Editing News server (section)

===Reader server===
A reader server is one that makes the articles available in the hierarchical [[hard disk|disk]] [[directory (file systems)|directory]] format originated by [[B News]] 2.10, or offers the NNTP or [[Internet Message Access Protocol|IMAP]] commands, for use by newsreaders. A reader server typically also works as a transit server, but it may operate independently or serve as an alternative interface to an [[Internet forum]].  When receiving news, this type of server must perform the additional steps of filing articles into newsgroups and assigning sequential numbers within each group.  An ''Xref'' line is usually added, listing all the groups where the message appears and the sequence numbers.  Unlike Message IDs, the numbers and ordering of articles will differ on each server; but related servers may force agreement by operating in a slave mode, re-using their siblings' Xref lines. Reader servers typically also maintain a [[NOV (computers)|News Overview]] (NOV) database that allows newsreaders to quickly obtain message summaries and present messages in threaded form.<ref name="Administering Usenet" />

Most reader servers support posting, either through NNTP or a special ''inews'' program.{{citation needed|date=August 2020}}  When an article is posted, the process is much the same as when a transit server receives news, but with additional checks. For posting, the server will normally fill in missing Path and Message-ID lines and check the syntax of headers intended for human readers, such as ''From'' and ''Subject''.  If the article is posted to a moderated group, the server will attempt to mail it to the newsgroup moderator if the Approved header is absent. Additional identity checks and filters are also typically applied at this point.<ref name="Administering Usenet" />