The anti-tangent phonetic notation method appeared at the end of the Eastern Han Dynasty, which is to annotate another word with two words, take the initials of the upper word and the finals of the lower word, and cut off the pronunciation of the other word. The anti-cutting code was invented on the basis of this anti-cutting pinyin. The inventor was Qi Jiguang, a famous anti-Japanese general and strategist. Qi Jiguang also specially compiled two poems as cipher books: one is: Liu Bian strives for low gas, Berta strives for heaven. Meng Ying speaks with joy, applauds and knows you; Another song is: Spring flowers bloom in autumn, guests sing golden cups, and solitary lamps burn silver altars. In the eastern suburbs, crossing the west bridge, crows remind the morning, bells are set to cover ditches.
These two poems are all the secrets of anti-tangent code. Take the initials of 15 words before the last song and number them from 1 to 15 respectively; Take the vowels of the last 36 words, and the sequence number is 1 to 36. Then the eight tones pronounced at that time were numbered as 1 to 8, so as to form a complete arc tangent code system. How to use it: If the password sent back is 5-25-2, the control initial number is 5 low, the vowel number is 25 west, the initial and vowel of the two words together are di, and the control tone is 2, you can cut out the enemy's characters. Qi Jiguang also specially compiled a "Eight-Tone Meaning Manual" as a teaching material for training intelligence personnel and signalmen.