Guido> Yeah, but the runtime could offer a choice of data types -- for Guido> Python code the constants table would contain Python ints and Guido> strings etc., for Perl code it would contain Perl string-number Guido> objects. Maybe. So I could give a code object generated by the Python compiler to the Perl runtime and get different results than if it was executed by the Python environment? Perhaps it's time for Eric to chime in again and tell us what he really has in mind. I can't see the utility in having the same set of opcodes for the two languages if the semantics of running them under either environment aren't going to be the same. It seems like it would artificially constrain people working on the internals of both languages. Skip