Understand Properties and Methods
ActiveX Automation Basics
Locate the Type Library
Each object has a parent object to which it is permanently linked. All objects originate from a single parent object called the Root object. You can access all the objects in the interface by following the links from the root to the child objects. Additionally, objects have a property called Application that links directly back to the Root object.
The Root object for the AutoCAD interface is the AutoCAD application.