Der zuvor gezeigte Beleg zeigt die für Codierungen in GB zu dieser Zeit üblichen blauen Punkte = blue dots.
Hier findet man folgende Informationen dazu:
http://www.davros.org/postcodes/ukbluedots.html"In its original form, this system consists of two rows of blue dots on the envelope.
Each row contains 13 dot positions plus an index dot at the right hand end; the dots are a quarter of an inch apart with the index dot about three-quarters of an inch from the right hand edge of the envelope.
The lower row (about half an inch above the bottom edge) represents the outward code, and the upper row (two inches higher) the inward code:
The 13 bits of each code represent a number from 0 to 4095.
The leftmost bit is a parity check (there should be an odd number of dots or bars), while the remaining 12 have values, from left to right, of 32, 16, 8, 4, 2, 1, 2048, 1024, 512, 256, 128, and 64.
Outward codes
It would appear that each of the 124 areas is given a base number, and then the district number is added to that.
Thus the base for CB is 2286, and so CB1 is coded as 2287, CB2 as 2288, and so on.
The following table lists the deduced base values for each area checked, and those districts used to deduce them. More data is needed.
Area Base
CB 2286
IM 2693
ME 4066
N 1903
NP 445
NR 2982
RG 3589
SN 1969
W 2018
WD 2309
Inward codes
To represent the inward code, each character is given a value and these three values are added together.
Because of the two reserved codes, the value of the digit is expressed as a value for the range of the code.
Range: Basic Value
0AA to 0ZZ: 3667
1AA to 1ZZ: 65
2AA to 2ZZ: 465
3AA to 3ZZ: 865
4AA to 4FZ: 1265
4GA to 4ZZ: 1266
5AA to 5ZZ: 1666
6AA to 6ZZ: 2066
7AA to 7SE: 2466
7SF to 7ZZ: 2467
8AA to 8ZZ: 2867
9AA to 9ZZ: 3267
A B D E F G H J L N
first 0 20 40 60 80 100 120 140 160 180
last 0 1 2 3 4 5 6 7 8 9
P Q R S T U W X Y Z
first 200 220 240 260 280 300 320 340 360 380
last 10 11 12 13 14 15 16 17 18 19
For example, the inward code 3149 = 2867+280+2, and so represents 8TD.