I have been reading a couple of things lately which have led me to start thinking about how the information gleaned from Enigma and Lorenz decrypts was used. There is no end of stuff on the crypto-analytic side of things but I'm thinking here of how the information was organised. There are references to a card index but no explanation of how it worked. Was there one index or several? How were they indexed? Can anyone point me to a book or site which might cover this?