Lexmark T656 Technical Reference Manual page 60

c Product Code: The product code is a unique code assigned by the manufacturer. Unlike
the manufacturer code, which must be assigned by the UCC, the manufacturer is free to
assign product codes to each of their products without consulting any other organization.
d Check Digit: The check digit is an additional digit used to verify that a bar code has been
scanned correctly. Since a scan can produce incorrect data due to inconsistent scanning
speed, print imperfections, or a host of other problems, it is useful to verify that the rest of
the data in the bar code has been correctly interpreted. The check digit is calculated
based on the rest of the digits of the bar code. Normally, if the check digit is the same as
the value of the check digit based on the data that has been scanned, there is a high level
of confidence that the bar code was scanned correctly.
2
UPC-E (including +2 and +5 variants)
UPC-E is a variation of UPC-A which allows for a more compact barcode by eliminating
"extra" zeros. Since the resulting UPC-E barcode is about half the size as an UPC-A barcode,
UPC-E is generally used on products with very small packaging where a full UPC-A barcode
couldn't reasonably fit.
A UPC-E code is contains:
• Left-hand guard bars, or start sentinel, encoded as 101.
• Six data characters, encoded from the parity table above.
Composite bar codes
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