{TAIL ~ The edges} of {HEAD ~ the channel} may be provided with flanges 28, 30, similar to the flanges 16, 18 
{ TAIL ~ The edges } of { HEAD ~ the channel } may be provided with flanges 28 , 30 , similar to the flanges 16 , 18
TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH