s2_select_authentication_modes – gets sent to informs about starting of S2 flow and propose available authentication modes 
				
					{
     event = "s2_select_authentication_modes",
     modes = { "accessControl", "authenticated", "unauthenticated" }
}
fields type description
event string type of an event
modes table an array of available authentication modes
List of possible authentication modes:
Mode description
accessControl S2 Access Control
authenticated S2 Authenticated
unauthenticated S2 Unauthenticated
s0 S0
clientSide Client-side authentication