This paper examines the role of design knowledge in the software life cycle. How is knowledge abut a program design affected by changes to the source code? How can program design knowledge be used by a diagnostic system to identify failing software components? Which attributes of design knowledge are relevant for modeling in a design repository?

This paper addresses these questions with respect to an actual system that was developed to investigate acquisition, capture, and representation of design knowledge for commercial software designs. Existing components of the system include a central repository for the program design model, a knowledge acquisition model for capturing functional and design specifications, and a rule-based diagnostic component for isolating software faults.