Yah I read up on the Irish Army Rangers and their qualifications seem the same as all the other Special Forces only they, along with the SAS, seem to have very rigid requirements just to be able to recieve training...let alone actually making it through training.
They study and practice several different areas of training and then specialize in 4 additional areas of expertice out of a list of offered fields. Sort of like electives for college students.
no where did I see any sort of numbered ranking system.