[hakfoo]

With cards, merchants can theoretically pass additional data to identify a purchase order number, or even distinct line items (30 red widgets at $6.34 each), but it's only offered for corporate cards.

I'm surprised there's no way to opt-in as a consumer, or that some middleman doesn't want to really push it to gain more data to mine.

I think on a practical basis, though, it's flagged by the BIN (the first 6 or 8 digits of the card number)-- if it's not in a known commercial-card range, the data might not get sent upstream, so random users turning it on wouldn't work.