Rear droop

[jaffacake]

Sorry guys for asking such a basic question but im baffled
(i have done a search,but couldnt find an answer)
Im looking at the Durango set up sheets & i understand that the rear droop is changed by adjusting the droop screws but how is the measurement taken? and where is the amount of droop mentioned on the set up sheets?
Im used to nitro rally x,where the droop measurement given is from top to bottom shock mounting points.