{TAIL ~ A block placement generator} arranges sets of the interface objects into {HEAD ~ block configurations} within the interface 
{ TAIL ~ A block placement generator } arranges sets of the interface objects into { HEAD ~ block configurations } within the interface
TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH