Engikyaku, a collection of amendments to and enforcement regulations for Ritsuryo (basic national laws), was completed in November 907 (old calendar) during the Heian period and put into force by a senji (written order of the Emperor) in December of the following year (old calendar). Engikyaku at first consisted of 10 volumes, but two additional volumes were soon added to make the total number of volumes 12.
Succeeding Jogankyaku, Engikyaku is a selected collection of particularly important volumes which had been in actual effect at the time of its compilation out of Jogankyaku, so chosen as to comprise imperial edicts and Daijokanbu (official documents issued by Daijokan, the Grand Council of State) during the 39 years from 869 until 907, while its contents were classified by ministry. Although there is no record directly identifying the compilers, the names of persons cited as having participated in the compilation of the extraordinary volumes include FUJIWARA no Tokihira, Sadaijin (minister of the left), serving as the editor-in-chief, FUJIWARA no Sadakuni (Dainagon (chief councilor of state) and Ukone no Taisho or the Chief of Ukonefu, (Guard Department)), Kiyotsura MIYOSHI, Monjo-hakase (teacher of Chinese poetry and history under the Ritsuryo system), Haruyuki OKURA (Minbutaifu, executive officer of the Ministry of Popular Affairs) and FUJIWARA no Yoshitsune, (Myoho-hakase, teacher of the law under the Ritsuryo system), and the staff which compiled the main volumes of Engikyaku are assumed to have consisted mainly of the same persons.
In compiling the new collection, such corrections were made as excluding items already taken up in Koninkyaku or Jogyankyaku and those already abolished at the time of compilation, shortening too long sentences, supplementing insufficient or unclear statements in any earlier Kyaku and, where some rules were partially out of use, clearing the pertinent rules of those unused parts.
Although the original text of Engikyaku is lost, many of its passages are quoted in "Ruiju Sandaikyaku" (a statute book written in the Heian period) and "Seiji Yoryaku" (examples of political affairs in the Heian period) written by KOREMUNE no Tadasuke to enable present-day students to guess substantial contents of the text.
Allocation of Contents to Individual Volumes
Volume 1: Department of Worship and Ministry of Central Affairs
Volumes 2 and 3: Ministry of Ceremonies
Volumes 4 and 5: Ministry of Civil Administration
Volumes 6 and 7: Ministry of Popular Affairs
Volume 8: Ministry of Military Affairs
Volume 9: Ministry of Justice, Ministry of Finance, Imperial Household Department, Imperial Prosecuting and Investigating Office and Kyoshoku (Administrative Agency of Kyoto)
Volume 10: Zakkyaku (Miscellaneous)
Volumes 11 and 12: Rinjikyaku (Extraordinary Volumes) (Supplements)