Run-time requirement tracing

This work extends previous work on run-time tracing of the design activity in order to handle dependencies between design data in a uniform way, including requirements and deliverables. Each requirement is stored in a card; several cards are organized into linear hierarchical stacks. The system offers: requirement tracing, impact analysis, support for requirement analysis, automatic retracing. The contributions are: (1) the run-time property, which assures a detailed representation of dependencies, (2) the linear organization of the stacks of cards, and (3) the uniformity with which all design data, from requirements to deliverables, are treated. A prototype has been used in a real design.