The api property (number) determines which event handling API version is used by the monthly calendar.
DayPilot.Month.api.api=2 by default. In legacy ASP.NET WebForms and ASP.NET MVC integrations, .api=1 is the default.
Supported versions:
.api=1 (legacy, default in ASP.NET WebForms, ASP.NET MVC)
.api=2 (default)