CHANNEL MODE j

Usage: MODE <channel> +|-j
j - Java exception
This mode allows you to have only java clients and selected legacy IRC clients enter the specified channel. For this mode to take effect you must set a key. For IRC clients to enter the channel they must supply the key, or be invited into the channel.
Privilege: channel operator
Examples:
/mode #movies +j
See also: CMODE +k

CHANNEL MODE J

Usage: MODE <channel> +|-J
J - Java exception
This mode defines an exception for CMODE +R, which only permits registered users to join. With +J set as well, Java users can join even if they don't have a registered nickname.
Privilege: channel operator
Examples:
/mode #movies +J
See also: CMODE +R