{HEAD ~ A magnetic structure} is attached to move with the forcer and has {TAIL ~ a periodic configuration} corresponding to the forcer and in magnetic interchange relation to the platen 
has
{ HEAD ~ A magnetic structure } is attached to move with the forcer and has { TAIL ~ a periodic configuration } corresponding to the forcer and in magnetic interchange relation to the platen
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH