63. Select two of the Book Indicator Groups provided for Enigma
general Procedure in the K-book; and of these, enter the Cipher
Indicator Group as the first Book Group and the Procedure Indicator
as the second Book Group on the cipher form.
Do not forget to leave the space for the dummy letter.
In order to expedite cipher service, cipher forms with en-
ciphered indicator groups written on them are to be kept ready for
outgoing messages. The Message Cipher is to be written on too
and the date of validity to be noted.
64. Read the plain text through and then, beginning in the third
line of the column entitled "Book Groups", enter the text onto the
cipher form in four-letter groups. If necessary, fill the last
group out to four places, with attention to the section above,
entitled "Preparation of the Plain Text" ( see paragraphs 5 ff. )
65. Set in the valid Cipher of the Day (including the basic setting)
for Enigma General Procedure and push down the keys for the Procedure Indicator Group (Book Group) once. The result is the Message Cipher.
66. Set in the Message Cipher and encipher the "Book Groups" con-
secutively from the third line on. Enter the resulting letters
as four-letter groups in to the "Radio Groups" column, one group
to a line, writing from left to right. The indicator groups do
not get enciphered along with the others.
67. Check by ciphering the message back again.
68. Fill out and encipher the Book Indicator Groups according to
the cipher procedure for Indicator Groups in the K-Book. Enter
the resulting cipher letters in the "Radio Groups" column as first
and second groups and in the same order as next-to last and last
groups. Check by ciphering the indicator groups back.
69. Prepare the message for sending:
a) Addresses and signatures -- only in general radio procedure.
b) Time group -- date end serial number to complete it.
c) Group count -- radio groups including radio indicator groups.
The following SSD-message with time group l053 is to be sent
in Fleet Procedure on the 3rd August:.
SSD To Fleet, Cruiser "Koeln". Position bearing of 160 degrees
to Norderney Lighthouse three miles distant. Going
with T l53 to square 9551 left top.