The 1944 Bletchley Park Cryptographic Dictionary
Codes and Ciphers
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2. (in a Vigenere or similar table). Any one of the "vertical" series of letters or other symbols representing the sums, or differences, of the clear letters in the margin and the key-letter at the top, or indicating how the clear letters in the margin are substituted for a particular key-letter.
3. (in reciphered codes). A series of cipher-groups, usually one from each of a number of messages, which have been reciphered with the same subtactor group and so form a vertical series when the messages are written out in depth; also, a vertical series of groups on a subtractor sheet, etc.
4. (in machine and other substitution ciphers). A series of cipher letters or other symbols from the same or different messages which have been enciphered with the same key-letter or the same cipher alphabet and so from a "vertical" series when the messages are written out in depth or (in the case of periodic substitution) when the message or messages are written out on the width corresponding to the period.
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