ODD (Ontology & Data Driven) Principle is the ontology metamodel for building applications based on these methodologies.
The Ontology along with the documentation is published at odd-principle.org.
It builds on three pillar concepts:
A dictionary to define and describe the symbols used in the ontology.
A business process approach to gain flexibility and agility from the ODD-principle.
A methodology to capture and share expert knowledge in a structured way.
Please check out the ODD Principle website for more information.