Thanks for that — the way I read what you're saying is, "If the D100 result is 20 percent or less of the Adventurer’s skill percentage but is not a result of 01-05, a special success has occurred." includes an error (and yep, I have the revised edition, so it's an error in the revised edition) and once you swap out "01-05" for "critical range" it all makes perfect sense. MW is pretty neat.