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