**3. Medical service ontology**

In the sections from now, we define the three main components of the representation system of quality indicators: medical service ontology (MSO), objective graphs, and quantifying concepts.

MSO is an ontology consisting of concepts related to medical services. In this section, we define the ontology by defining its concepts and properties1. The ontology has been

<sup>1</sup> In ontology engineering, concepts and properties in an ontology are often called classes and roles, respectively.

developed based on an ontology developing tool called the "Semantic Editor" (Hasida, 2011).
