Cipher is a Chinese word, which means secret signal (using sound, action, etc. ) mutual agreement. From Song Yu Wenbao's Four Notes on Blowing Sword: "The examiner, also ordered by the bribery bureau, went to get it without looking at the words, looking for a secret code."

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Song Yuwen Bao? "Four Records of Blowing Sword": "Examiners are also instructed by the Bribery Bureau to take words without reading them, just looking for the secret code."

"Water Margin" The 30th time: "? Song Wu? I saw these two people winking at the two men with ju knives and making some gestures. "

The thirteenth time in Travel Notes of Lao Can: "Didn't you see that his buddy told Cui Huan to eat vegetables?" That's a code word. "

Xu Chi? One night at the stadium: "He was in the first car and wanted to command the nine cars behind. They have a signal. "