The line-count and references fields may be empty. If the optional other headers are present, they include their header keyword and colon; if they are absent entirely, the tab after the line-count field may also be absent.
The file is maintained in numerical order, by article number.
At the time of writing (late 1992), the lines in an overview file are typically 150-300 characters long, and an overview file for a typically busy group is often 30,000 bytes to 60,000 bytes long, with notable exceptions exceeding 500,000 bytes.
8870|strange message id's: <something>QUIT|schmitz@scd.hp.com (John Schmitz)\ |18 Sep 1992 19:57:16 GMT|<19dcasINNce@hpscdf.scd.hp.com>||821| 8871|Re: BNF rule for newsgroup names?|kris@tpki.toppoint.de (Kristian Koehntopp)\ |Fri, 18 Sep 1992 17:51:09 GMT|<1992Sep18.175109.21999@tpki.toppoint.de>\ |<43GQBM4D@cc.swarthmore.edu> <BuLB9y.7Dp@world.std.com>\ <BuLG5A.xH@cs.psu.edu> <339@blars.UUCP>|926||Supersedes: <1234@foovax>
There is some confusion about whether the order and content of the first eight fields is a local decision, or a standard. It's intended to be a standard; please do not mess with it. All, repeat all, local variations should be done by adding the optional fields at the end, and those fields must include their header keywords (and colons) to make them self-identifying.