{HEAD ~ The walls} of the light trap structure 42 have {TAIL ~ reflective and non reflective interior surfaces} which are indicated at 92, 94, respectively 
have
{ HEAD ~ The walls } of the light trap structure 42 have { TAIL ~ reflective and non reflective interior surfaces } which are indicated at 92 , 94 , respectively
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH