Abstract
Change is the only constant. The way life evolves with the passage of time, the same way ontology also evolves with time. When new changes come in the domain then these changes are accommodated in ontology by evolving the ontology from one state to another state. Now all the new changes needs to be maintained for not only to provide the undo and redo facility, but also to provide the facilities like: recovering any previous state of ontology, and to visualize the change effects on ontology to make the ontology changes temporally traceable. In this paper a protégé plug-in is presented with major functionalities; maintaining all the ontology changes in Change History Log (CHL) using Change History Ontology (CHO), visualize the change effects on ontology, and reverting ontology to any previous state, and recovering ontology from an inconsistent state to a consistent state.