Ryo took charge of clerical work together with Shiki (ritsuryo system) and Tsukasa mainly under the ministries (Nakatsukasasho, Shikibusho, Jibusho, Minbusho, and Kunaisho).
寮は職_(律令制)や司と共に主に省（中務省・式部省・治部省・民部省・宮内省の各省）のもとで事務を行った。