Formally, traceability is a property of the result of a measurement, through an unbroken chain of comparisons each having stated uncertainties.
In practice, traceability means that the reference standard has also been calibrated using an even higher-level standard. The traceability should be an unbroken chain of calibrations so that the highest-level calibration has been done in a National calibration center or equivalent.
So, for example, you may calibrate your process measurement instrument with a portable process calibrator. The portable process calibrator you used, should be calibrated using a more accurate reference calibrator. The reference calibrator should be calibrated with an even higher-level standard or sent out to an accredited or national calibration center for calibration.