" C: Searching based on channel creation time, via the "C<val" and "C>val"
modifiers to search for a channel creation time that is higher or lower
than val."
-- <https://modern.ircdocs.horse/#elist-parameter>
-- https://datatracker.ietf.org/doc/html/draft-hardy-irc-isupport-00#section-4.8
Unfortunately, this is ambiguous, because "val" is a time delta (in minutes),
not a timestamp.
On InspIRCd and Charybdis/Solanum, "C<val" is interpreted as "the channel was
created less than <val> minutes ago
On UnrealIRCd, Plexus, and Hybrid, it is interpreted as "the channel's creation
time is a timestamp lower than <val> minutes ago" (ie. the exact opposite)
"C: Searching based on channel creation time, via the "C<val" and "C>val"
modifiers to search for a channel that was created either less than val
minutes ago, or more than val minutes ago, respectively"
-- https://github.com/ircdocs/modern-irc/pull/171