I've always regarded it, and written it, as a melodic thing, that A being part of a melodic phrase going DAD (all three being eighth-notes) and choosing to throw an ornament on that first D, or not, as the case may be.
So here the top line is how I would probably write a phrase in a reel that's played like that, if I were writing a generic "any instrument" setting.
The second line shows throwing a little doubling (or whatever name one prefers) on that first D.
The bottom line shows throwing a partial cran (or double cut) on that D.
But for me all have the same underlying melody notes.
