Frictionless flow
The branch of 3-D Secure where the issuer approves on risk data alone, and the customer never notices a check took place.
In EMV 3DS the merchant sends an AReq carrying far more than a card number: screen size, browser language, time zone, shipping address, how long the account has existed at the merchant, and around a hundred other fields. The issuer's Access Control Server weighs it all and answers with an ARes. If the status is Y, the purchase is authenticated and the flow ends right there. No pop-up, no code, no banking app.
That was the whole point of version 2. The original 3-D Secure put a password box in front of every purchase, and abandonment was bad enough that plenty of merchants preferred eating the fraud. A frictionless approval still earns the liability shift, so the merchant gets the protection without paying for it in lost sales. What share goes frictionless is the issuer's call, which is how merchant data quality suddenly became a revenue topic.