People who spend their life investing on Socionics, the history of socionics, were started from Infromation Elements, which then to model A and then to intertype relationship. I think the next step MUst be INfusing Enneagram together to further more upon Intertype relationship. I think most of you here know that. It just click in my head that my Dual, the ISTj is not my dual but the ISTj with instinct stacking SO/SX, which is identical to my stacking. An ISTj I know whose stack begins with an Sp and I wont be able to develop a relationship like what the Dual descrption is suspose to be, People must know that since most people think Duals are overrated yet still believe that it is true. WHY? i can explain and it is because they might have met one or two whose enneagrram of their dual align a match with their own enneagram type, there provide perfect duality.(I think however enneagram type has less of importance as the Instinct stacking)