The organizational discipline of centralized control over entity schema updates — ensuring all changes to entity representations are coordinated, versioned, and propagated consistently. Schema governance prevents schema incoherence from distributed, uncoordinated updates. Schema governance includes: centralized schema registry, change approval process, propagation checklist (update website, Wikidata, directories simultaneously), version control, and coherence testing. Without schema governance, well-intentioned updates fragment entity signals: marketing updates the website schema, PR updates Wikidata, sales updates Crunchbase, none coordinate — result is schema incoherence.