Lower threshold. The output latches to 0.0 when the input falls strictly below this value.
Upper threshold. The output latches to 1.0 when the input rises strictly above this value. Must be strictly greater than lower.
Latch value held before the first threshold crossing. Must be 0.0 (low), 1.0 (high), or NaN (undefined until the first crossing). Defaults to 0.0, so a signal that starts inside the dead band reads low rather than NaN.
https://screamer.readthedocs.io/en/latest/ for the Python reference and full details.
Hysteresis comparator. Latches 1.0 above the upper threshold, 0.0 below the lower threshold, and retains its previous value in between.