The 'VADS_Size attribute is intended to make it easier to port
legacy code which relies on the semantics of 'Size as implemented
by the VADS Ada 83 compiler. GNAT makes a best effort at duplicating the
same semantic interpretation. In particular, 'VADS_Size applied
to a predefined or other primitive type with no Size clause yields the
Object_Size (for example, Natural'Size is 32 rather than 31 on
typical machines). In addition 'VADS_Size applied to an object
gives the result that would be obtained by applying the attribute to
the corresponding type.