A great question, thanks for asking it... and that post by Dr Friday is possibly the most authoritative answer you could have dreamed of. Frustratingly vague and perhaps not the pot of golden clarity that you were hoping for, but given Dr Friday's background, I suspect it is as close to a definition as you are likely to find. There may be other explanations, but are they actually true, or just convenient?
David Noble
Shorinji Kempo (1983 - 1988)
I'll think of a proper sig when I get a minute...
For now, I'm just waiting for the smack of the Bo against a hard wooden floor....