COMMONS — The constraint on a classifier that says it must classify something is too restrictive

Classification schemes should be able to be defined without necessarily referring to all of the things that they classify. For example, one should be able to encode industry classifiers without having to know exactly what those classifiers apply to. Thus, the constraint that a classifier classifies some thing should be loosened to be min 0, meaning 'may'.

This issue affects the Classifiers ontology, only

Loosen the restriction on Classifier from at least one to min 0

The original restriction on the property classifies on Classifier was too restrictive, i.e., it required all classifiers to reference at least one thing that they classify. For ontologies that represent things like industry classifiers such as NAICS, the "schema", or t-box, that represents those classifiers should not be required to include them. Typically such reference data would be in a separate controlled vocabulary, or a-box, i.e. a separate ontology that is only imported when in use.

The solution is to change a someValuesFrom owl:Thing restriction to a minCardinality 0 restriction on the property classifies on the class, Classifier.