Gishiki (Book) (儀式 (書物))
Gishiki originally meant court rule and customs in official duties and ceremonial functions at the imperial court under the ritsuryo system, and later, compilations and books for prescribing court rule and customs came to be called 'Gishiki.'
Some said that the Sandai Gishiki (three major Gishiki books) were compiled in parallel with Sandai Kyakushiki (Laws and Regulations of the three reigns) in the Heian period, but recently, others have questioned that opinion.
Summary
After the Taika Reform, various systems, functions, and formalities influenced by Tang models began to be introduced, and various rules and customs began to be prescribed. Gishiki meant the rules and customs in their original sense. According to "Shoku Nihongi" (Chronicle of Japan Continued), Chogi no rei (ceremonies in the imperial court) was decided in 698, and Shakuten no rei (also referred to as Sekiten no rei; a festival to Confucius and his disciples) was decided in 748.
However, to cope with increasing new rules and customs, a method of codifying and improving the prescription of the rules and customs was developed.
The final compilation of rules and customs was called 'Gishiki.'
It was considered that 'Gishiki' modeled after the Book of Etiquette and Decorum, a compilation of decorum in Tang -- Japanese 'Gishiki' was specialized exclusively in rules and customs inappropriate to be specified in law by omitting the parts that overlapped with ritsuryo kyakushiki (Laws and regulations). Conversely, Koninshiki (Palace regulations of the Konin era) and Engishiki (Palace regulations of the Engi era) stated in their prefaces that descriptions of formalities were omitted. In contrast, Joganshiki (Palace regulations of the Jogan era) stated in the preface (presently contained in "Ruiju kokushi" - Classified National History) that the prescription of rules and customs was provided separately from shiki (Regulations) -- 'Jogan Gishiki' (or, simply "Gishiki") was considered to be that prescription.
On the other hand, it was believed that Kotaishiki (Administrative transition regulations) and 'Gishiki' were compiled at the same time as the compilation of the Kyakushiki, and it was formally believed that there had been the Sandai Gishiki, which was composed of 'Konin Gishiki,' 'Jogan Gishiki,' and 'Engi Gishiki.'
Nevertheless, it was considered that 'Dairi shiki' (Palace regulations) and 'Dairi Gishiki' (Book on outline of ceremonies) were compiled during the Konin era and the Gishiki titled 'Konin Gishiki' did not exist. As for 'Engi Gishiki,' although the part believed to be a surviving fragment of it remained, no records existed to prove that it was used for virtual functions in the imperial court; therefore, some say it was an incomplete work or a pretense made in later ages. Accordingly, only 'Jogan Gishiki' was confirmed to have existed, but there was still another view that it was simply titled "Gishiki;" therefore, it is unknown whether the title 'Jogan Gishiki' was virtually used or not. The above indications, however, merely denied that the Sandai Gishiki corresponding to the Sandai Kyakushiki were neither compiled nor did they exist, and it was still accepted that both the compilation of Kyakushiki and the compilation of 'Gishiki' were projects taken for complementing the ritsuryo law and that compilation of the Kyakushiki had some relationship to the compilation of Dairi shiki and Jogan Gishiki each of which were a single project.
As 'Gishiki' which might have been virtually effective, 'Dairi Gishiki' which was compiled almost simultaneously with 'Dairi shiki,' the completion of which was reported to Emperor Saga in 820 (it was unknown which of them was completed first), then 'Jogan Gishiki' ("Gishiki") which was compiled in the Jogan era, and 'Shingishiki' which was made during the tenure of Emperor Murakami, were known. After the mid Heian period, privately compiled 'Gishiki' such as "Saikyuki" (also referred to as Seikyuki and Saiguki; a work outlining court rules and customs) and "Hokuzansho" (manual of court rules and customs) began to be created.