When Chambers Bay first opened, one of promotional tags for the course was the opportunity to play, "Pure Links Golf."

It made perfect sense.

The course sat on the edge of a large body of water, was made entirely of fescue grass and had just one tree on the property.

Lumping Chambers Bay into the category of a links golf course has become common leading up to the U.S. Open. Even the No. 1 player in the world, Rory McIlroy, said this week that Chambers Bay "plays more like a links course than some links courses." It was a catchy statement that was later backed up by a similar opinion from 2010 U.S. Open champion Graeme McDowell.

There's just one problem. While it's an easy label for Chambers Bay, it's technically not true.

Yes, it's got links properties, but it is a modern take on the traditional definition.

"The word 'links' has a very, very strict meaning, for those of our brethren across the pond," said Chambers Bay course designer Robert Trent Jones Jr. "For them, a links has to be near or on the sea, near an estuary, sandy landscape with fescue grasses and no trees."

While the one tree sitting on the Chambers Bay property never comes into play — towering next to the 16th tee — it's other features, while unique to golf in the United States, keep it from holding that links definition.

It can be perplexing. So before the first round tees off on Thursday, here's a breakdown of why Chambers Bay is getting that label and why it's not exactly accurate.

Why it's being called links:

GRASS: Chambers Bay was built entirely with fine fescue, on the tee boxes, the fairways and most notably, the putting surfaces. The grass is most prevalent in maritime climates and while it goes dormant for segments of the year, the grass rarely dies.

Chambers Bay is the first U.S. Open to be played with fine fescue as the primary grass on the putting surfaces, rather than the typical bent grass or poa annua. The only way to tell the difference between fairways and greens will be white dots delineating where the greens start.

"They're definitely not the prettiest greens in the world, but no fescue greens are that pretty. But it actually rolls a lot better than it looks," Ryan Moore said.

SAND: Before it was a golf course, the property was a sand and gravel quarry that eventually became a giant sandbox for course designers. There could not have been a better subsurface to construct a links-style golf course that used fine fescue grass. Many of the sandy blowout areas still contain some of the original gravel mined from the site when it was a working quarry.

LOCATION: Links courses, by nature, are generally situated where the water meets the land.

And here's why Chambers Bay doesn't meet the definition of a links course:

ELEVATION: This factor distinctly separates Chambers Bay. Links courses are built on flatter dunes with mounding in places, but no major elevation changes. Chambers Bay is full of ups-and-downs, including elevated tee shots on Nos. 5, 9 and 14, and the uphill, rising shots needed to play holes Nos. 4, 7, 12 and 13. From the top tee on the par 3 ninth, the drop from tee to green is more than 100 feet.

"There's more elevation change than any Open we've seen," USGA executive director Mike Davis said.

LAND: Chambers Bay was not simply placed upon the sandy property. The dunes and mounds which define the routing of the holes were man-made with bulldozers during construction.

THE TREE: OK, so this might be nitpicking since the one tree on the course at Chambers Bay doesn't even come into play. Among the courses for the final three majors this year — Chambers Bay, St. Andrews and Whistling Straits — Lone Fir is the only tree on the actual golf course.

But as Jones noted, the purist of links golf would not approve of that one towering tree.

"That tree has been a witness to everything that's gone on here," Jones said. "Somehow it survived the miners. It was struggling all of its life. Then it survived basically us."