TheCodeBreakers
ten top coordinates (the singletons may serve in second position) to
produce 20 two-digit groups. This configuration makes 28 ciphertext
equivalents available for plaintext elements.
It was used in 1937 with keyword M DEL VAYO, the M the initial of
the agent, the DEL VAYO the name of a Spanish Communist. The two
extra spaces were used for a period and a letter-number shift sign:
0987654321
mdel v a y 6 bcf ghuj knp qrstuwxz. /
With this, e = 8, a = 5, b = 10, t = 27, and so on. There will be no
single 2 or 1. The decipherer takes all 1's and 2's as the first digits of a
two-digit group, and joins to it whatever digit follows. He takes any digits
from 3 to 0 as individuals if they are not already part of a pair. Thus the
ciphertext 828115125 can be unambiguously divided as828115125 and
deciphered to Espana.
Other configurations are possible. Seven single digits will permit three
annaabi.ee 
