Introduction
The Royal Mail 4-state Customer Code(RM4SCC) is a height-modulated
barcode symbology for use in automated mail sort process. There are 38
valid characters in the entire character set:
- numeric characters 0-9;
- alpha characters A-Z;
- open and close brackets ( and ) or [ and ] (only used as start/stop
bars)

Complete RMS4CC character set
Each RM4SCC character consists of four bars, of which two are ascenders
and two descenders. The track element is present in all bars.

Structure of a RM4SCC symbol
A complete RM4SCC is made up by a set of distinct bars and spaces for
each character, followed by a checksum character and enclosed by a unique
Start bar, Stop bar and a quiet zone. The start bar and stop bars are
unique and different; thus enable the symbol to be read in any direction.
The quiet zone must be at least 2mm in each direction.

Checksum Character Calculation
The checksum character is printed on the right hand of data characters
to provide error protection.
To calculate the checksum character, perform the following steps:
|
RM4SCC Checksum Calculation Table |
|
|
Column |
|
Row |
1 |
2 |
3 |
4 |
5 |
0 |
|
1 |
0 |
1 |
2 |
3 |
4 |
5 |
|
2 |
6 |
7 |
8 |
9 |
A |
B |
|
3 |
C |
D |
E |
F |
G |
H |
|
4 |
I |
J |
K |
L |
M |
N |
|
5 |
O |
P |
Q |
R |
S |
T |
|
0 |
U |
V |
W |
X |
Y |
Z |
- Calculate the upper half and lower half values for each data
character. A character splits horizontally into an upper half and a
lower half. From the right to the left assign each bar a weight. The
rightmost bar has a weight of 0, and the second rightmost 1, and third 2
and the leftmost 4.
- Based on absence of an ascender and descender, assign a multiplier to
each bar. For the upper half, if the ascender is present, the multiplier
is 1 otherwise is 0.
- Multiply the weight and multiplier for each half. Sum together to
produce the combination value for each half. If the combination value
equals six the value goes back to zero.
- Sum all the values calculated in step 3 to produce upper half and
lower half combination totals. Dive each half total by six to get the
remainder.
- Look up the table below, use the combination value of upper half as
the row reference, the combination value of lower half as the column
reference.
Note that the checksum algorithm is only performed on the main data
characters contained the code. The Start and Stop bar do not participate
the checksum calculation.
Barcode Format
The customer barcode must be a continuous string of characters and must
not include white space characters. The code density is 20 to 24 bars per
2.54 cm (20 ~ 24 bars per inch). For detailed requirement on barcode placement and printing
requirement, please refer to
UK postal office .
Web Tool
At barcode knowledge library we provide free web-based utilities for
readers to calculate check digits, performing number conversions. To
calculate RM4SCC check digit, refer to this page. If you have
purchased Morovia Royal Mail Fontware, you may consider checking out
this
page for additional utilities.
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