There is {HEAD ~ a toothed platen} for locating {TAIL ~ the forcer} so that the forcer is movable over the platen 
There is { HEAD ~ a toothed platen } for locating { TAIL ~ the forcer } so that the forcer is movable over the platen
OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH