Printronix ThermaLine Series - Manual (Page 160)

Bar Codes 5–22
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 wide and narrow bars and spaces to
represent standard alphanumeric characters. Each wide or narrow bar or
space is one element; each character in the data field has nine elements.
The structure is three wide elements (bars or spaces) out of the nine total
elements which compose one character.
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 optional modulo–43 check digit can be inserted into the bar code to
verify accurate scanning.