8A

Authorisation Response Code is the two-character verdict on the whole transaction: approved, declined, referral, or one of several other outcomes the issuer's host communicates back after an online authorization request. It's terminal-supplied in the sense that the terminal receives it from the acquirer/issuer and then feeds it into the card's own logic for the second GENERATE AC, alongside the related Issuer Authentication Data (91) the issuer may also return and the CVM Results (8E) the terminal has already recorded - the card uses the ARC to decide what its own final cryptogram should say, since a card that went online for a decision needs to know what that decision actually was before it can respond appropriately. A terminal that mangles or misroutes the ARC on its way from the host to the card - a common integration bug at the acquirer-connectivity layer - produces a transaction where the host's own records say one outcome while the card's final cryptogram reflects a different one, which is exactly the kind of discrepancy a reconciliation process is built to catch, not something visible from the terminal's receipt alone. See EMV 4.4 Book 3 and Book 4.