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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 Code
Unique start and stop codes permit bidirectional scanning. Both start and stop
codes contain bars and spaces. They are automatically produced.
Data Field
The bar code symbol uses a series of wide and narrow bars and spaces to
represent each numeric character. The structure is four wide elements (bars
or spaces) and four narrow elements. Each character contains four data bits,
with each 0-bit made up of a narrow bar/wide space arrangement and each 1-
bit made up of a wide bar/narrow space arrangement.
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
If specified, the modulo-10 or modulo-11 (or both) check digit is automatically
calculated and inserted in the bar code symbol. The check digit verifies
accurate scanning.