>This could be done by sending special "cancel" messages; it was then up to individual Usenet servers to figure out whether to honor these cancel requests, thro

>This could be done by sending special "cancel" messages; it was then up to individual Usenet servers to figure out whether to honor these cancel requests, through unspecified criteria. The feature was somewhat hidden away in some Usenet clients to discourage pointless abuse, but it was there. In practice the cancel/supersede messages were and are never universally honored.