OntoClean is a methodology for validating the ontological adequacy of taxonomic relationships. It is based on highly general ontological notions drawn from philosophy, like essence, identity, and unity, which are used to characterize relevant aspects of the intended meaning of the properties, classes, and relations that make up an ontology. These aspects are represented by formal metaproperties, which impose several constraints on the taxonomic structure of an ontology. The analysis of these constraints helps in evaluating and validating the choices made.

Reference:

• the Ontolog invited talk by Dr. Chris Welty - "An Overview of OntoClean" - ConferenceCall_2004_11_18
• An Overview of OntoClean -- a paper co-authored by Nicola Guarino and Chris Welty
• Specific information about using the OntoClean methodology with the Protege tool.
• http://ontoworld.org/wiki/Ontoclean
• http://semanticweb.org/wiki/OntoClean_Community_Portal