Code Names. Memo. By Inter-Services Security Board

4. The Admiralty have suggested that a printed list of words available for use as code names should be prepared and circulated on a fairly wide basis (in the case of the Navy to almost every holder of Admiralty cipher tables). As the list would not contain interpretations this should not endanger security. 5. Secondly, to facilitate ciphering, a four-figure numeral group would be printed against each word. 6. Thirdly, the list would be divided into blocks numbered in sequence. A key to these blocks showing to whom each block had been allotted would be distributed on a very restricted circulation.