... to alternatives at the same conceptual level in the hiersrchy, and in msny cases reflect the tra- ditional ides of 'paradigm'. Equations within a variant set are absolute constraints, ... of class definitions. In equs. tions, unification variables have initial capitals, and negation of constants is indicated by ' '. 'kk' is the string concatenation operator ... information in a more specific class. Each equation in a main set functions as an independent constraint, in a msnner which will be clarified below. Variant equation sets, loosely speaking,...