Comment 4 for bug 588132

I trust Inkscape and also think it follows SVG1.1 specification (that, I have to admit, I don't master at all).

But I don't think SVG1.1 spec would specify where to put the "precise location" in the marker.

Furthermore, if you compare Triangle markers with Diamond markers, you could see that those empty and full Diamond markers are more "symmetric": a proof that both of them are supposed to be counterpart of the others.