Keysight U1610A Guia Del Usuario página 76

Using the Oscilloscope 3
Preshoot
Preshoot is distortion that precedes a major edge transition expressed as a
percentage of amplitude.
Std Deviation
The standard deviation (σ) of a data collection is the amount that the data varies
from the mean value.
Keysight U1610/20A User's Guide 73