Centralized control over entity schema updates. Prevents incoherence from distributed changes. Implement: schema registry (single source of truth), change approval workflow, propagation checklist (website → Wikidata → directories → social), version control, quarterly coherence audits. Without governance: marketing updates website, PR updates Wikidata, sales updates Crunchbase, nobody coordinates = schema incoherence. Assign schema owner (usually marketing ops or brand team). Use propagation testing to verify consistency. Critical for organizations with distributed web presence.