マイクロドット
thumb|NSA photo of microdots taped inside the label of an envelope. The envelope was sent by Operation Bolívar|German spies in Mexico City to [[Lisbon during World War II, but was intercepted by Allied intelligence.]]
thumb|NSA photo of microdots taped inside the label of an envelope. The envelope was sent by Operation Bolívar|German spies in Mexico City to [[Lisbon during World War II, but was intercepted by Allied intelligence.]]
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Discovered by embedding cosine similarity (sentence-transformers MiniLM, 384-dim).