The 1944 Bletchley Park Cryptographic Dictionary

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SECONDARY CIPHER ALPHABET :

The alphabet produced when a primary cipher alphabet is rearranged with its plain component in alphabetical order.

SECTOR CODE :

A German code associated with a particular coastal defence sector rather than with any particular formation.

SELF-EVIDENT :

SELF-STECKERED :

1. (of a letter). Steckered to itself, i.e. unsteckered.

2. (of a menu). Containing or consisting of unsteckered letters.

SELF-STECKERED SELECTION :

Method of setting menus on bombes so that stops only occur when at least one letter on the main chain is self-steckered.

SELF-SUMMING :

(of code-groups). Of which the characters sum to zero.

SEMI-HATTED :

(of code-books). Hatted within definite, and usually small, sections.

SEPARATOR :

A letter or other symbol used to separate words.

SEQUENCE :

(especially). Order of letters in the plain or cipher component of a cipher alphabet, or on wheels of the Wheatstone and Kryha machines.

SPECIAL NUMBER :

One of a series of natural numbers attached to a message as its reference number by its originator, (or by its interceptor, or by any other person who may subsequently deal with it).

SET, v :

1. To find the starting position of (a reciphered code message) on the subtractor.

2. To find the indicators or starting positions of the wheels for deciphering a machine-cipher message.

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