p - CTCP: This will prohibit others from sending you ctcp commands.
e - DCC: When this mode is set dcc transfers cannot be sent to your client
m - Moderated: This will protect you from getting direct messages from other users.
i - Invisible: Makes a user invisible, you will not be able to see what channels this user has joined unless you are in a channel with that user.
s - Server messages: Allows you to see messages that the server sends.
n - NewsFlash: This will allow the users to receive newsflash messages.
w - Wallops: Messages sent by ircops to users will be visible.
j - Java user mode only.
c - Clients: (Operators Only) See clients entering and exiting the server.
g - Globops: (Operators Only), GNOTICE messages
a - Services Administrator (Operators Only) set Server Administrator status.
h - Helpops (Operators Only)
x - IP masking of the hostmask which helps to prevent denial of service attacks. In the formation of =numbersletters or numbersletter=
r - User is using a registered Nickname that matches the mask.
R - User has identified to NickServ with nickname password.
t - Reports (Operators Only) This mode will show you a report of what is done on the server, such as, /stats commands, /admins everytime someone issues those commands you will be notified.
k - KillMode (Operators Only) Will show you all the kill messages occuring on your server and the network.
y - Whois (Operators Only)
b - ChatOps (Operators Only)
f - Flood Notices (Operators Only) Will notify you in server notices of floods
o - Operator (Operators Only)
z - Services Agent/bot mode Only. Prevents the server agent/bot from being kicked.
A - Server Administrator (Operators Only)
L - Language filtering mode. If filtering is set on the server the user with this mode will have selected language filtered with ***. This mode says the user has sensative ears.
X - (Operators Only) Mostly used by Scripters, in commands such as /userhost . The +X mode will break the +x mode except on channel information +x for ircops remains and will not be broken by the +X mode.