CHANNEL MODE r

r - Registered

This indicates that a room is registered. (informational only) (users cannot set this mode)

Privilege: Services Agent

CHANNEL MODE R

Usage: MODE <room> +|-R

R - Registered Nicknames Only

When this mode is set the server will check to make sure that a user that is joining the channel has a registered nickname.

Privilege: Channel Operator

Examples:
/mode #webchat +R