They provide a means of posting announcements to a wider UK audience than the readership of the newsgroups in which their subjects would naturally place them.
Announcements targetting a global audience are inapproriate.
Any post that is not announcing something is unacceptable. Hereinafter any reference to uk.announce includes uk.announce.events where appropriate. The moderator may redirect submissions from one group to the other. Follow-ups within the group are only acceptable when from the original poster repairing a factual error. Announcements must not depend heavily on specialist knowledge or external sources of information in order for it to be clearly understood what is being announced.