It is not too difficult to garner a guess since for grad EO, the available subgrades are geo 2,3,4,5 seo 1,2,3 superscale h,g, f, e, d whereas for grad mx you only have mx 13,12,11,11a,10,9,8,7. So logically this must mean that there are at least multiple subgrades mapping to one mx grade at some of the levels