One final thought that didn't occur to me before would be to make your own "provably portable" archive. The current libraries all contain a default "fall through" which handles otherwise unspecified types. This could cause surprises when moving code/archives between environments. The alternative would be to make your own archive (or perhaps a derivation) which restricted the serializable types to those that have been specifically accounted for. More work - but might be necessary to guarantee archive portability. Also this might support the idea that the archives produced be accessable by other applications which don't use the serialization library which normally would be much more awkward to implement. Just a thought. Robert Ramey