It seems clear that they're trying to communicate confidence level, for which a boolean would be insufficient. But I can't see why it couldn't have been a % val

It seems clear that they're trying to communicate confidence level, for which a boolean would be insufficient. But I can't see why it couldn't have been a % value in that case. I thought it might be that each value is specified to correspond to some specific confidence, but the spec. is extremely and deliberately vague, which makes the whole thing even more useless as that will inevitably just lead to different implementers returning inconsistent values for arbitrary confidences.