Documentation for Namespaces Below Xamarin.Forms

Looking at the API Documentation for Xamarin.Forms, I see the following three namespaces:

Xamarin.Forms.Core
Xamarin.Forms.Maps
Xamarin.Forms.Xaml

I can't find the documentation for classes that are in namespaces such as:

Xamarin.Forms.Platform.iOS.FormsApplicationDelegate
Xamarin.Forms.Platform.Android.FormsApplicationActivity

Is this documentation available?