Well, that was its original working title. Chip, Bill, and I have greatly improved this paper, now "Capability-based Financial Instruments", and submitted it to FC'00 (Financial Cryptography 2000). I believe it is the best statement to date of the rationale for E, and more. It's available at
http://www.erights.org/elib/capability/ode/
Enjoy!
Cheers,
--MarkM