The types they found by analyzing a large number of individuals answers to questions based on the Big Five Personality traits, a system that is empiric.
They found 4 types of people in their study of UK and USA people: reserved, role models, self-centered, and average. NPA types of individuals are Narcissistic, Narcissistic Perfectionist, Aggressive, Aggressive Perfectionistic, and Narcissistic Aggressive Perfectionistic all these with subtypes .
NP and PA are clearly reserved. NPA are clearly role models, and the N, the A, and the NA types are self-centered. Average seems to be a wastebasket term for many individuals whom their system isn't able to characterize for whatever reason.