Gukyoku

...These terms, such as "A, B," "Jyo, Chu, and Gyo," "Shiyojuu, Dui, and Triple," indicate the range and melodic form, and are the basis of the melodic structure of so-called narrative music from the Middle Ages onwards. (2) Rhythm In Tendai Shomyo, unequal rhythms are called "overtures," and equal rhythms are called "teikiyoku," and both types and intermediate ones are called "gukiyoku" and "hakiyoku." In teikiyoku, the rhythm is broadly divided into four types, and it is noteworthy that it includes a triple beat, which is very rare in Japanese music. ...

*Some of the terminology explanations that mention "kukyoku" are listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…これは〈甲･乙〉〈上･中･下〉〈初重（しよじゆう）･二重･三重〉などの用語で音域，旋律形態を指示するもので，中世以後のいわゆる語り物音楽の旋律構造の母胎となっている。(2)リズム　天台声明ではリズムは不等拍のものを〈序曲〉，等拍のものを〈定曲（ていきよく）〉とし，この両様や中間的なものを，〈俱曲（ぐきよく）〉〈破曲（はきよく）〉と称する。定曲では拍子が4種類に大別され，その中に日本音楽ではたいへん珍しい3拍子が含まれているのが注目される。…

※「俱曲」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典 第２版について | 情報