This is $Revision: 1.11 $.
Versions not described here are minor editorial and typo-fix updates.
20 May 1999, version 1.1 -- draft.
18 Jun 1999, version 1.2 -- first private review version.
24 Jun 1999, version 1.5 -- first public release.
24 Jun 1999, version 1.6 -- minor update; point at definition of `hacker'.
24 Jun 1999, version 1.7 -- minor update; clarify criterion (e).
24 Jun 1999, version 1.9 -- `future-proofing', the `Free the Future' model, and a new section on exclusion payoffs.
24 Jun 1999, version 1.10 -- Better name for the `Razor Blades' model.