Consolidating SNOMED CT's ontological commitment

SNOMED CT is a clinical terminology that uses logical axioms to provide terms with meaning. This enforces precise agreements about the ontological nature of the entities denoted by the terms, commonly described as ontological commitment. We demonstrate that SNOMED CT implicitly supports at least three different kinds of ontological commitments: i commitments to independently existing entities, ii commitments to representational artifacts and iii commitments to clinical situations. Our analysis shows how the truth-value of a sentence changes according to one of these perspectives. We argue that a clear understanding of to what kind of entities SNOMED CT terms denote is crucial for the proper use and maintenance of SNOMED CT. We argue that the three kinds of commitment can co-exist but need to be clearly distinguished.