a first leg ZMP restraint condition restricts {HEAD ~ the first leg ZMP position} to {TAIL ~ the first leg ZMP permissible area}, 
to
a first leg ZMP restraint condition restricts { HEAD ~ the first leg ZMP position } to { TAIL ~ the first leg ZMP permissible area } ,
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH