 Approval Voting asks voters to express something about their intensity of preference for the candidates by assigning one of two grades: "Approve" or "Don’t Approve". Expanding on this idea, some voting methods assume that there is a fixed set of grades, or a grading language, that voters can assign to each candidate. See Chapters 7 and 8 from Balinksi and Laraki 2010 for examples and a discussion of grading languages (cf. Morreau 2016). 