In addition to the numerous named hooks provided by the client (refer to the ON command in Section 5), EPIC can hook any numeric reply sent by a server. They are treated no differently from named hooks. Space constraints prevent a full discussion of all server numerics, not to mention that they tend to differ from network to network.
A small subset of commonly used numerics are provided for convenience. A mostly full listing can be found in the irc protocol specification, RFC 1459 (though you should look in the ircd source code for an exact list; they are in the file s_err.c in standard ircd distributions).
Replies to /whois: 311-313, 317-319 Replies to /mode +b: 367, 368 Replies to /trace: 200-206, 208, 209, 261, 262 Replies to /stats: 211-219, 241-244
Common error numerics: 401 (nickname doesn't exist) : 404 (can't send message to channel) : 421 (unknown command) : 436 (nickname collision server kill) : 465 (you're banned from server) : 473 (can't join channel, invite-only) : 474 (can't join channel, banned) : 482 (you're not a channel operator)