In this schematic the "Washer,oil Bolt" is used most often.
Some items from this specific schematic: Bolt,flange,6x35, Guide,rr Brk Hose, Cup,master Cylin., M/c Sub Assy,rr.
The Rear Brake Mastercylinder (cb600fa/fa3) is made up of components including this M/c Sub Assy,rr which is the most expensive.