TD is probably Topic/Discussion...They are like AA meetings....Here's a good overview.
Types of AA Meetings
Meetings can be categorized by their topic and format, who attends them, and the facilities in which they are held. It is also useful to consider the unofficial distinctions of small versus large meetings and smoking versus non-smoking.
Open versus closed
Mixed, men only, women only, young peoples'
Speaker, Big Book, Step Study or Discussion
Clubhouse or church
Small or large
Smoking versus non-smoking
Meetings may be "Open" (to anyone) or "Closed"(for alcoholics only). Many groups pay no attention to this distinction, and it is not uncommon for regular participants in a meeting to be uncertain whether their meeting is officially open or closed. Family and friends of the alcoholic, along with observers and students of various kinds are welcome at the open meetings. Closed meetings are reserved for those who consider themselves to be alcoholics or who are investigating that possibility for themselves. Newcomers are always welcome at closed meetings regardless of whether they have made up their minds about themselves.
Meetings may be "mixed"(male and female), men only, or women only. Meeting schedules indicate by codes(usually MO or WO) if a meeting is restricted.
AA meetings are also characterized according to their format:
Discussion meetings
Big Book Study meetings
Step Study meetings
Speaker meetings
Discussion meetings
The discussion leader introduces a topic with some brief comments and then throws the meeting open, recognizing those who indicate their desire to share by raising their hands.
Those who raise their hands and are recognized by the discussion leader normally introduce themselves by saying "My name is so-and-so and I am an alcoholic." Some people say "I am a grateful recovering alcoholic," "I am powerless over alcohol," or some other variation. Although it is generally expected, it is not required that those who wish to share identify themselves as being alcoholic.
Sharing usually begins with some reference to the topic mentioned by the discussion leader or to comments by a previous speaker, but each member who speaks is free to change the subject or to introduce an entirely new topic if they need to do so. It is expected that anyone having a particularly hard time, especially if they are thinking seriously about drinking, will bring this up regardless of whatever the original topic or subsequent comments may have been.
Certain conventions guide the content and format of sharing in meetings, although these may be and sometimes are ignored. They include:
Length around 3 minutes or less.
Personal experience, feelings, struggles valued over opinions, theory.
Avoidance of direct advice and "cross talk," i.e. telling another member what to think or how to behave.
Some relation to alcohol or to conflicts in living that can be related to the Twelve Steps.
In general a "single share" convention is followed in which no member speaks at length more than once during a given meeting, although exceptions to this are not uncommon depending upon the group and circumstances.
Identification and empathy with the experiences of others who have shared. This is expressed by sharing one's own personal experiences of a similar nature.
Occasionally the meeting "goes around the room" and everyone has the opportunity to speak if desired, or the discussion leader may call on individual members and invite them to share. Those who do not wish to speak simply say "Thanks, I'll pass" or "I'll just listen tonight." This is always accepted and pressure is never exerted to speak.
b. Meetings usually wrap up on time and are closed in a manner chosen by the particular group. A basket is usually passed around the room for voluntary contributions to defray expenses. No contribution is required, and first-timers are often advised not to contribute. The usual donation is one dollar. It is common for the chairperson to read or remind everyone of the Twelfth Tradition(the principle of anonymity) and to invite the group to stand, join hands in a circle, and recite the Lord's Prayer or the Serenity Prayer.
Big Book and Step Study Meetings
These meetings are devoted to the study of the "Big Book of Alcoholics Anonymous" or to the "Twelve Steps and Twelve Traditions"("12 and 12") written by Bill Wilson, a co-founder of AA. Participants commonly bring their own copy of the appropriate book, but there are usually extra copies available at the meeting for those who did not bring a copy.
The typical meeting will involve reading some portion of the "Big Book" or the "Twelve and Twelve" and then commenting upon it from the individual member's experience and perspective. The discussion leader may read a selected passage and then invite comments, or members may take turns reading a paragraph or two from a chosen section of the work, followed by a general discussion of the topics covered.
As in the discussion meeting, sharing that consists of personal experience and applications of the text is valued over purely theoretical and impersonal analysis.
Also as in the discussion meeting, "cross talk" is kept to a minimum. The usual etiquette is for members to remain silent until the speaker has finished.
Speaker meetings
A speaker is selected in advance who agrees to "tell their story" of drinking and recovery to the group. Speakers are usually those with a year or more of sobriety who have previously been asked and agreed to talk.
A common format is to devote the entire meeting after the usual opening readings to the speaker's story. When the story is finished the meeting is wrapped up without formal discussion.
Some meetings are combined "speaker-discussion meetings" in which a chosen speaker talks for a quarter or a half an hour, followed by a group discussion of the themes raised in accordance with the usual conventions of a discussion meeting.
Source.....
Your First AA Meeting<