Both were based on apocryphal books using Saicho, Kukai, etc. as a pretext for selectors, and were instructed as secrets of each shrine, or in some cases, became known among people through Shugendo (Japanese mountain asceticism-shamanism incorporating Shinto and Buddhist concepts).
いずれも、最澄・空海などに選者を仮託する偽書によっており、各神社の秘伝として伝授され、また一部は、修験道などを介して民間にも知られていった。