The State Department and dissent

Today I saw the UN secretary general Ban Ki-Moon speak at Princeton.  I became curious about how people generally enter foreign service jobs and poked around a bit on the State department's web page.  I found this FAQ, which had an interesting (but reasonable) tidbit about dissent in such positions:

25. Does the system tolerate dissent?

As public servants, Foreign Service Officers must publicly defend U.S. government policy, despite personal reservations. There is an internal channel through which an employee may present dissenting views on specific foreign policy issues. If an officer cannot publicly defend official U.S. policy, he or she has the option to resign.

I'm curious about what this internal channel for presenting dissenting views is.

Update: this public state department dissent guide details this channel.  

Steven Rosefielde describes this pathway cynically in Russia in the 21st Century:

Dissent Channel, a product of the Vietnam War era, is an established vehicle for the submission of dissenting views on important policy issues.  Messages in this channel are not subject to clearance procedures and are distributed to the top policy officials of the State Department, but not to other parts of the government.  Dissent Channel rarely changes policy, but is a venting mechanism (and a way of identifying troublemakers).  It has been used more often than one might think...

Are these messages available to Freedom of Information Act requests?  Rosefielde's attempt failed; he received this message in response to a FIA request for one of his own dissents in this channel:

release and public circulation of Dissent Channel messages, even as in your case to the drafter of the message, would inhibit the willingness of Department personnel to avail themselves of the Dissent Channel to express their views freely