In the present specification, {HEAD ~ the term operating system} will be employed to refer generally to operating systems of {TAIL ~ this class} 
In the present specification , { HEAD ~ the term operating system } will be employed to refer generally to operating systems of { TAIL ~ this class }
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL