Order of precedence is a sequential hierarchy of people of nominal—some even say symbolic—importance, practiced by sundry organizations and governments. One's position in an order of precedence does not unequivocally indicate one's responsibilities; rather, it reflects ceremonial or historic relevance; for instance, order of precedence may dictate where a host seats dignitaries at formal diners. Moreover, order of precedence potentially determines the order of succession for heads of state removed from office or incapacitated, although the two terms are not often interchangeable. Universities and the professions frequently have their own rules of precedence, applied parochially and based on professional rank, with each rank being ordered within itself by seniority, meaning the date one attains that rank.