Deepen beneficial ownership and registry identifier research; resolve canon questions

Add source notes on FinCEN CDD/BOI beneficial ownership and ISO 6523/ALEI
registry identifier subtypes. Resolve OpenQuestions: Beneficial Ownership
Relationship as dedicated type; Registry Identifier and Proxy Commercial
Identifier as Reference layer specializations. Update glossary, conceptual
model, terminology, downstream recommendations, and corpus index.

model/ConceptualModel.md

@@ -37,6 +37,12 @@ collapsing into `user`, `group`, or `tenant`.
 ### Reference Layer
 
 - Identifier: value or reference within a scope.
+- Registry Identifier: organization identifier from a registered scheme with
+  known authority, jurisdiction, and optional renewal lifecycle (LEI, UEI, company
+  reg, ALEI, VAT). ISO/IEC 6523 ICD + organization identifier is the preferred
+  interchange encoding.
+- Proxy Commercial Identifier: Registry Identifier with commercial-proxy
+  authority (e.g., DUNS).
 - Scoped Identifier: identifier designed for limited correlation.
 - Credential: proof or control material.
 - Claim: statement made by a source or issuer.
@@ -78,8 +84,9 @@ Core relationship classes:
 - Trust: actor, issuer, verifier, or system relies on another for a purpose.
 - Commercial: vendor actor provides services to customer actor; may reference a
   Commercial Record and one or more Commercial Commitments.
-- Ownership (beneficial): natural person owns or controls organization customer
-  (KYC beneficial owner pattern).
+- Beneficial Ownership: natural person is a regulated beneficial owner of a legal
+  entity or organization customer (KYC/CDD/BOI). Carries ownership_prong and
+  control_prong metadata; distinct from corporate parent Ownership.
 - Synonymity: records or identifiers are asserted to refer to the same target
   under stated evidence and scope.
 
@@ -203,7 +210,9 @@ revocation/supersession path via `Lifecycle State`.
 
 `Organization` actor → `Legal Entity` relationship or specialization → one or
 more `Tenant` scopes → `Representation Relationship` for authorized persons or
-agents.
+agents → `Registry Identifier`(s) (LEI, company reg, UEI) with renewal lifecycle
+→ optional `Beneficial Ownership Relationship`(s) to `Natural Person`(s) when
+KYC/CDD applies → cross-registry `Synonymity Assertion` when multiple IDs exist.
 
 ## Commercial Binding Gradient
 
@@ -223,8 +232,7 @@ No scenario requires glossary or principle changes that the current model
 cannot satisfy. Remaining ambiguities are documented in `OpenQuestions.md`:
 
 - mandatory Synonymity Assertion field set;
-- Realm vs. Tenant promotion for Keycloak-heavy mappings;
-- Beneficial Owner as dedicated relationship type vs. Ownership subtype.
+- Realm vs. Tenant promotion for Keycloak-heavy mappings.
 
 ## Invariants