Printronix LQH-HWTM - Manual (Page 192)

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Chapter 3 Bar Codes
Quiet Zone
Quiet zones extend on both ends of the bar code to permit the scan to begin
and end in a blank area. The IGP automatically produces an 11-module wide
left quiet zone. You must provide sufficient space (minimum of seven
modules) on the form for the right quiet zone. The number system character is
also printed automatically in the left quiet zone.
Start/Stop Codes
The start/stop codes are special character codes marking those portions of
the bar code. These codes are automatically provided.
Number System Character
The number system character field for all UPC-E and UPC-E0 bar codes must
be zero.
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
and Stop). The bars and spaces vary in width from one through four modules.
Each character consists of two bars and two spaces that total seven modules.
For UPC-E, eleven digits are expected, which are compressed down to the
six encoded symbol characters. For UPC-E0, six compressed digits are
expected.
The optional 2- or 5-digit add-on data field is placed at the end of the bar code
and 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 above or 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. The number system
character is included in the check digit algorithm.