{HEAD ~ The main optical housing} 56 includes {TAIL ~ a viewing aperture} 68 serving as an entrance pupil region to enable light from the object being viewed to pass into the reflecting assemblies of the optical system 
includes
{ HEAD ~ The main optical housing } 56 includes { TAIL ~ a viewing aperture } 68 serving as an entrance pupil region to enable light from the object being viewed to pass into the reflecting assemblies of the optical system
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH