Figure 2. Access Secondary Interfaces Visual Basic programs don't see the actual ActiveX control you create; instead, they work with an intermediate Extender object, which VB builds the first time the control is loaded in the IDE. This object's definition is stored in an OCA file in the SYSTEM directory. The Extender object employs the same interface as the original control, as well as some properties, methods, and events VB adds. One Extender property, Object, returns a reference to the actual ActiveX control. You need this reference to access any secondary interfaces exposed by the ActiveX control.