Entity consistency across all platforms. Audit: website schema, Wikidata, LinkedIn, Crunchbase, directories, social. Check core attributes: name, industry, location, founding date, relationships. Inconsistency causes confidence degradation. Build through: comprehensive sameAs linking, schema governance, update propagation protocol. Maintain: when entity attributes change, update all platforms simultaneously. Test quarterly using coherence audit checklist. Common errors: different industry codes, conflicting dates, inconsistent names. Cross-platform coherence is prerequisite for multi-source signal merging. Incoherence is unforced error.