Kugyŏl

Kugyŏl (also Romanized as gugyeol or kwukyel, among others) is a family of annotation systems for rendering texts written in Classical Chinese into understandable Korean. Believed to have been developed after the introduction of Chinese Characters during the Three Kingdoms period of Korea, its oldest record is found within Buddhist texts in Chinese from the Goryeo period; reached the height of its use during the Joseon dynasty, when readings of the Chinese classics were of paramount social importance.

In kugyŏl, the original text in Classical Chinese was not modified, and the additional markers were simply inserted between words or phrases. Therefore, ignoring the kugyŏl annotations, the text would be readable as regular Classical Chinese.