Dragan,

>In this example you have only one property, which is different in any subclass of the initial class. The whole chain is loaded, and all the definitions are here. What I'm supposing, is that if there was some Prop2, which was redefined only at B and D level, and overrriden in the object itself, wouldn't use any space in C level, and if it wasn't redefined in object x, wouldn't have space allocated in that object either. Is there a way to measure this?

If any of those levels had not overridden the property you'd see it's value as that of it's ParentClass. I'm not sure you can accurately detect the property space consumed by the class definition, we don't really have good measurement tools, other than sys(1016) which isn't too accurate.