A Design Data Management System for CAD

In recent years there has been a tremendous increase of interest in VLSI Computer Aided Design (CAD) databases. Circuit designers often create and experiment with multiple versions of a design before selecting one that satisfies the requirements. Moreover, the complexity of designs that they be described hierarchically so that circuits at a level consist of subcircuits described at lower levels. If a circuit at a lower level changes then it affects the circuit at the higher level.