The depth cueing only works in preview modes. It's intended as a visual cue to situate objects in world space. It's not a volumetric fog. That's why my curiousity is piqued. We can "render" out preview modes with depth cueing on for stills or animations, but neither the FireFly nor the base P4 renderer support this, actually, this preview render is merely the preview being converted into a frame or still. It's not a typo, but a clarification of what preview options are not handled in "P4 or FireFly renderings"