You can define threshold and distance values to configure confidence levels for validation.
The engine uses the threshold value at the evaluation step to decide if the extraction is successful. If the weight of the best candidate is less than threshold/100, extraction fails and no value is extracted.
The engine uses the distance value at the validation step to decide the validity of an extracted value. If the difference between the best and the second best candidates is less than distance/100, the extracted value is considered invalid, and displays in red in Verifier.