What is the Camera Responsibility Chain ?

I’m trying to understand the Unreal Engine 4 systems.
I was read the Camera document and there was some strange chain system on the camera.
can anyone explain this?
link is here. Cameras in Unreal Engine | Unreal Engine 5.1 Documentation
see the bottom of the document after the View Target section.
Thanks!

It looks like the documentation wasn’t fully carried over from 4.27. This page defines the chain in that version of Unreal: