5525B/31/32 Line Matrix Printer Code V Programmer's Reference Manual

194
Chapter 3 Bar Codes
Quiet Zone
Both ends of the bar code structure require blank quiet zones. The quiet
zones must be at least 0.25 inches wide and completely blank to ensure
accurate reading of the start/stop codes and to prevent adjacent bar codes
from overlapping. You must provide sufficient space on the form for the quiet
zones.
Start/Stop Codes
The start and stop codes identify the leading and trailing ends of the bar code.
UCC/EAN-128 uses unique start codes for character subsets B and C, and a
stop code common to both. An automatic mode switching feature is used to
generate the correct start code based on the first four data field characters.
Data Field
UCC/EAN-128 bar codes require a special character called “Function 1”
(FNC1) to immediately follow the start code. Code V automatically supplies
this character, so it must not be included in the data field by the user.
A character is made up of three bars and three spaces, each varying in width
from 1 through 4 modules, for a total of eleven modules. The number of
modules making up the bars is even. The stop code has four bars and is 13
modules wide.
The character set for UCC/EAN-128 is the same as the character set for Code
128, which is shown in Table 26. Every character is interpreted according to
the currently active character subset. UCC/EAN-128 uses subset B and
subset C only. Subset B includes all standard alphanumeric keyboard
characters, lowercase alphabetical characters, and special characters.
Subset C interprets the characters as pairs of numbers 00 through 99, along
with some special characters as shown in Table 26. The start code or subset
switch code determines whether a particular bar code character is decoded
as one character or as a pair of numbers.
Do not use characters from the Alternate subset with the UCC/EAN-128 bar
code. These are two character sequences starting with the “greater than” (>)
symbol, which are used in the C128 bar code to provide manual mode
character subset selection and inclusion of special characters such as FNC1.
Readable Data
The optional readable data field provides a human-readable interpretation of
the bar code data. When the readable data field is enabled, the overall height
of the bars is reduced to make room for a guard band and the human-
readable characters. The readable data field will be formatted with spaces or
parentheses denoting particular data fields such as the application identifier.
Special characters such as start, stop, subset switch, modulo-103 check digit,
and FNC1 do not appear in the human-readable data.