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The above noted transaction types are implemented using one of two modes. One of these modes has two forms in which it can operate, creating three distinct modes, though they are not named this way in the specification.
;Mode1: This is the mode for normal monetary transactions such as an online purchase through a merchant. A transaction value and currency are included in the computation of the cryptogram. If the card does not require it or the terminal does not support it, then both amount and currency are set to zero.
;Mode2: This mode may be useful for authenticating a user in which no transaction is taking place, such as logging into an Internet banking system. No transaction value, currency, or other data are included, making these responses very easy to precompute or reuse.{{paragraph break}}{{glossary}}{{term|With transaction data signing (TDS)}}{{defn|This mode may be used for more complicated transactions, such as a funds transfer between accounts. Multiple data fields pertaining to the transaction are concatenated and then hashed with a Mode2 cryptogram as the key for the hashing algorithm. The resultant hash is used in place of the cryptogram calculated in a non-TDS Mode2 operation.<ref>[http://www.unixgarden.com/index.php/misc/banques-en-ligne-a-la-decouverte-demv-cap Banques en ligne : à la découverte d’EMV-CAP], UnixGarden</ref>}}
Mode1 sounds very much like a specific use of Mode2 with TDS, but there is a critical difference. In Mode1 operation, the transaction data (amount and currency type) are used in the cryptogram calculation in addition to all the values used in Mode2 without TDS, whereas Mode2 includes its transaction data in a successive step rather than including it in the cryptogram calculation step. If it were not for this difference, then all operations could be generalized as a single operation with varying optional transaction data.
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