USER MODE r

Usage: This mode is automatically set on a user if they have the priviliges configured in their operator configuration.
r - Registered
User is using a registered nickname and has identified for the nick. This is only meant to be informative, users cannot set themselves + or - r.

USER MODE R

Usage: UMODE +|-R
Usage: MODE <nick> +|-R
R - Registered users exception for +m
This mode is only effective if you have UMODE +m set, it allows all users with registered nickname to bypass the message block.
This is useful if you only want to block unregistered users, which also greatly reduces the possibility of receiving spam or being flooded.
Privilege: user
Examples:
/mode jimmers +R
/umode +R
See also: UMODE +M