PAR, the Payment Account Reference, is an EMVCo-defined value that identifies a payment account across every form the card takes. The plastic card, the same card in Apple Pay or Google Pay, and any tokenized version of it all resolve to the same PAR. It exists so systems can recognize "the same card" without ever handling the card number.
Card-linked loyalty is built on it. When a member enrolls, the PAR of their card is associated with their profile; from then on, a payment with that card in any of its forms can be matched back to the member. The terminal does nothing loyalty-specific, and the shopper presents nothing extra. Recognition happens in the payment data after the tap.
That is both its appeal and its limit. Coverage depends on the card having been linked first and on the acquirer exposing PAR consistently across schemes and markets, so a new card, a partner's card or a corporate card starts unknown. And recognition is all PAR does: it says a known card paid. It does not show a balance, carry a reward, or open a channel to reach the member.
This is where it differs from pass-based identification. Apple VAS and Google Smart Tap hand a loyalty identifier from a wallet pass to the terminal during the tap, which delivers identification, enrollment status, consent and a member-facing surface in one artifact. PAR is the complement, not the rival: use the pass as the program's surface, and card linking, where the payment stack supports it, to attribute the purchases the tap missed.