In the early days of the United States’ atomic weapons program, all information and documents produced by the Atomic Energy Commission were classified. This simplified the task of determining classification, even if meant that the lunch menu ended up being classified. Over time, however, some of the information became public knowledge and no longer needed to be protected. Keeping track of classified and unclassified information and making sure everyone used the same rules for classification became more and more difficult. Thus, classification guides were born.

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