Explicit History in Rhino

The "Explicit History" plugin for Rhino 4.0 is currently in development. It provides an interface to make the history of modeling steps explicit (visible) instead of being hidden behind the scenes.

It allows users to define a parametric history tree for modeling, not unlike Bentley Generative Components. Beware that it is still in development and that many steps in the Rhino modeling flow are not exposed with history at all.

http://en.wiki.mcneel.com/default.aspx/McNeel/ExplicitHistoryPluginMainPage.html

System requirements: Rhino 4.0 SP3

A nice example of the possibilities of this plugin can be followed at the DesignReform blog.