Simultaneously, {HEAD ~ the fabric} is trimmed adjacent {TAIL ~ the spline cord} in the groove 
is trimmed adjacent
Simultaneously , { HEAD ~ the fabric } is trimmed adjacent { TAIL ~ the spline cord } in the groove
OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH