Q3.6 Can moderation be accomplished retro-actively?

    To most people, newsgroup moderation means the process of
    filtering and approval-before-posting described above.

    Cancellation of messages by a third party - someone other than the
    poster or the poster's system administrator - after the message
    has been posted is sometimes referred to as retroactive moderation.

    Some on-line services and Fidonet use cancellations issued by
    service employees or by Fido sysops as a way of keeping discussion
    in their conference areas by their subscribers on-topic.

    While cancellation and moderation may seem superficially similar,
    there are strong sentiments in Usenet against third party cancellation.

    The net news protocols allow the sending of control messages,
    messages which contain instructions for news servers, usually to
    cancel or supersede other messages.  This allows people to cancel
    messages sent by mistake, or sent in error to the wrong newsgroups,
    or to cancel a "for sale" ad after the item has been sold.

    The effect of cancel messages depends on how each individual news
    server site is configured - a site may honor or ignore a control
    message, or send a message on to a human for manual handling.

    Cancellation of messages is a touchy subject, because cancellation
    can be abused, and because it can be difficult to distinguish why a
    message was cancelled - was it because a message was posted to many
    groups, or because of who posted it, or because of the content of
    the message?

    It is generally accepted that people may cancel their own messages,
    and that ISPs or system administrators may cancel messages which
    originated at their site and which are inappropriate for some reason.

    It is generally accepted that a moderator may cancel messages
    posted with forged approval to a newsgroup s/he moderates.

    It is less accepted that a moderator may also cancel messages
    that the moderator (or a mod-bot) initially approved and posted,
    if the moderator later finds the message inappropriate for some reason.

    Since 1995, a number of people routinely issue cancel messages
    for messages excessively cross-posted or multiply posted to large
    numbers of newsgroups.  (Such posts often are called "spam".)

    Cancellation based on the number of newsgroups an article is
    cross-posted or multi-posted to, or of binary posts in non-binary
    newsgroups, or of commercial advertisements in non-commercial newsgroups
    are often widely accepted as beneficial to the affected newsgroups.

    However, there is less agreement about cancellation based on content
    - such as whether a message is on-topic or off-topic for a newsgroup,
    a decision which is usually much more of an opinion or judgement.

    A key issue here is whether cancels are supported by the wide
    majority of the users of a newsgroup, and are issued by people who
    have the support of such a majority.  If there is a sense of wide
    community support, retroactive cancellation could be effective in
    fostering on-topic communication in an UNmoderated group.

    However, use of retroactive content based cancels without wide
    support can often lead to meta-discussions about the cancels,
    which be worse for the signal/noise ratio than the cancelled posts.

    So, while newsgroup moderation and retroactive cancellation both
    rely on people making decisions about the content of newsgroups, the
    key elements that they should share are wide support, prior consent,
    an expectation of predictability, and a degree of accountability,
    and the key differences are that moderated groups are formally set
    up with a central moderation address, while groups that rely on
    retroactive cancellation are usually otherwise unmoderated.

    For more about cancellation of articles, see:
        http://www.math.uiuc.edu/~tskirvin/home/cancel.html The Cancel FAQ

    If you are thinking of cancelling other people's news articles,
    *for any reason*, you should check your internet provider's policies
    or "terms of service" first, or contact their support staff to see
    if they allow this activity, and to make them aware of your plans.

    Section 4 - What does it take to become a moderator?