Software maintenance programmers face the daunting task of understanding and modifying complex, unfamiliar programs that contain delocalized plans (conceptually related code that is not located contiguously in a program). Our research shows that programmers use an as-needed strategy when searching for the delocalized components which they need to understand. We have developed a maintenance tool, Whorf, that provides explicit support for visualizing and understanding delocalized plans using an as-needed strategy. Whorf supports this strategy through multiple, concurrent views of the software re with instant, easy access to additional views. It supports the understanding of delocalized plans by providing hypertext links between views to highlight interactions between physically disparate components. A study comparing the usage of Whorf and paper documentation shows that the dynamic views and structure supported by Whorf provide information more quickly and easily than the static structure of paper documentation.
