 Let a grade language \(L\) be a strictly ordered collection of expressions, the grades. The grades could be adjectival expressions of a natural language, such as excellent,  good, acceptable, poor and terrible, or they could be characters such as the familiar letter grades of academic evaluation. They could be numerals (then often called scores) or the strings of stars commonly used to evaluate hotels and restaurants. They could be any symbols that come in some fixed order (from “top” to “bottom”).