Nested XWikiObject classes?

[THOMAS, BRIAN M (SBCSI)]

I've read about the possibility of creating arbitrary types in
XWikiObject fields, though I haven't found how to do that.  One way of
doing it would, of course, be to allow another XWiki class as a type.

I'm not certain of the advisability of such an approach, but putting
that aside, would it require changing the XWiki server code to allow
such a thing to happen?

brain[sic]