Fig. 1
The X-Ray sample ontology. The light blue icons represent ontology terms, with the prefix (i.e., pmd) indicating the ontology that the term was created in. The dark blue rectangles indicate relationships created between entities. The yellow ovals either indicate the type of the value stored in each subclass or the unit that the value is expressed in, with the prefix indicating the ontology the unit definition belongs to or the schema language that the value type is defined in.
