I believe you are talking about dies and taps- which have a sort of inward cut Maltese Cross appearance, or cloverlead appearance in the stock, which is placed in a holder- and the job begun.
Mechanically by a fixed reference. One turn of the barrel equals 25 thousandths of an inch- sometimes called 25 mills ( do not confuse with milimeters) therfore it can be read-off by an experienced...
operating thread is nothing but a simple programs or some information is provided in a row where process threads are the which a single sequence stream within a process