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