A stable oscillator used for frequency calibration or reference. Note 1: A frequency standard generates a fundamental frequency with a high degree of accuracy and precision. Harmonics of this fundamental frequency are used to provide reference points. Note 2: Frequency standards in a network or facility are sometimes administratively designated as "primary" or "secondary. " The terms "primary" and "secondary," as used in this context, should not be confused with the respective technical meanings of these words in the discipline of precise time and frequency.