set status_mode [<text>]
This variable sets the string displayed in the status bar when the current channel has at least one mode set (not including +o or +v). If no modes are set, nothing is displayed.
This string is represented as %+ in the STATUS_FORMAT string. When used inside STATUS_MODE, it will expand to the actual modes and their arguments.
Customizing the appearance of the channel modes in the status bar:
/set status_mode Mode %+