@startuml

actor "User" as user
participant "Merchant System" as mid
participant "Payment Gateway" as pg
participant "Acquirer System" as acquirer
participant "Issuer ACS \n(Access Control Server)" as issuer

user -> mid: Order with payment method
mid -> pg: Payment request
pg --> mid: 3DS payment: 3DS redirectUrl
mid --> user: Redirect to 3DS redirectUrl
user -> issuer: Verify 
issuer -> pg: 3DS verification result
pg -> acquirer: Authorize payment
acquirer --> pg: Result
pg --> user: Result
user -> mid: Redirect to merchant's Url
mid -> pg: Query payment result (Check)
pg --> mid: Result
mid --> user: Result

@enduml