{HEAD ~ a first step} extending above {TAIL ~ the top surface} of said housing and positioned adjacent to said passage 
{ HEAD ~ a first step } extending above { TAIL ~ the top surface } of said housing and positioned adjacent to said passage
HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH