A characterizational clause is an °equational clause in which the °topic is a °value nominal and the °comment is a °variable nominal.
The definition is from Haspelmath (2025: 17). An example is "Warsaw is the capital of Poland". Characterizational clauses contrast with specificational clauses, where the topic is a variable nominal and the comment is a value nominal (e.g. "The capital of Poland is Warsaw"); see Haspelmath (2025: §9). The term "characterizational" is used in this way by Kuno & Wongkhomthong (1981) and Hengeveld (1992: 82-83).