Fig. 5.

The class diagram of the three levels of DMTO’s main core. DMTO was built as a set of modules. These modules were implemented from scratch or imported from other well-known ontologies. For example, the temporal aspects are imported from the TIME ontology. Building DMTO in layer form supports subsequent maintenance and improvement. The green lines indicate data properties, the blue lines indicate object properties, rectangles are classes, and the black lines are subclass properties