I've developed a couple of simply Python classes which I'm using as base classes for some ZClasses that I've developed. I now realize that both of these Python classes could benefit from obtaining behavior from another class. Will I complete hose myself if I change the class definition of my Python base classes? In other words, will existing ZClass instances be completely screwed up if I do this? For example, suppose that I have a base class written in Python which looks like this: class MyFolder(OFS.Folder.Folder): ... I have a ZClass which uses MyFolder as a base, and I have one or more instances of my ZClass in my ZODB. I would like to change the definition of MyFolder to be something like this: class MyFolder(OFS.Folder.Folder, SomeOtherClass): ... Can I do this, or am I asking for trouble. Thanks. James W. Howe mailto:jwh@allencreek.com Allen Creek Software, Inc. pgpkey: http://ic.net/~jwh/pgpkey.html Ann Arbor, MI 48103