Jim Reeds has come back with the following comment:

"Although when used in the 1940s the 5 letter groups of Cypher 5 were not used, I've been looking at them. They all obey a check-sum equation, sum-of-letters = constant, but not all such words are used.  Is there a small list of rules for excluding possible groups so that the ones that are left are exactly the ones used?"


I've put up all that seemed relevant, however, Pages vi, vii, viii and 1 are doubly edited.  Firstly there is overwriting in dark blue ink and also they have a typewritten insert glued on top of them (detectable by the larger typeface).  Nothing like you mention is visible and even after closer examination, nothing else can be discerned.

Front cover, title page and contents pages

Instructions for use

Codebook proper

Dates and numbers

Spelling system



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