native terrain surrounding the fairways instead of thick rough – posed some interesting rules predicaments for the officials governing this year's U.S. Open: What constitutes a bunker?
Why would that matter? Because you can't ground your club in a bunker, as Dustin Johnson learned the hard way in the final round of the 2010 PGA Championship at Whistling Straits . He grounded his club, with the assumption that he was not in a bunker, and unfortunately, that wasn't the case.
GOLF BALL MIXUP: What's the rule when you hit the wrong ball? 
So players this weekend at Pinehurst No. 2 are paying particular attention to any hazards on the course.
How will the rules committee handle this situation? Bryan Jones, co-vice chairman of the PGA Rules Committee, said it could be as simple as labeling all raked sandy areas as bunkers – and all other areas off the fairway and green as "through the green."
"First, there's no such thing as waste areas or waste bunkers under the Rules," Jones said. "In the Rules, there are three key areas relevant to the hole being played: the teeing ground, the putting green and all hazards – which include bunkers and water hazards.
"All other areas – fairways, rough, trees, bushes, shrubs, sandy expanses – are lumped into the 'through the green' category. My guess is that TV needs to hang a name on everything and thus this 'waste area/bunker' came to life."
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So unless the ball lands in an area designated as a hazard, in this case, a raked area of sand, Jones said players will be allowed to ground their club.
"If you hit it off the manicured grass at Pinehurst, you will be in the naturally existing conditions of the region," he said.
Just don't refer to it as a waste bunker.