The term PI-SIGMA LINK is composed of three parts: PI, SIGMA, and RHO. PI stands for 'Process Improvement', SIGMA stands for 'Six SIGMA' and RHO stands for 'Reliability, Health, and Optimization'. PI-SIGMA LINK is a process improvement methodology that combines the principles of Six SIGMA with Reliability, Health, and Optimization to create a comprehensive system for improving business processes. It is used to identify and eliminate waste, reduce costs, and improve customer satisfaction.