What it is
Issuer Script Template 1 carries issuer script commands the card must process before the final GENERATE ACApplication CryptogramA cryptogram the card generates to approve or decline a transaction: TC (approve offline), ARQC (go online), or AAC (decline).. Scripts let the issuer update the card in the field — unblocking the application, changing PIN, or adjusting offline limits — piggybacked on the online authorisation response.
Where it appears
Returned by the issuer in the authorisation response; delivered to the card before the second GENERATE ACApplication CryptogramA cryptogram the card generates to approve or decline a transaction: TC (approve offline), ARQC (go online), or AAC (decline)..
Specification reference
Defined in: EMV 4.x Book 3 (Application Specification), Annex A — Data Element Dictionary