[JoeF]

Stagger. By far the most common stagger for quadruplane (quadraplane, quadriplane, quadroplane) hang gliders is with the top wing forward. I do not have any example of a hang glider with reverse stagger where the upper wing is projectionally most rear. Other terms: Positive stagger (top wing forward) and negative stagger (top wing is rearward projectionally). When no stagger exists, then "zero stagger" or "no stagger" would seem to be the terms; maybe "neutral stagger."

Discussion open for comparing conventional stagger (forward for top wing) and the reverse-stagger option.
There are probably good reasons for stagger to be most commonly with the forward top configuration. Some biplane powered machines are with negative stagger.

[JoeF]

Not sure if Miller's model was positive or negative stagger. Anyone?

Source: Neil Larson's study clips from Ground Skimmer.