This creates a more strict version of the +i user mode. When this is enabled (it is by default) the server will not allow users to message other users that are also +i that do not meet the following criteria:
1) They don't share the same channel.
2) They don't have a watch for the other user. (Both sides must have watches set).
3) The user is not a buddy.
/as security set superinvis off
This prevents mass messaging outside of the channel environment and allows users to only communicate with those that already have an aquaitence with.