The vertical advancing seat is provided with a slide block capable of sliding along the vertical advancing seat in {HEAD ~ the vertical direction} relative to {TAIL ~ the base} 
relative to
The vertical advancing seat is provided with a slide block capable of sliding along the vertical advancing seat in { HEAD ~ the vertical direction } relative to { TAIL ~ the base }
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 REL TAIL TAIL TAIL TAIL TAIL TAIL