Causal Beta Zero

As part of the causal forecasting process, the average sales of non-promo periods in history are divided by the Beta Scale. If the resulting ratio is less than beta zero, the causal forecasting method succeeds. If not, the causal forecasting method fails and the Fallback Method is used to generate the forecast for the time series

Hello,

I would like to know what is the valeu of the beta zero or how it is calculated, because in the documentation it is mentioned but there is no info related of what is this value and how it is calculated. The beta scale parameter I´ve already verified and is defined in the workbook.