I the article Foundations of Inference by Knuth and Skilling terms "grade" and "regrade" appear, apparently applied to an $\mathbb{R} \mapsto \mathbb{R}$ function (named $\Theta$ in the article). Basic search on wikipedia/google didn't return much.
So my question is what are the definitions of "regrade" and "grade".
Disclaimer: I'm not native English speaker.