Staff is a group that is by default composed of mods, smods, developers, and sysops (And the zone "god"). Staff players can run commands that normal players cannot. They also may control bots that have connected to the server (However, some bots have their own configuration file). The names of the staff members are in a file stored in the /conf directory. By default, the file has include statements to other files in the /conf/groupdef.dir directory. You should follow the tradition, since it allows you to add commands to one file and not worry about the rest, since all the ranks higher than one category can run all the commands in that category.