Scene:
Allows you to plug in a Scene node with a camera to parse and track the 3D lights automatically

Matte:
Controls the obscuration matte to blink out lens flare behind objects. Works with a depth input as well (if 3D occlusion is enabled)

Background:
Set background image for use with previewing Flares from the Lens Flare editor options.

Camera (side arrow):
Optional camera input for 3D lens flares