Merchants can also choose to include merchant-defined fields to further customize the information included with a transaction. Merchant-defined fields are any fields that are not recognized by the payment gateway as standard application programming interface (API) fields.
For example, the merchant might want to provide a field in which customers provide specific shipping instructions and product color information. All you need to do is submit a custom field name and any accompanying text with the transaction request string—for example, shipping_instructions and product_color.
Note: Standard payment gateway fields that are misspelled are treated as merchant-defined fields.
WARNING: Merchant-Defined Data fields are not intended to and MUST NOT be used to capture personally identifying information. Accordingly, Merchant is prohibited from capturing, obtaining, and/or transmitting any personally identifying information in or via the Merchant-Defined Data fields. Personally identifying information includes, but is not limited to, name, address, credit card number, social security number, driver's license number, state-issued identification number, passport number, and card verification numbers (CVV, CVC2, CVV2, CID, CVN). In the event that Authorize.Net, a CyberSource solution, discovers that Merchant is capturing and/or transmitting personally identifying information via the Merchant-Defined Data fields, whether or not intentionally, CyberSource WILL immediately suspend Merchant's account, which will result in a rejection of any and all transaction requests submitted by Merchant after the point of suspension.