The merchant can specify the authentication mode that it wants to apply to this transaction with ChallengeInd. Field Description Required Format challengeInd Indicates whether a challenge is requested for this transaction, see values Codes - ChallengeInd No AN2 Version 21 or higher (3DSV2) Data supports a specific authentication process. In the current version of the specification this data element is not defined in detail, however the intention is that for each 3DS Requestor Authentication Method, this field carry data that the ACS can use to verify the authentication process. In future versions of the specification, these details are expected to be included. For Future usage Version 21 or higher (3DSV2) Recommended. Version 21 or higher (3DSV2) Recommended. Version 21 or higher (3DSV2) Mandatory in verifyEnrollment when the buyer is connected to a web browser either within a computer or a mobile (web app integration). Version 21 or higher (3DSV2) Mandatory in verifyEnrollment when the buyer is connected to a mobile application and the merchant is using a 3DS SDK (in app integration). Version 21 or higher (3DSV2) Mandatory in verifyEnrollment. Version 21 or higher (3DSV2) Indicates whether the 3DS Method successfully completed. Mandatory in verifyEnrollment. Version 21 or higher (3DSV2) Preconfigured sizes are width x height in pixels of the window displayed in the Cardholder browser window. Values accepted : Recommended in verifyEnrollment. Version 22 or higher (3DSV2)Condition threeDSReqPriorAuthData No AN2048 threeDSReqPriorAuthMethod Mechanism used by the Cardholder to previously authenticate to the 3DS Requestor, see values Codes - threeDSReqPriorAuthMethod No AN2 threeDSReqPriorAuthTimestamp Date and time in UTC of the prior cardholder authentication No AN16 browser Parameters of the shopper web browser. Conditional Object browser sdk Parameters of the shopper application. Conditional Object sdk threeDSMethodNotificationURL Fully qualified URL where the merchant receive the notification of the completion result of the 3DS Method (server to server notification) Conditional AN255 threeDSMethodResult Conditional AN1 ChallengeWindowSize No N2