Printronix ThermaLine Series - Manual (Page 217)

5–79 Bar Codes
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. Be sure to provide sufficient space on the form for the quiet
zones.
Start/Stop Codes
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 numeric characters. The structure is 2 wide elements (bars or
spaces) and 3 narrow elements. In the bar code, two characters are
interleaved (paired); bars are used to represent the first character in the pair
and spaces are used to represent the second character in the pair.
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-10 check digit can be inserted into the bar code to verify
accurate scanning. For the German variation of I-2/5, the checksum digit is
always automatically calculated and inserted.