Degree of start-stop distortion

In telecommunications, the term degree of start-stop distortion has the following meanings: In asynchronous serial communication data transmission, the ratio of (a) the absolute value of the maximum measured difference between the actual and theoretical intervals separating any significant instant of modulation (or demodulation) from the significant instant of the start element immediately preceding it to (b) the unit interval. The highest absolute value of individual distortion affecting the significant instants of a start-stop modulation.

Source: Wikipedia — Degree of start-stop distortion (CC BY-SA 4.0)