on.
&gt;
&gt; MW: Interestingly, I am also being criticised by others for not
&gt; making more of extension as being a common concept across class
&gt; and individual where whole/part and subtype/supertype can be seen
&gt; as the same.

Well, that is a pretty poor criticism.  Far from being a common concept
across class and individual, class extension and individual extension
are two completely different concepts that just happen to share the same
name.  I think this is rather obvious.  One has to do with c