Probably I'm daft because it is Friday night, but AFAIK ZODB and most OODB's store an object only once, keyed by its object id. The rest is just references through that oid, so objects that belong to more than one container can be added to all these containers and n:m relations are implemented by having a list of objects on both sides.
Yes, but these references (let's call them "symlinks" ...) are not in the standard Zope. Of course it should be easy to do these things, but except for this from Shane I haven't seen anything so far: http://www.zope.org/Members/hathawsh/Symlink/index_html P.S.: Shane, have you developed Symlinks any further? I think they could be extremely useful. I tried out the initial release and liked it, except for the fact that the symlinks looked EXACTLY like real ones, so they can be very irritating ... Joachim