CORBA24 — value type substitutability

Chapter 5.2.5: Value type semantics should not define that an instance of a
value type can be passed (directly) as a parameter that is declared as an
interface type. The reason is that this is not true in some of the language
mappings (e.g. C++) because it contradicts the kind and nature of value types.

A value type instance IS NOT an object reference even if it is registered with
the ORB. Therefore, if a construct conceptually is not a subtype of another
construct, it should not be possible that it substitutes the other. Also, it
should not be required that there are any shortcuts which automatically convert
a registered valuetype to it's associated object reference.

Clarify the ambiguity that leads to the possible inappropriate interpretation