Rule
The first letter (I or E) indicates the trend (internal - external) of the 4 functions. If it is Exxx, the set of functions will be E-I-E-I. Otherwise, if it is Ixxx, the function set will be I-E-I-E
Cause: type E will show their most dominant out. What outsiders can clearly see is their signature trait. Go back to type I, what outsiders see only as auxiliary. Because the signature trait they hide inside.
The 2nd (N or S) and 3 (F or T) letters indicate what the first 2 functions are. For example, xNFx would be N & F. And xSTx would be S & T being the first 2 functions.
The last letter (P or J) indicates that the first extrovert function is perceiving or judging. If it is xxxP, then 1 of the first 2 functions will be Ne or Se. If it is xxxJ, then one of the two functions will be Te or Fe.
We have the opposite functions dominant <> interior ; auxiliary <>tertiary
has four opposing function pairs: Si <> Ne Ni <> Se Ti <> Fe Fi <> Te
A stack is made up of two function pairs. Depending on the position, it manifests differently (strong or weak). Each such combo will form an inner world of a PT.
Ex: ENFJ
1 Fe 2 Ni 3 Se 4 Ti
