ID Tech ValueScan II User Manual page 37

UPC-A
Supplement digits: The Supplement digits barcode is the
supplemental 2 or 5 characters for UPC code.
Format
Supplement Digits
Leading Data Digits Check
2 or 5 or
Zero (11 Digits) Digit
128
UCC / EAN
Truncation / Expansion: The leading "0" digits of UPC-A
data characters can be truncated when enabled.
Supplement Check Counter: It will be more reliable to read
the barcode with the extension (supplement) like UPC-E/A or
EAN-8/13, but it will slow down the decoding speed when this
counter is set.
36