User modes available:

B	Bot (Only a status line in /WHOIS output)
d	Deaf (cannot see messages in channels)
i	Invisible (Not shown in /WHO unless on the same channel)
L	Receive an error instead of being redirected by channel mode +L
R	Only registered users can PM you
s	Server notices (see Server Notice Masks for more information on server notices)
x	Hide you IP/Host
z	Is an SSL user (cannot be +'ed or -'ed)