Codabar; Codablock - Intermec CK60 User Manual

Chapter 6 — Bar Code Symbologies

Codabar

Codablock

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Codabar was for retail price-labeling systems. Today it is widely accepted
by libraries, medical industries, and photo finishing services.
Codabar is a discrete, self-checking code with each character represented by
a stand-alone group of four bars and three intervening spaces.
Four different start or stop characters get defined and designated "a", "b",
"c", and "d". These start and stop characters are constructed using one wide
bar and two wide spaces. A complete Codabar symbol begins with one of
the start or stop characters followed by some number of data characters and
ending in one of the start or stop characters. It may also contain optional
check digit before each stop character.
Any of the start or stop characters may be used on either end of the symbol.
It is possible to use the 16 unique start or stop combinations to identify
label type or other information.
Since Codabar is variable-length, discrete, and self-checking, it is a versatile
symbology. The width of space between characters is not critical and may
vary significantly within the same symbol. The character set consists of "0"
through "9", "-", "$", ":", "/", ".", and "+".
The specific dimensions for bars and spaces in Codabar optimize perfor-
mance of certain early printing and reading equipment. Codabar has 18
different dimensions for bar and space widths. So many different dimen-
sions often result in labels printed out of specification and cause Codabar
printing equipment to be more expensive.
Codablock is a stacked symbology from ICS Identcode-Systeme. It was
invented by Heinrich Oehlmann and was originally a stack of Code 39
symbols.
Each Codablock symbol contains from 1 to 22 rows. The number of char-
acters per row is a function of the x-dimension of the symbol. In other
words, each row can contain a variable amount of characters. Each symbol
has a start and stop bar group that extends the height of the symbol. Each
row has a two character row indicator, and the last row of the symbol has an
optional check digit. The symbol printing program must calculate not only
the number of rows needed as in the other stack symbologies, but also cal-
culate the number of characters per row and the print density necessary to
best fit the data into the Codablock symbol.
The code is a continuous, variable-length symbology that can encode the
Code 39 character set (10 digits, 26 letters, space, 6 symbols) and is as
dense as a Code 39 symbol at a given print density. For example, the maxi-
mum data density is 56 alphanumeric characters per square inch with a
symbol using an x-dimension of about 7.5 mils and a bar ratio of 2 to 1.
CK60 Series Handheld Computer User's Manual