Hello! Here is what I have done since 20090828 in 'hg diff' format: http://swizard.info/misc/cl-prevalence-3.patch It is going slightly uncomfortable for me to maintain patchfiles, maybe I should make a mercurial branch or something? Detailed changelog: 1. SEXP standard-object serializing: fixed a bug with no-slots objects. 2. Backup method for guarded-prevalence-system: key parameter bugfix. 3. Files external format support for prevalence-system with tests available (test/test-external-format.lisp). 4. Moved from 'copy-file'+'delete-file' to 'rename-file' in snapshot method. Have no idea why it was like that :) 5. Removed reset serialization context invocations in serialize-sexp, deserialize-sexp, serialize-xml and deserialize-xml. Context reset moved to 'snapshot' method. 6. test/test-complex-serialize.lisp: emulation of complex datasets processing under heavy load.