[Zope] copying and pasting Zclass instances?

Can someone point me towards docs that describe how to add copy/paste ability to my ZClass? At the moment Zope (2.1.6) throws an exception when I attempt to paste with the message "The object <id> does not support this operation". I have a nagging feeling that Zope doesn't have this ability, though I'd love to be proved wrong. Cheers, Darran.