Step-FitFunc
Piecewise constant function with two segments.
Number: 3
Names: A, B, x1
Meanings: A = Level of the first piece, B = Level of the second piece, x1 = Jump point
Lower Bounds: none
Upper Bounds: none
nlf_Step(x,A,B,x1)
FITFUNC/Step.FDF
Waveform, Baseline