The NBA informed the Boston Celtics and Los Angeles Clippers days ago that their trade centering on Doc Rivers being sent to the Clippers with Kevin Garnett -- even if broken into two separate transactions -- is not permitted under league rules, according to sources.

There is no separating the two moves at this point because it is clear all pieces are meant to be part of the same deal.

"The teams are aware that the collective bargaining agreement doesn't authorize trades involving coaches' contracts," Stern said Thursday on a radio show.

The only incentives other than player contracts that are permitted in NBA trades, Stern said, are draft picks and cash.

"The teams know that," Stern said. "It has been confirmed to them. ... It can't be gotten around by breaking it up into two transactions."