英文とのリンクを削除しました。
[#241311] Give the password.
Passwords were used verbally during the world wars, when soldiers were returning to camp to make sure that they weren't the enemy.
See these YouTube videos to see examples of spoken passwords.
https://youtu.be/tDy7hFbtGqU?t=24
https://youtu.be/RcVDZiBtX1M?t=11
https://youtu.be/ydNj31qNVFU?t=230
https://youtu.be/NY698TzCGHc?t=331