{HEAD ~ This central spindle} can be {TAIL ~ a solid post} or it can be an annular shaft through the center of which a light source can be directed 
be
{ HEAD ~ This central spindle } can be { TAIL ~ a solid post } or it can be an annular shaft through the center of which a light source can be directed
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH