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Continue to ChatQuery : Are there typographic methods of rendering a document traceable? I seem to recall an anecdote on how one branch of the British government had designed a way to circulate seemingly identical for-your-eyes-only https://vmapp.org/query/9048/Are-There-Typographic-Methods-Of-Rendering-A-Document-Traceable-I-Seem-To-Recall-An-Anecdote-On-How-One-Branch-Of-The-British-Government-Had-Designed-A-Way-To-Circulate-Seemingly-Identical-For-Your-Eyes-Only/