Construction history is the saved information about how an object was created. When you edit the construction history the object automatically updates.
For almost every tool, Alias gives you the option of saving the history of how an object was constructed. This means you can edit the curves, surfaces, manipulators, tool options, and so on, that were used to create an object, and the object automatically updates.
For example, when you use the Revolve tool to create an object with construction history, you can:
...and the surface(s) updates automatically.
To create construction history when working with tools, turn on the Create History option in the option window. This option is on by default in all tools.
Objects that have construction history are drawn in green in the default color scheme.