The article 'hisho gensho no jo' in Zoryo (the Law on Miscellaneous Matters) of Yoro ritsuryo code (code promulgated in the Yoro period) states that 'Onmyoryo should report a good omen or bad omen observed, to the emperor. The reported documents should be gathered for each season, sealed, sent to the Ministry of Central Affairs, and recorded for national history.'
養老律令の雑令には「秘書玄象条」があり、「若し微祥災異有らば、陰陽寮奏せよ。訖らば季別に封して中務省に送り、国史に入れよ」とある。