`document_id` (document identity)
document_id (document identity)
document_id is the stable identity of an evidence document. Bookkeeping uses stable document identity to link evidence to invoices, bank transactions, and postings so audit trails remain navigable even if file locations change.
When identity is stable, a reviewer can always traverse from a booking back to the exact evidence document that justified it.
Example values: DOC-2026-000120, DOC-2026-000121.