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