CJK characters
Chinese is written almost exclusively in Chinese characters. It requires over 3,000 characters for general literacy, but up to 40,000 characters for reasonably complete coverage. Japanese uses fewer characters — general literacy in Japanese can be expected with 1,945 characters. The use of Chinese characters in Korea is becoming increasingly rare, although idiosyncratic use of Chinese characters in proper names requires knowledge (and therefore availability) of many more characters. However, even today, students in South Korea are taught 1,800 characters.
A Book from the Sky
The book is composed using a set of 4,000 characters, as this is roughly the number of characters in common usage in modern written Chinese. These characters were designed on the basis of the Kangxi radicals, so that “in terms of density of strokes and frequency of occurrence, they… appear, on the page, to be real characters“. In addition to these, page and fascicle numbers were indicated using tally marks based on the Chinese character 正.