> > I think that the concept of obsolete may also be explained in 10 > > minutes by saying that any changeset may have its own history. > > Ahhh. And that history is the graph of successors and precursors, > right? yep :D alain -- Alain Leufroy LOGILAB, Paris (France) http://www.logilab.fr Informatique scientifique & gestion de connaissances