[Pleased of having caught Jim Fulton in verbose mode 8-]

You can store any complex Python data in the DB subject to: [...] - Subobjects of persistent objects must be "persistent" or they must be immutable, or be used immutably, as in:

So class Persistent's __setattr__ is basically also the level that transaction and undo support work on? Can I expect the undo support to work if I take care of the persistence rules, regardless of cyclic and acyclic structures? Propably about time to switch to Zope-dev... Stefan