The chosen classes constitute the initial focus set for Dr. Jones.  The focus set is a small number of program elements at the focus of attention for the programmer and Dr. Jones at any one time.  It’s Dr. Jones job to maintain and diagram this focus set as the programmer explores designs.
	In this case the programmer wants to look at the Vehicle and Engine base classes.
	Focus+context views, showing more detail on selected classes, could help the programmer understand the program and make a good choice for this focus set.
	Also, the visualization of ``bad smells’’ in the code would be useful here.