How is 'clone' implemented?

[Timo Lehtinen]

Hello,

I just read 'selfPaper.ps' with great interest.  It left me
pondering one detail, though - which at least I couldn't figure 
out from the paper:

How is 'clone', which as I understand all objects inherit from
the root object, implemented?  Spefically, does it perform a
shallow or a deep copy of the slots in the receiver...  I would
assume a deep one of some sorts or else the clones wouldn't be 
too usable.  But what mechanism is then used to prevent clone
from recursing to 'parent' via the slot of that name?  How about 
other slots with non-primitive objects?

Thanks in advance!

Timo