"Avery Fay" <btmore@gmail.com> wrote in message news:8c0e97d80706272358t40351f2ds1d5e9e4192d15d1d@mail.gmail.com... Thanks for your replies. It turns out that you don't need to export the base class. I've done some experimenting and this is what I've come up with. Hopefully, this will help someone else. 1.) You can export from a header file, but if you do you can't include that header more than one time in your program or you get multiple definition errors. This goes for one export per header as well as all exports in one header. *** I would amend that to say that in order for export to work as advertised, a header containing it should be included in one and only one module which also contains archive headers. 2.) Exporting from a source file doesn't work as I posted before. You *have* to include the iarchive and oarchive headers in your cpp file you're exporting even if they aren't needed there. Missing one or the other or both leads to exceptions or plain old crashes. Unless I'm missing something, the whole export system seems incredibly fragile. *** it IS fragile. The latest version by D. Abrahams is much inproved and will be part of bost 1.35. Robert Ramey