The NBA Collective Bargaining Agreement expired at midnight Friday morning, and, for the second time, a major professional sport has a work stoppage.

But this one could last a while.

The owners and players are far apart on just about every facet of the negotiations.

Many believe that the 2011-12 NBA season is in jeopardy because of the chasm between the two sides.

The NBA has been pretty succinct about what is and what is not allowed during the lockout:

Coaches, general managers and other front-office officials are allowed to follow players on Twitter, for example, but they can't send them a message or re-tweet a player's message, a source told ESPN's Ric Bucher.