千字文
The Chongtong was the term for Joseon-era gunnery. There were many different types, various improvements over the years, often including renaming. The well-known "Cheonja", "Jija", "Hyeonja", and "Hwangja" were named after the first four characters of the Thousand Character Classic in decreasing size, thus making them equivalent to Cannons A, B, C, and D.