Pillar role and answer type
What it producesalso: pillar_role · atom_role · answer_type · identification · failure mechanism · mechanism · which question · how much questionA typed field that says what kind of answer a pillar, atom or gap question owes: a failure mechanism, or an identification of which things and how much.
Most pillars are failure-mechanism pillars. When the master question asks which things or how much, exactly one pillar carries the identification role: its end-state is that the set the question asks for is identified and its size established, in the question's own terms. The role is carried as data down the chain, because later stages cannot recover the obligation from prose. An identification gap question must include both a which question and a how much question; both halves or the obligation is not carried.