Subject Description


Transmission of messages

OCM Identifier


Subject Description

This category is used for to index information on the technologically simple transmission of messages. The category includes information on signaling devices (e.g., fire, smoke, blinker, semaphore); signal codes (e.g., drum language, flag codes, Morse code); cryptography; use of carrier birds and animals; messenger and human courier systems; etc. For information on more technologically advanced transmission of messages use "Mail" (205), "Telephone and Telegraph" (206), "Radio and Television" (207), and "Internet Communications" (2010).


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