To achieve today’s quality and defect-per-million (DPM) goals, high-quality testing must achieve very high defect coverage. Testing today typically consists of generating test patterns based on multiple fault models that emulate manufacturing defects. Commonly used fault models include stuck-at, bridging and transition. With each step down in process node size, there are new defects introduced into the manufacturing process. Many of these defects may be detected via the existing fault models and test pattern generation methods, but there are cases where in order to maximize coverage, a new fault model needs to be created.