Editing EMV (section)

===Terminal action analysis===
The results of previous processing steps are used to determine whether a transaction should be approved offline, sent online for authorization, or declined offline. This is done using a combination of [[data object]]s known as ''terminal action codes'' (TACs) held in the terminal and ''issuer action codes'' (IACs) read from the card. The TAC is [[Logical disjunction|logically OR'd]] with the IAC, to give the transaction acquirer a level of control over the transaction outcome. Both types of action code take the values Denial, Online, and Default. Each action code contains a series of bits which correspond to the bits in the [[Terminal verification results]] (TVR), and are used in the terminal's decision whether to accept, decline or go on-line for a payment transaction.  The TAC is set by the card acquirer; in practice card schemes advise the TAC settings that should be used for a particular terminal type depending on its capabilities.  The IAC is set by the card issuer; some card issuers may decide that expired cards should be rejected, by setting the appropriate bit in the Denial IAC. Other issuers may want the transaction to proceed on-line so that they can in some cases allow these transactions to be carried out.<ref>{{citation
  |url=https://www.abbreviationfinder.org/acronyms/tac_terminal-action-code.html
  |title=TAC Definition: Terminal Action Code}}</ref>{{better source|date=July 2022}} 

When an online-only device performs IAC-Online and TAC-Online processing the only relevant TVR bit is "Transaction value exceeds the floor limit". Because the floor limit is set to zero, the transaction should always go online and all other values in TAC-Online or IAC-Online are irrelevant. Online-only devices do not need to perform IAC-default processing. An online-only device such as an ATM always attempts to go on-line with the authorization request, unless declined off-line due to IAC-Denial settings. During IAC-Denial and TAC-Denial processing, for an online only device, the only relevant [[Terminal verification results]] bit is "Service not allowed".<ref name=VisaTAC>{{cite web
|title=Visa technology partner: Terminal Action Code (VISA Minimum)
|url=https://technologypartner.visa.com/Download.aspx/id=395}}</ref>