[OT] Newsgroups Support for "Cancel", "Supersede", etc.

[Roy Schestowitz <newsgroups@schestowitz.com>]

At risk of being off-topic here, I have noticed that on some newsgroups
(perhaps newsreaders or servers) do not honour some available
functionality. I got replies to superseded messages and I began to look for
explanations. I have not been successful so far. I'd be grateful to anyone
who can clarify. Is "supersede post" a deprecated notion (i.e. am I causing
clutter by using it)? Is it more of a wish-list feature that is not
globally supported?

Many Thanks in advance,

Roy