New York’s Metropolitan Transit Authority has reached an agreement with the Transport Workers Union Local 100, the union representing the city’s 34,000 subway and bus employees. No news there. What’s interesting is a “side letter,” also agreed, about which both the MTA and the TWU carefully kept quiet.

A side letter of this sort is a separate deal that commits to paper the wink and nod that otherwise would represent an unspoken agreement that no one is supposed to know about, but that the winker and winkee reached on the q.t.

This particular side letter has the MTA paying, over the next three years, $6 million into a union slush fund “trust established for permissible purposes.”

The payments are being made “in the interests of sound labor relations.”

Of course.