mastercoin-MSC/spec — pull request #41 by marv-engine (2014-01-21 18:52:57+00:00)
Title: tx=20: add Action byte for New, Update, Cancel

To simplify updating or cancelling a Sell offer, and to prevent an update from generating an unintended new Sell offer if the previous one had already been accepted.

Version # and Doc History need to be updated.