<quote who="Quanah Gibson-Mount">
I think it's wrong.
"each overlay's function" seems correct to me. The function of a given
overlay, so possessive is correct. The function belongs to the particular
overlay in question. "each overlays function" seems quite incorrect to
as now you've made overlays plural and lost the ownership of function.
"Each dog's fur" for example. Not "Each dogs fur". Try googling
look at the suggestion. ;)
Yeah, my bad ;-)
The possessive form of a singular noun is an apostrophe followed by the
"the car's engine"
Please revert ;-)