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Software maintenance represents the largest cost element in the life of a software system, and the process of understanding the software system utilizes 50 percent of the time spent on software maintenance. Thus there is a need for tools to aid the program understanding task. The tool described in this paper—program UNderstanding Support environment (PUNS)—provides the needed environment. Here the program understanding task is supported with multiple views of the program and a simple strategy for moving between views and exploring a particular view in depth. PUNS consists of a repository component that loads and manages a repository of information about the program to be understood and a user interface component that presents the information in the repository, utilizing graphics to emphasize the relationships and allowing the user to move among the pieces of information quickly and easily.
L. Cleveland (Sun,) studied this question.