Many thanks to everyone who responded last week. I still have not grasped all the implications but have updated the Wiki (including adding the references Michael kindly provided.) to propose addressing the following issue. 1)new EPR or rewrite the old agreement => as Michael points out, accountants should not use erasers. Agreements as logs should not be erased/modified... This means concept of superceded should be added. In order to avoid racing conditions, Agreement state should be extended to allow transition from *observed* state to *is-being-superceded* followed by either *superceded* (if the agreement modification is agreed to) or *observed* state (if the agreement modification is not agreed to..) Best Regards Toshi ----- Toshiyuki Nakata 中田 登志之 Executive Chief Engineer, Central Research Lab. NEC 1753, Shimonumabe, Nakahara-Ku, Kawasaki,Kanagawa 211-8666,Japan Tel +81-44-431-7653 (NEC Internal 22-60035) Fax +81-44-431-7609 (NEC Internal 22-60509)