Card with an unexpected extra data field
I've seen this pop up a few times. If the extra field doesn't throw the checksum validation, honestly, most scanners just ignore it. The first thing I'd check is whether the barcode is dead or missing a proper separator before that tag. If you're testing against something like Intellicheck database, that extra data could throw a red flag on AAMVA compliance if it's in an area it shouldn't be. A quick fix is converting to a PDF417 string format and running a hex dump to see what's actually there.
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Received a card where the PDF417 barcode contained a field I had not submitted — a field labeled with a field identifier I did not recognize that appeared to contain a randomly generated string. Spent time figuring out what this was and whether it was a problem.
What the unknown field was
After looking up the AAMVA PDF417 data dictionary, I identified the field as a jurisdiction-specific additional field. AAMVA's standard includes space for each state to include state-specific data beyond the core required fields. Some states include things like organ donor status, veteran indicators, or internal state processing codes in these optional fields. The field in my card contained a string that matched the pattern for a state-specific internal identifier used by that state's DMV system.
Is this a problem?
Not necessarily. A venue scanner that decodes the barcode and displays fields will show this field if it reads it, but most venue scanner apps only display the fields they are programmed to format and show — state-specific fields typically display as "additional data" or are ignored. No inconsistency between the extra field and the card face is introduced since the extra field is not displayed on the card face.
The more meaningful question is whether the value in the field is a plausible value for that field. A field that contains a plausible-format value consistent with that state's data structure is less concerning than one containing obviously random or nonsensical data.
What I confirmed
The vendor confirmed they intentionally populate this field with a format-consistent value. Knowing this is intentional and understanding why made the concern go away. If you see unexpected fields, checking the AAMVA data dictionary and asking the vendor is the right approach.
Unexpected data fields in a decoded barcode are most commonly jurisdiction-specific optional fields that some scanner apps display and others suppress. The AAMVA standard defines a base set of mandatory fields and a larger set of optional fields that states may implement. A card with correctly encoded optional fields that happen to display in your scanner app is not defective — it is correctly implementing the full AAMVA specification for that jurisdiction.