where α is the angle measured from the horizontal position of the front face (fitted the right way up) of the equipment for which the instrument is calibrated, while β and γ represent respectively the maximum permissible upward and downward deviations from the angle of calibration α.
nuair is ionann α agus an uillinn a thomhaistear ó ionad cothrománach na haghaidhe tosaigh (a fheistítear agus é ag díriú suas i gceart) den trealamh dá bhfuil an ionstraim calabraithe, agus seasann β agus γ faoi seach do na huasdiallais suas agus síos atá ceadaithe ó uillinn an chalabraithe α.