Color - Pecking Order

Black is darker than white
Black obscures white
Black is over white

Yellow is darker than white
Yellow obscures
Yellow is over white

Yellow is lighter than black
Black is darker than yellow

Black obscures yellow
Black is over yellow is over white

Green obscures yellow
Green is over yellow, is over white
Black is over green, is over yellow, is over white.

Black is an over-color relative to white.
White is an under-color relative to black

Green is an over-color relative to white
Green is an under-color relative to black

White is the lowest
Black is the highest

Which is the over-color / under-color  - pure green, pure red, pure blue