The keeping of all secrets within a particular event, meeting or gathering that defines:
1) all substance, discussion and efforts in such meeting, stays within the walls of the meeting "i.e" (what happens at band camp, stays at band camp.)
2) everything in this meeting, as cheltenham rules, cannot be discussed outside this meeting, lest it be a future gatherin of the same attendies.
i.e - The Freemason's conduct all of their meeting as of Cheltenham Rules. No Doubt, Dont Try, Keep Your Mouth Shut!