What Not to Say
To begin with, there are certain things that are inappropriate to discuss. These things include: * your own or someone else's involvement with an underground group
* someone else's desire to get involved with such a group
* asking others if they are a member of an underground group
* your own or someone else's participation in any action that was illegal
* someone else's advocacy for such actions
* your plans or someone else's plans for a future action
Essentially, it is a bad idea to speak about an individual's involvement (past, present or future) with illegal activities, or with activities that may raise the interest of the state (such as advocacy of certain groups or tactics). These are unacceptable topics of discussion regardless of whether they are rumor, speculation or personal knowledge.
Please note: this is not to say that it is incorrect to speak about direct action in general terms - just be sure that you don't link individual activists to specific actions or groups. It is perfectly legal, secure and desirable that people speak out in support of all forms of resistance.