As way of background, let me say I'm a huge fan of the ideas behind PEP, and appreciate the Paul-ness of the endeavour. In addition to clearly delineated requirements, many of the badge threads have questions about viable variations or substitutions. When a proposed alternative doesn't quite match the intention, the arbiter will often suggest perhaps starting a PE_X, hinting that everyone could have their own achievement certification systems. In the open source world of software development there is a common practice of 'forking' projects with open licenses - that is to say taking an existing project and applying modifications to it. What I'm curious about though, is if it is permissible for people to base their own PE badge systems off what Paul and the rest of the team have created.
Effectively what I'm asking is - "what license governs the PEP system?"