@lowtech
Hmm, I've never noticed anything like that in any font data I've inspected, but maybe I haven't dug deep enough. Do you remember where you've seen something like that? Kerning pairs, bearings and advance widths is how I understand kerning typically works.

But anyway, I made this because it works with any vector shape, wheter it is a font or not. I already use a version of it in my experimental font editor and text layout tools to skip the manual kerning process.