The ST-Viewer automation interface is designed so users can easily add STEP viewing capability to their applications.
Automation is a mechanism to manipulate an application's objects from outside the application.
To make this happen, the application exposes one or more COM interfaces. These interfaces can contain methods and properties. These become accessible to the automation client, and the exposing application becomes the automation server. Development tools or wizards can then import the type library and generate a code framework for the automation client. ST-Viewer exposes the ISTviz interface to allow an external application to control it.