$ulevel
Returns the user level that was matched for the currently triggered event.
The matching level when you trigger an event is your own level.
Also:
When you join a channel, mIRC knows of only one user on that channel, you. You have to wait until the names list is sent (raw 366 is the end of /names list) to know of other users on that channel, and you can't tell their user level until you have them in your IAL.
