Printronix ThermaLine Series - Manual (Page 196)

Bar Codes 5–58
Quiet Zone
Both ends of the bar code structure have 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. The IGP/PGL automatically produces the left quiet zone; be
sure to provide sufficient space on the form for the right quiet zone.
Start/Center/Stop Codes
The start/center/stop codes are special character codes marking those
portions of the bar code. These codes are automatically provided.
Data Field
The bar code symbol uses a series of varying width bars and spaces to
represent a limited character set (numbers 0–9 and Special Characters Start,
Center, and Stop). The bars and spaces vary in width from one to four
modules. Each character consists of two bars and two spaces that total
seven modules. The symbol coding of the left data field is different from
the right data field to permit read direction sensing.
The optional 2– or 5–digit add–on data, placed within the delimiter at the
end of the bar code, typically identifies a periodical issue number or price,
respectively.
Readable Data
The human readable data field provides a readable interpretation of the bar
code data. It can either be suppressed or printed below the bar code symbol.
Check Digit
The modulo–10 check digit is automatically calculated and inserted in the
bar code symbol. The check digit verifies accurate scanning.