(however, new forwards can still be set subject to +F).
+C - Disable CTCP. All CTCP messages to the channel, except ACTION,
are disallowed.
+
+FROM EXTENSIONS:
+ +O - IRC Operator only channel.
+ +A - IRC server administrator only channel.
+ +T - No NOTICEs allowed in the channel.
+S - Only users connected via SSL/TLS may join the channel while this
mode is set. Users already in the channel are not affected.
-
+
WITH PARAMETERS:
+f - Forward. Forwards users who cannot join because of +i,
+j, +l or +r.