It used Hanja to represent both native Korean words and grammatical morphemes as well as Chinese loanwords.

The script, which was developed by Buddhist monks, made it possible to record Korean words through their equivalent meaning or sound in Chinese.

[1] The term idu may refer to various systems of representing Korean phonology through hanja, which were used from the early Three Kingdoms to Joseon periods.

The Idu script developed during the Three Kingdoms period of Korea between 57 BC-668 AD.

The Idu script was written in Korean grammatical word order.