{TAIL ~ The housing} is provided with a slot like {HEAD ~ longitudinal opening} , which on either side is flanked by a housing limb  
{ TAIL ~ The housing } is provided with a slot like { HEAD ~ longitudinal opening } , which on either side is flanked by a housing limb
TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH