The programmer can add an instance of the CAnnoData class to the CDocument class. There are functions for handling the user interface events, updating the user interface elements, and accessing the annotation engine without using “C” Api. function calls. Most of its functions are called from the CDocument class, and there are some functions invoked from the CView class. Modifying the existing sample source code the user can customize the user interface, and can build a whole MFC application.