A document is only useful once it becomes a field somebody can check.
Certificates, inspection reports, leases, invoices and surveys are read into typed values that the property register already defines — each quoting the sentence it came from, each waiting for a person.
Every property organisation holds tens of thousands of documents and can answer almost no question from them. Search finds the file; it does not tell you the expiry date, the asset it covers or whether the finding inside it was ever closed.
Residention turns documents into records. Extraction is bound to the dictionary — only fields the register defines — and every proposed value is quoted, typed and adjudicated before it becomes a fact.