Fiducial point

{
  "id": "MLC-T-MET-005558",
  "term": "Fiducial point",
  "field": "Meteorology and atmospheric science",
  "definition": "A fixed reference point or mark on an instrument used as a basis for measurement or calibration. In meteorology, these marks are used on devices like barometers or thermometers to provide a stable, known value against which readings are taken or adjustments are made. For example, the zero point on the scale of a mercury barometer is a fiducial point that must be accurately set relative to the mercury level in the cistern.",
  "url": "https://mlchart.com/terminology/meteorology/fiducial-point/"
}