Identity and points. The serial number and probe on the certificate must match the instrument in your inventory; a certificate for another instrument proves nothing about yours, even if it lists the right range. An instrument is verified only at the points where it was calibrated: measuring at -18 °C with an instrument calibrated at 0 °C alone means working in an unverified region.
Deviation, uncertainty and the alarm limit. The deviation is how far the instrument reads from the reference and can be applied as a correction. The measurement uncertainty is the confidence interval around the result and pulls the acceptance limit inward: with an upper limit of 8 °C and an uncertainty of 0.5 °C, the alarm goes at 7.5 °C. ILAC G8 calls this margin a guard band; when it equals the uncertainty, the probability of a false accept drops below 2.5 percent. The traceability line shows the reference rests on a measurement standard.
The recalibration interval is set by the operation; ILAC G24 lists risk, intensity of use and drift seen at earlier calibrations as the criteria. If the drift is accelerating, the interval is shortened or the instrument replaced.
