{HEAD ~ The pair} of flanges and the pair of webs form {TAIL ~ a closed sectional part} 
{ HEAD ~ The pair } of flanges and the pair of webs form { TAIL ~ a closed sectional part }
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL