When basketball drew up collective bargaining agreements in 1984, it allowed a series of exceptions to its salary caps, and one of those was to allow free agents to earn unlimited amounts from their teams.
It was intended to make sure that, when a veteran player wanted more, and his team wanted to pay him more to keep him, then everyone would stay happy. But it has ended up as the key issue in a dispute between players and management that has already led to the cancellation of the pre-season exhibition games, and could mean the postponement - cancellation, even - of the regular season games for the first time ever.
In many respects, this is an ordinary labour dispute. The management wants, among other things, to end the Larry Bird exception, or the Qualifying Veteran Free Agent Exception as it is properly known. It says that costs in the industry are skyrocketting, and it needs to put a cap on them. The players say that this is just a way of cutting their salaries and that the industry is financially far healthier than the bosses say.
As a result, they have been locked out of their changing- rooms while management and union try to settle their differences.
But it is a dispute in a far from ordinary industry. The spoils that are to be divided are some $2bn (pounds 1.2bn), swollen by a new deal with television networks after a terrific season last year that saw Michael Jordan and the Chicago Bulls power through to yet another National Basketball Association title.
Jordan, through sponsorship and endorsement deals, is at the centre of his very own industry that is itself worth billions of dollars. Sport is booming, the television networks are proliferating and seeking new ways to gain viewers, and basketball is making money hand over fist. The issue is who gets it.
For the players, the Bird exception is an aspiration, the top tier on the cake, but also their just reward for making the game what it is.
For the owners, the Bird exception is an open-ended commitment that forces them to pour out vast amounts of cash and leaves them little leverage in negotiations, so the richest players end up taking home $20m a year. The league is offering average salaries starting at $3m and going up to $5m over the next few years. It claims that 15 teams lost money last year, though that depends on definitions, and the players say only four were losers.
The two sides will meet again today to try to resolve their differences, their first bargaining session since 6 August. But the season is due to start on 3 November and there is not much time left. Training camps were due to open on Tuesday, but their doors stayed firmly shut.
The players took the opportunity to get a little publicity, and make the case that they are not on strike: they are locked out.
"We want to show the public that we, as players, want to play," said Patrick Ewing, of the New York Knicks, who is also president of the National Basketball Association Players' Association. "Today is supposed to be the start of training camp. We want to practice, and we want the season to start. But, unfortunately, the owners have locked us out, and the season has been postponed."
Everyone is uncomfortably aware of the atmosphere generated by the 1994 baseball players' strike, an event that horrified and disgusted fans with what looked like a display of sheer selfishness. It was not until this year, with its home-run race adding joyous celebration to what had been a good season anyway, that something of the magic returned to baseball. But the owners - and players - are adamant, and do not expect a game to be played until December.
It may be that today sees a breakthrough, with the players proposing bringing in the experts to settle the dispute. According to some reports yesterday, their proposals will include playing this season under the old contract as a probationary year, and setting two economists the task of seeing who profits. It is not a bad idea in one way, because it crystallises the issue: money.
But, in another way, it will only fuel the scepticism of many fans about the game, and about sport in general.
The man whose name is at the centre of this, Larry Bird, is now a coach and part-owner of the Indiana Pacers, out of the salary race. But he sees both sides, and - crucially - that of the fans as well.
"You're telling me the league's making $2bn and they can't come up with a way to split it up?" he says. "Come on! We've never missed games and I don't want to see that happen."