Cool thing about inlays positioned on the headstock reverse... usually only seen by the player. They tend to be more personal in nature.
Osiris is the Egyptian god of the Underworld and "Judge of the Dead".
[shiver] 
*I notice Bill, the herringbone pattern around the outside perimeter of
"Mission Control" is the same pattern as seen around the cutout on your
#72-10 guitar! Also on
#72-001, the Jack Casady bass.