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
