A complex software setting relationship (a parabola) between electrical signal response on the detector at the end of the sample chamber v. the traceable (alleged) reference alcohol standards used at the factory or Canadian Authorized Service Centre (or by a local police officer) sometime after the instrument hardware comes off the factory line. The calibration curve is different on each individual instrument and changes every time that instrument is re-calibrated. Although the parabola won't change between re-calibrations, the electronic response at the end of the detector can change, resulting in the ideal (what should be the current calibration curve) parabola shifting up, down, sideways, or rotating about an axis (that could be close to 100). Note that the relationship (the parabola) has an infinite number of data points, not just 100.