I wonder if it’s like the grading system we use in school? <60% is F for fail, 60% to <70% is D which depending on the class can be barely passing or barely failing. >=70% would be A, B, and C grades which are all usually passing, and A in particular means doing extremely well or perfect (>=90%). I just noticed that that rating scale kind of lines up with the typical American grading scale, maybe that’s just a coincidence