I'm probably opening a can of worms, but here I go anyways. This thing about not being 'Backwards compatible', I agree that it would be great but I have two questions: a) What would your suggestion be for handling new functions(features) that are in the newer file and not the older file. example: Deform or Sketch driven patterns. How should the software handle either of these features in SolidWorks version 2001? b) Do you know of any parametric solid modeler that has feature based backward compatibility?