Server Broadcasts covers operator wallops and administrator announcements sent from the Admin Console Broadcast tab or slash commands.
Broadcast Tab
In Admin Console > Broadcast, choose Wallops or Announce, enter a message, and send it through the same command handlers as /wallops and /announce.
Wallops
Wallops messages go only to users who enabled +w with /umode +w. Server operators and administrators can send them.
Announcements
Announcements go to every connected user and bypass ignore filters. Only server administrators can send them.