Point Blank? Musings on Aiming

There is endless tedious debate and discussion on the forums about "instinctive" or "gap" shooting and such like which usually degenerates into semantics.
One problem for me is that people never seem to concisely define their terms.
I wondered how far low do I actually aim when I'm shooting at 10 yards?
I put a small piece of white paper, or as the French might say a point blanc on the lower edge of the target. I drew up, put the point on the white spot and loosed. I did it again to remove some experimental error.
You'd think it was all pretty clear now... but the problem remains how do you describe that point of aim?
In actual terms measured at the target it's about 27" below where the arrows strike. BUT imagine you are trying to explain to someone who has never shot before.
Do you say aim 27" below the target?
But what if the target is in the middle of the boss? 27" below it is now somewhere on the floor.
Or do we judge the distance below the target as measured on the bow limb.
We can do the geometry:-
27" measured at  360" (10 yards) scales down to
2.1" when measured at 28" (distance from eye to bow limb).

So am I aiming 2.1" low or 27" low ... or am I just going by feel/experience/instinct ?

The final piece of the jigsaw is that as soon as you consciously try to think about what you are thinking it changes.

Just to clarify the "point blank" thing for those who don't know the real definition:-
Point blank isn't zero range for a bow (in fact it isn't quite zero for most firearms*!) It is the range at which the white point of aim marker actually corresponds to the point where the arrow strikes (e.g the "point on" distance).
In the case above, if I was shooting at 20 yards the arrows would strike about 15" or so above the white spot. at about 35-40 yards the arrows would be hitting the white spot... (if I were a better shot) so that is the point blank range.

Comments welcomed!

*e.g A rifle with telescopic sights would hit an inch or so below the point of aim at zero range, because the sight is mounted an inch or or so above the barrel! It would presumably be zeroed in for say 20 yards?