Captain Walter Fried's Fish Notes Annex to #F 71, Screed on Delta D Counts and Colossus runs
Page 8
Tony Sale's
Codes and Ciphers
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8
Runs in common use.
(a) Break-ins 1+2/ Alll links : weaker as the pure
German proportion rises.
Note: 3+4/x is crossed out 3+4/x Fair except when / is common, as
and (3+4)x/ pencilled in in RB, z Gd., Sttick. Stronger
on punctuation as pure German rises.
4+5/ Moderate an all Iinks : best on /-type
messages (RB, Z Gd, Stick). Bad
on pure German.
2+5/ Moderate to feeble on all links
not bad in pure German, bad in
punctuation.
2+4/ Only used in /-type links.
On Colossus I the normaI break-In is to do simultaneously
1+2/ (also on multiple test), 4+5/, 2+5/ and either (3+4)x/ or 2+4/ :
the latter only for /-type links.
On Colossus II (and later Colossi) we do break-ins singly and
on multiple testing. I +2/ - is the invarlable first choice, (3+4)x/ the
second except on /-type links.
The set total is normally taken as 2.5 sigma.
(b) Short runs after Break-in
(i) Given 1 and 2 4=/1=2 ) Only on /-type links.
5=/1=2 )
3x/1x 2 Moderate on all links :~ stronger
with increase of pure German.
3/12 Good on /-type links.
(ii) Given 3 and 4 5+/4,(3+4)x ) Not very fully tested as yet.
5/3x 4 )
1+/3 Good on pure German, rarely successful.
2x/3 4x Dubious.