There are constraints that appear to be designed to prohibit a property value from being a class or any of the subclasses of that class.

For example, there is a none-of constraint on instance of (P31) with prohibited values Historical Monument, classified historical monument, monument historique inscrit, Rijksmonument, and Rijksmonument complex with replacement property heritage designation (P1435). This appears to be an attempt to require the use of heritage designation (P1435) for any class related to historical monument status. But only these five values are prohibited, so any of their subclasses are not actually prohibited.

This leads to two problems. First, there can end up being many prohibited values, making it hard to view the constraint and determine just what it is for. Second, to keep the constraint correct new subclasses need to be added to the constraint, resulting in a maintenance problem.

If instead the none-of constraint admitted the relation (P2309) qualifier, then these property constraints could be improved. Another way to have the same functionality would be to have a negated value type constraint.