Ecommerce receipts must include the Authorization Code and Transaction Type, Purchase or Credit to protect merchants from chargebacks as a result of customer disputes, per the 2011 chargeback management guidelines for Visa merchants.
When a merchant cannot produce a receipt per the guidelines, the consumer will normally automatically win any dispute*, resulting in a chargeback to the merchant. This presents significant risk to ecommerce store owners.
Receipt requirements are different for card present, thus the requirement to state the URL where the transaction occured. If a merchant submits an ecommerce transaction on a merchant account without the ECI indicator (ie a retail or MOTO account) this is another way merchants can automatically lose disputes.
Search “ECI” in the PDF for related ecommerce items. Customers cannot reverse transactions, they can only dispute them and the bank can reverse pending investigation.
Because the auth code is dynamically generated, this is a function of the shopping cart application and gateway.
* Although the Visa document contains “guidelines” merchants affirm that in their experience, it’s hard to win any dispute that does not meet all guidelines.