The term 'shiki' of the Shikimoku has means shiki of the Kyakushiki code (amendments and enforcement regulations of the ritsuryo law), while it is allegedly derived from shikijo (code), a form of court noble law which was established to complement Engishiki (an ancient book for codes and procedures on national rites and prayers) that was the last and comprehensive shiki compiled in the Imperial court. The term 'moku' means mokuroku (list) and jomoku (article).
The well-known shikimoku were Goseibai-shikimoku or Joe-shikimoku (code of conduct for samurai) compiled by Yasutoki HOJO, the regent of Kamakura bakufu (Japanese feudal government headed by a shogun), and Kenmu Code compiled by Tadayoshi ASHIKAGA as an administrative policy of the Muromachi bakufu.
Sometimes tsuika ho (additional laws applied after the main code was already established) for the Goseibai-shikimoku was also referred as 'shikimoku.'
Thus the shikimoku, and the Goseibai-shikimoku in particular, were considered as fundamental laws for samurai government, and a view that the shikimoku was equal to Bukeho was generally accepted.
From the historical point of view, however, the shikimoku meant the compilation of shikijo (code), a court noble law. It became evident that provisions for the Goseibai-shikimoku was in accordance with the law formula for the court noble law of the early Kamakura period, which had changed corresponding to the social reality, actually by adding to a new system and Myobo kanmon (written reports to the Imperial Court by scholars of the law). That was because the Goseibai-shikimoku was not directed to the general law in samurai society, but it was also intended to evade legal conflicts between the samurai and court noble society. According to 'Yasutoki shosokubun' (a letter of Yasutoki HOJO), since the court noble law had been described in Chinese classics and is difficult to be understood, a law written in a style easily understood by samurai was made, meaning that the court noble law was reconstructed and altered to be more understandable for the samurai. In shikimoku the section of so-called 'reason in the samurai society' regarding incomes from land taxes on shoryo (territory), Nenkiho (a legal principle for the statute of limitations on land in possession) and so force were clearly described, while only indirectly mentioned in the form of proviso, details, and article of exceptions. That was supposedly because, as Yasutoki mentioned in the 'shosokubun,' he never meant to create a new legal system but contemplated a legal order based on the court noble law and harmony in the samurai society, therefore the Goseibai-shikimoku were the regulations and notes required to achieve this goal.
It has been believed that the reason why Yasutoki studied "Hososhiyo-sho" (a legal book compiled by the Sakanoue clan between the end of Heian period and the early Kamakura period) as well as the criterion of Myobodo (study of Codes) (legal documents of petition, petition for objection, and so forth) and why his uncle Tokifusa HOJO, a bakufu rensho (assistant to regents in bakufu) who had worked as Rokuhara Tandai (an administrative and judicial agency in Rokuhara, Kyoto) with him and person who had come from lower-ranking government official in Kyoto and their descendents participated in the compilation were that he sought the source of law not for the common law for samurai families, but for the court noble law. This tendency was to be further increased in the Kenmu Code of the Muromachi bakufu which placed its center in Kyoto, the central place of the court noble law. Like the court noble law, the Kenmu Code put forward 'thrift' and 'decorum,' and further put Goseibai-shikimoku in its main position of the source of law as 'main code,' thus reportedly bugyonin (a magistrate) always had Goseibai-shikimoku even in the actual lawsuit. That was because the Goseibai-shikimoku was comparable to the court noble law and widely accepted in the society since it incorporated the legal conception and 'tokuchi' doctrine (a doctrine for administration based on moral or humanity) common to the samurai law and court noble law. That was pointed out by the facts that Shikimokusho (a commentary on Goseibai-shikimoku) was compiled during the Sengoku period (period of warring states) of Japan, that the designation of 'shikimoku' was used for bunkokuho (the law individual sengoku-daimyo enforced in their own domain), and that many commentaries were written for it as well as it was used for a textbook for writing in the Edo period when a new system of law for samurai government was established.