Socionics functions are the reverse of the MBTI. I am a dyed in the wool INFJ, but the opposing ideas confuse me. I read somewhere that I can't be INFJ Socionics if I am INFJ MBTI? What is the conceptual basis of that?

Bottom line is that I relate most to the INFJ descriptions of all 16 type descriptions regardless of if it's written by Socionics or MBTI proponents, and each individual letter is quite dominant for me in all the tests I take (except F...I typically score 55 F and 45 T or thereabouts, but my I, N, and J preferences are FIRMLY established).