The first advancing seat is provided with a slide block capable of sliding along the first advancing seat in a direction perpendicular {HEAD ~ the front surface} of {TAIL ~ 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 
The first advancing seat is provided with a slide block capable of sliding along the first advancing seat in a direction perpendicular { HEAD ~ the front surface } of { TAIL ~ 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 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 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