One question haunts this 79th U.S. Open and lurks at the edge of every conversation: Is this event the greatest test of golfing skill in creation, or is it the most meaningless joke in the sport?

Believe it or not, nobody - not Jack Nicklaus or the U.S. Golf Assocation - claims to know the answer with absolute certainty. In fact, they admit that the Open, as it has come to be known in the last decade, could be either.

As Nicklaus has pointed out this week, a fine line exists between a supremely difficult course that is the best imaginable test of talent, and a tricked-up layout where luck and a hot short game outweigh overall ability.

"If we continue to have sun, wind and 90-degree weather with no rain," Nicklaus said Thursday, "this course could fall into either category."

"Our margin for error has been reduced to almost nothing," Hale Irwin said before today's third round. "The difference between a perfect shot that holds the green next to the flag and a disastrous shot that bounces off into the jungle is no more than a pace or two on some holes.

"Are holes like that a test of skill or a test of luck?"

At its best, the U.S. Open demands straight drives, crisp iron shots, brilliant chipping and putting and strategic position play. Plus the patience of St. Francis and the will of Patton.

At its worst, the Open eradicates the difference in ability between a Tom Purtzer and a Tom Watson and throws both into the same jail of high rough and high-risk shots.

Which is Inverness?

Nobody knows - not yet anyway. But there are disturbing tendencies in this Open, ones which worry everyone in golf.

When Purtzer and Larry Nelson started today's round in the lead - with only two players within six shots - while Watson had missed the cut and Nicklaus was out of contention, eyebrows were raised.

Even more telling were Purtzer and Nelson's own words. Nelson says he is playing poorly. Purtzer admits he is striking the ball as badly as he has in his career.

The most damning criticism from the touring pros is that the USGA has decided that come heck or high rough, they are going to construct an Open course that will "protect the integrity of par."

"The USGA doesn't want to recognize the fact that today's players are better than ever before," Irwin said. "They seem willing to do anything to prevent us from shooting scores that would make us appear better than the great names of the past."

"Why can't the USGA leave the great courses alone and stop worrying about what we shoot?" Watson asked.

One old-timer here, the great Byron Nelson, readily admits that, "In my day we simply didn't believe that it was possible to play as well as these young fellows do.

"We thought that strength denied touch and that you could not consistently hit the ball both long and straight. It's been proved that you can."

Open scores should be lower than they were in the 1930s, '40s and '50s, if course conditions are the same. But the scores remain essentially the same.

The reason is undeniable - Open courses are made harder, and some would say trickier, each year.

When will the line between skill and luck be passed - or has it been already? Since 1969, the U.S. Open has been won by gentlemen named Orville Moody, Tony Jacklin, Lou Graham, Jerry Pate and Andy North.

Runners-up have included John Schlee, Forrest Fezler, John Mahaffey and J. C. Snead.

The hard truth is that several recent Open winners accomplished more in one week over a USGA layout than they have in the rest of their careers.

A whole sub-class of pros has appeared, who have the dignified reputation of being "Open players" since they suddenly pop into prominence in June. Graham, Mahaffey, Irwin, Ed Sneed, Dave Stockton and others are among them.

The last thing golf needs, especially in its current popularity and TV-ratings slump, is for its most prestigious event to have a tarnished reputation.

Yet no easy solution is possible. Few more chancy tasks exist than the problem of "setting up" a championship golf course with the multiple problems of growing rough, mowing greens to difficult-but-fair lengths and choosing tee and pin placements.

Each Open morning, the USGA, always at the mercy of the latest weather forecast, must decide how much to water the greens, how far back to push the tees, where to stick the flags and whether to mow off another 64th of an inch of green.

It is thankless work. Everyone in both golf and television is convinced that the public loves to see the pros humiliated, hobbling to the 72nd hole trailing double bogeys.

At this hour, with the Inverness greens - tiny to start with - getting more baked and rapid each day, no one can say if Sunday's final round will be high drama or low slapstick.

That ancient golf dictum - that "risk and reward should be in proportion to the gamble taken" - may, once again, hold gloriously true. Or every shot may become a gamble, and both risk and reward may bear little relationship to skill.

Yet, at bottom, the underlying question has been whether of not the U.S. Open should be played on old and great courses that are set up essentially as they were in the heydays of Hogan and Snead.

This Inverness Open has been lucky. Because the rough never has reached full scale hayfield standards, this course can be made playable by the simple use of hoses and good judgment.

"I was surprised. They really watered the greens this morning," said today's first starter, defending champ North, who shot 68. "But maybe they had to. Several greens might have burnt out for good by the end of the day. I think there'll be some more 68s."

Few players symbolize the problem of the U.S. Open as well as North, whose three-over-par total at Cherry Hills last year ended with a hold-on-for-dear-life bogey at the last hole.

"I've had a tough year since then. Maybe I've put too much pressure on myself," said North, who has won only one other PGA tournament in his seven years as a pro.

"But I can always look at that trophy on the mantlepiece at home and see my name up there with Nicklaus, Palmer and Hogan. It's really neat. They can't take it off or erase it, no matter how badly you play. Your name is going to be there for a hundred years."

And, of course, that is the question - one that has not been answered for 1979. Are the proper names finding their way to that old trophy, or is the grail of golf being besmirched with the monikers of gents who are wining a blind-bogey event that is almost as much a test of good fortune as good golf?