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UPC-A Preamble
A preamble is a lead-in character for UPC-A symbols transmitted to the host device. The lead-in characters are considered
part of the symbol.
Data is sent to the host in the following format:
Select an option by scanning one of the bar codes shown below.
No Preamble [data]
System Character [schar] [data]
System Character and Country
Code
[country code] [schar] [data]
No Preamble
* System Character
System Character and Country Code (“0” for
USA)