My view of the rotator doesn't rotate unless I rotate it. Under the covers, the derotator is turning. I see a rotator that is referenced to the equatorial coordinate system. I'm not sure how else to explain this. If I ask for some PA both the mech and sky angles stay the same all across the sky. It's like it's mounted equatorially. The PlaneWave control system creates this illusion. Maybe the PlaneWave creates an illusion where the mech and sky angles are always equal ([fixed-offset] = 0).