The first advancing seat is provided with {HEAD ~ a slide block} capable of sliding along the first advancing seat in {TAIL ~ a direction} perpendicular the front surface of the base, whereas the horizontal advancing seat is mounted on the slide block of the first advancing seat and is provided with a slide block capable of sliding along the second advancing seat in a direction parallel to the front surface of the base 
capable of sliding in
The first advancing seat is provided with { HEAD ~ a slide block } capable of sliding along the first advancing seat in { TAIL ~ a direction } perpendicular the front surface of the base , whereas the horizontal advancing seat is mounted on the slide block of the first advancing seat and is provided with a slide block capable of sliding along the second advancing seat in a direction parallel to the front surface of the base
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL OTH OTH OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL 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 OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH