USER MODE b

Usage: UMODE +|-b
Usage: MODE <nick> +|-b
b - Chatops
This mode is used in order to see CHATOPS messages occurring on the server and network. Since globops should be reserved for very important oper-only messages, chatops allow opers to communicate about less important things. If an oper is very busy they might turn chatops off, but they should still have UMODE +g set.
Exactly how chatops are used will depend on the network, but they can be used simply as a way for opers to chat and have fun or for less important but still network-related oper-communications.
Privilege: operator
Examples:
/mode jimmers +b
/umode +b
See also: GLOBOPS

USER MODE B

Usage: UMODE +|-B
Usage: MODE <nick> +|-B
B - Buddy exception for +m
This mode is only effective if you have UMODE +m set, it allows all users on your buddy list to message you while you block private messages.
By using +m and +B, you can make sure only your buddies are allowed to message you.
Privilege: user
Examples:
/mode jimmers +B
/umode +B
See also: UMODE +W