what none of what you said is particularly relevant to the point raised here.

I think I'm just not very happy to call these "value types" as I did when I rewrote the whole type section of the manual. Maybe "singleton" type is better, null fits better into that as the null type consist only of the singleton type null.
But still not sure about this whole topic.

"Value type" might be confusing (see https://en.wikipedia.org/wiki/Value_type_and_reference_type). "Singleton type" might indeed be a better alternative.