Console HDR command 'cal' demonstration
I'm not sure what exact function it performs, here's what the help screen blurb says:
ClearAdaptedLight (cal): Clears the HDR adapted light texture
It seems to "reset" the eye adaptive brightness, showing what it should have been before being set to X due to environmental considerations. It's useful for differentiating between whether things are bright and dark because of shading, or because the base brightness has been changed.