{TAIL ~ The rail section} has a profile that provides {HEAD ~ one or more roller contact areas} extending a length of the rail section 
{ TAIL ~ The rail section } has a profile that provides { HEAD ~ one or more roller contact areas } extending a length of the rail section
TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH