Inventor 2011 includes a new feature called iLogic. It is a VBA style programming language that runs inside Inventor. It allows virtually any feature, parameter or property in an inventor file to be automatically controlled. For example, a parent assemblies can control a part or component's features such as dimensions and visibility. Using iLogic, a vessel's head type can be controlled simply by changing a string value in it's parameter table. Have a look through the tutorial to find out more.

Inventor iLogic Vessel Tutorial - Learn how to create an iLogic Vessel.