PGL Programmer's Reference Manual

104

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. Be sure to provide sufficient space on the form for the quiet

zones.

Start/Stop Codes

The start/stop code is a unique character identifying the leading and trailing

end of the bar code. The start/stop code is automatically produced with each

bar code. The start/stop code structure permits bidirectional bar code

scanning.

Data Field

The bar code symbol uses a series of varying width bars and spaces to

represent an extensive character set. The bars and spaces vary in width from

one through four modules. Each character consists of three bars and three

spaces that total 11 modules.

Readable Data

The optional readable data field provides a readable interpretation of the bar

code data. It can be printed above or below the bar code symbol.

Check Digit

The modulo-103 check digit is automatically calculated and inserted in the bar

code symbol. The check digit verifies accurate scanning. The start code is

included in the check digit algorithm.