IRQL and CPU rings?

How do these two fit together?

Look at this cool picture showing the IRQL priorities: http://www.winntmag.com/Files/298/Table_01.html


NOTE: There is a reserved level (31), it's even higher than power event!

If you thought ring-0 means (high priority), does it still seem so high when you look at the bigger picture? I don't know.

So, what I want to know is: Is the hierarchy of CPU rings just a part of a much larger hierarchy (IRQL)?