Complex sentence: The Object-Centered High-level REference ontology (OCHRE) is an upper ontology (top-level ontology, or foundation ontology), a formal ontological framework whose purpose is to describe very general concepts that are the same across all knowledge domains.
Split into simpler sentences: The Object-Centered High-level REference ontology (OCHRE) is an upper ontology (top-level ontology, or foundation ontology). The purpose of the ontology is to describe very general concepts that are the same across all knowledge domains.