I line in an
IRC Server's configuration which describes nicknames which are "
quarantined" - that is to say, they are not allowed to be used, for example, SlashNET has Q:Lined *Serv* to stop people pretending to be
IRC Services.
Format:
Q:*:comment:mask
In cyclone at least, there's also (in no particular order) a K:Line, O:Line, C:Line, N:Line, X:Line, A:Line, M:Line, Y:Line, I:Line, U:Line, L:Line, H:Line and a P:Line. There's also a G:Line