Alright, I have some issue with the premise of the F/D notation. So the idea is that their non-standard function patterns imply the possibility of an N/S dominant IXXP or an F/T dominant IXXJ (or an N/S dom EXXJ or an F/T EXXP). The problem that I see with this is that it just seems to be based on the idea that a P is characterized only by preferring to remain open and that a J is classified by preferring closure. I've read very little of what MBTI experts say, but I was under the impression that P and J in reality just serve to clarify function order, in which case any new notation is really pointless because an iNfp is really just an INFJ anyway...only one who supposedly prefers to remain open...which sounds entirely like an entirely subjective interpretation to me, I don't think that these are a totally different class of types.
But nonetheless the whole business of trying to determine my order makes me think that function order is a flawed theory. People are probably a pretty good jumble of their top functions, even with their preferences.