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CF = compound bow shot using fingers.

RF = recurve bow shot using fingers.

CR = compound bow shot using release.

 

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I've always taken Easton's wording to mean the bottom edge of
your typical brass nock set is to be 1/2" above 90 degrees (starting point
for RF and CF) and 1/4" above 90 degrees (starting point for CR).

 

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I took the liberty of drawing some nock heights whilst the morning's cuppa started to work -
I pray the caffeine timing proves correct

It's interesting how Easton's 1/4" CR recommendation moves arrow shaft somewhere into it's median.

Given all this, I'm thankful we have nock height tuning methods...

 

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If you also had a second nockset below, would the zero line on the bow square be on the top edge or bottom edge of that second nockset?

Arcus, it might, and it might not. It would depend on the width of the arrow nock itself and
the diameter of your chosen arrow shaft. Taking a big picture view, Easton's nock-set suggestions
are only that. One can then tune nock height by comparing vertical impacts of fletched arrows
and bare shafts at say 20 metres or so. In my experience, very small vertical changes in the
nock-set height are the way to go, a 16th of an inch at a time. Hope that helps.

BTW, you might want to investigate tied-on nocks. They're handy, as one can screw them up
and down the serving like a nut on a bolt. Mind you, that's TWO of the buggers; one above,
one below the arrow nock.

 

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I'm seeing 7/16" in top photo, 1/2" in bottom photo.