Slide 6
Frequently, programs are organized into high-level conceptually-distinct sections. Unfortunately, there are often many links between the individual parts of these sections, which must be understood by the programmer. They make it difficult to study any piece of the program in isolation. How can a program be shown at a level of detail halfway between code and diagram? How can we decide which parts of the program can be ignored at any given time? How can we allow programmers to indicate which parts of a program they're interested in?