They hid codes in sheet music, descriptions of chess moves and shorthand symbols disguised as normal handwriting. Postcards were spliced in half, stuffed with wafer-thin notes and resealed.

• 纳粹分子还将密码与五线谱、际象棋棋谱和一些看似常规书写的速记符号结合得天衣无缝。此外，间谍将明信片中间层撕开，将超薄的纸条密封在里面。