sensors for identifying {HEAD ~ types} of {TAIL ~ the installed optical parts} which have been installed in the main equipment; and 
sensors for identifying { HEAD ~ types } of { TAIL ~ the installed optical parts } which have been installed in the main equipment ; and
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH