User blog comment:Moooosey/Simple psi-- a fairly simple ocf/@comment-43798125-20191105221608/@comment-35470197-20191107222634

It is quite difficult to create an original OCF based on M, because of the issue on the computability and the well-definedness of another base function which "enumerates" higher inaccessible cardinals. If you do not mind them, then you can learn portion of how it works through my list of properties in this page.