A duonominal clause (a cover term) is a °classificational or an °equational clause.
The term was first used by Haspelmath (2025: 2). Classificational and equational clauses share the property of putting two nominals in correspondence, without any possessional or locational meaning. They are often treated together, and often called called "equative" (or simply "predicate nominal clauses"; Dixon (2010) uses "identity clause"). The problem for an intensional definition is that equational and classificational clauses can be semantically rather different (only the latter are always predicating).