CommonLoops was proposed by Xerox to be the OOP system of Common Lisp in the standardization process. It was then decided to design a new system called Common Lisp Object System (CLOS), starting with a merge of the features of New Flavors (MIT/Symbolics) and CommonLoops (Xerox). Xerox implemented CLOS by modifying its CommonLoops implementation, during the standardization process. Thus Portable CommonLoops (PCL) was eventually the prototype CLOS + MOP implementation.