[1] The hyangchal writing system is often classified as a subgroup of the Idu script.
[2] The first mention of hyangchal is the monk Kyun Ye's biography during the Goryeo period.
Twenty-five such poems still exist and show that vernacular poetry used native Korean words and Korean word order, and each syllable was "transcribed with a single graph".
The practice of hyangchal continued during the Goryeo era, where it was used to record native Korean poetry as well.
[3] The following example is the first verse of the poem Cheo Yong Ga (처용가; 處容歌).