FUUO defines: Chatham House Rules

Not be confused with "Cider House Rules". 

I go to plethora of meetings in my current job and most of them state somewhere on the email or handout:

"Chatham House Rule apply"

or

"Please honor Chatham House Rule"

or

"Chatham House Rules are Wassup"

They usually kick off the meeting stating that all discussion and comments are 'not for attribution' which pretty much covers the definition.  BUT, in case your intellectual curiousity goes behind the 'pretty much', read on:



The Chatham House Rule reads as follows:

"When a meeting, or part thereof, is held under the Chatham House Rule, participants are free to use the information received, but neither the identity nor the affiliation of the speaker(s), nor that of any other participant, may be revealed".

http://www.chathamhouse.org.uk/about/chathamhouserule/

et en francais:
Quand une réunion, ou l'une de ses parties, se déroule sous la règle de Chatham House, les participants sont libres d'utiliser les informations collectées à cette occasion, mais ils ne doivent révéler ni l'identité, ni l'affiliation des personnes à l'origine de ces informations, de même qu'ils ne doivent pas révéler l'identité des autres participants.

Please check out their website, it has a fairly entertaining FAQ section where they answer the age-old question:

"To Tweet or Not to Tweet"