what is operator group for?

[Chris Whitehouse]

Hi all

can anyone tell me what the operator group is for, or docs where I can
read about it? I see that /sbin/shutdown and /sbin/mk_snap_ffs are both 
executable by members and various things in /dev/ are mountable by them.

I want a regular user to be able to mount removeable media and shutdown 
the computer. If I make them a member of operator group what else am I
allowing them to do?

Thanks

Chris