I could probably find this out if I looked it up, but I thought maybe some people here could summarize it fairly easily.
Why are the types broken down into the categories of NF/NT and SP/SJ? Why not NF, NT, SF and ST? Or NP, NJ, SP and FJ? It seems kind of inconsistent that Ns are categorized with the F/T and Ss with P/J. But I'm sure there's a good reason for it!