Understanding how the ReadUPCA property works
UPC-A barcodes are a subset of EAN-13. For example, the UPC-A barcode “016000336100” is the same as the EAN-13 barcode “0016000336100”. In fact, UPC-A barcodes are the sub-set of EAN-13 barcodes that start with a 0. The ReadEAN13 property controls whether any barcodes of type EAN-13 are recognized – and this includes UPC-A, whether or not ReadUPCA is set to true. The effect of the ReadUPCA flag is to control whether an EAN-13 barcode that starts with a 0 is returned as a 12 digit UPC-A or as a 13 digit EAN-13 barcode.
In summary,
Settings: ReadEAN13 = false, ReadUPCA= any value
Input: UPC-A 016000336100
Output: nothing
Settings: ReadEAN13 = true, ReadUPCA= false
Input: UPC-A 016000336100
Output: type = EAN-13, value = 0016000336100
Settings: ReadEAN13 = true, ReadUPCA= true
Input: UPC-A 016000336100
Output: type = UPC-A, value = 016000336100
