f()
{
	local str=F
	g str
}

g()
{
	local -n ref=$1
	printf "%s " "$ref"
	ref=G
}

str=OUTSIDE;
f

printf "%s\n" "$str"

unset -f f g
unset str

f() { local -a arr=(F); g arr; };

g() { local -n ref=$1; printf "%s " "${ref[0]}"; ref=(G); };

arr=(OUTSIDE);
f;
printf "%s\n" "${arr[0]}"