In reply to Barrie Schofield II:
Adjectival Grades - these mean nothing and are in no way related to the standard at which you climb. They are only included to demoralise you. Therefore the grades at which you can fail are: Mod, Dif .....
Present day opinion uses a reciprocal adjectival system for coping with failure at a certain grade. Hence, failing on a Difficult is Extremely Severe, whilst it is only Difficult to cope with failure on an Extremely Severe. Simple, eh?
Grades are based on the climbers reach, and the system is open ended to cope with ever increasing arm length.
Is that what you were looking for?