It says "values of type B", as in "instance of type B", can be passed as if they are "instance of type A" (which they are actually). But yes, values inside B s

It says "values of type B", as in "instance of type B", can be passed as if they are "instance of type A" (which they are actually). But yes, values inside B specific to type B will not be able to be accessed when manipulating the type A.