Supersedes
More info
- Type
- Usenet header
- Spec
- RFC 1036
The Usenet header that let one article replace an earlier one — a cancel and a fresh post in a single breath.
You couldn't edit a Usenet post; by the time you noticed the typo it had already been copied to thousands of servers. Supersedes: was the workaround: the header named the Message-ID of the old article, and every server that accepted the new one deleted the old. It suited monthly FAQ reposts and corrections, which would otherwise have left two contradictory versions in circulation.
Its weakness was the same as the cancel control message. Servers never checked that the author was the same person, so anyone forging a Supersedes could swap someone else's text for their own — a trick used liberally in the Usenet wars of the 90s. The header survives in the modern standard, RFC 5536, still with trust as its only protection.