Usage: MESSAGES SEARCH <string>

Locates messages by either numeric or a text field in the message. As an Example numeric 436: %s :Nickname collision KILL. You could find that message by typing in the words "nickname" or "kill". A list of all matching items is sent to you. You can also get the exact text of a message by entering the numeric.

/as messages search nickname
/as messages search 436

Before you can set a message you need to know its numeric. The search string lets you find the numeric for any message that you want. You can also use it to find all messages with a particular word if you want to change all of those messages in a particular way. A search for "op" will find messages with "operator" or "stopped" and so forth.