in my understanding, there was a type error by above member, it should be "PFY", that means, processes final yield; there are three concepts/factors related to processes performance, they are "PFY","FTY" and "RTY".
PFY=processes final yield
FTY=first time yield
RTY=rolled throughput yield
RTY=FTY1*FTY2*...&FTYn