How to set QElapsedTimer :: ClockType TickCounter?

How to read the value of ticks?

Code:

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//timer3.PerformanceCounter;
        //timer3.TickCounter;
        //timer3.ClockType(TickCounter);
        //timer3.QElapsedTimer::TickCounter;
        //timer3.clockType(2);
        timer3.clockType(QElapsedTimer::TickCounter);
        timer3.start();
time=timer3.nsecsElapsed();   // correctly? Why nsecs? How to read ticks?

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