NBA lays down the Twitter law

No using PDAs, cell phones or other electronic devices by players, says the NBA's Twitter rules.

The league has defined "during games" as the period of time beginning 45 minutes before the start of a game and ending "after the postgame locker room is open to the media and coaches and players have first fulfilled their obligation to be available to media attending the game."

"During games" also includes halftime, according to the memo.

Then Milwaukee Bucks player Charlie Villanueva famously tweeted during halftime of an NBA game last year.