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