Thus, when a viewer views the exterior of the lamp generally in elevation, the cover selectively displays different designs to the viewer depending on {HEAD ~ the illumination state} of {TAIL ~ the device} 
of
Thus , when a viewer views the exterior of the lamp generally in elevation , the cover selectively displays different designs to the viewer depending on { HEAD ~ the illumination state } of { TAIL ~ the device }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL