OPDA Knowledge base
Concept tier foundation

Role

opda:Role

Role

A Role is a part you play — borne by exactly one underlying Kind of party. A Proprietor is a Role borne by a Person (or, under a named specialisation, by an Organisation — but never by both kinds simultaneously).

Why it matters

Roles are the answer to “this party is acting in capacity X for the purposes of this context — but the party is the same party”. A single Person can be a Proprietor on one Title, a Seller in one Transaction, and a Buyer in another — without becoming three different individuals. The Roles are anchored to the contexts (the Title, the two Transactions); the Person identity persists across all of them.

If you are an integrator who has been tempted to “key the Role” (give a Proprietor its own ID independent of the Person it sits on), this is the entity that tells you not to.

Hard cases

  • A Role outlasts its bearer. Cannot happen by construction — a Role borrows identity from its bearer, so when the bearer ceases, so does the Role-instance. (Successor roles get new Role-instances on the successor bearer.)
  • Two Roles, one bearer, one context. A Person is both Proprietor and Seller of the same Property in the same Transaction. Two distinct Role-instances on one Person — they carry different role-specific properties (capacity, evidenced authority) without conflating.
  • Role keyed in error. A downstream system invents a proprietor_id independent of the Person it sits on. The IC says: this is wrong. The Proprietor has no identity qua Proprietor; identity is the Person’s.

Identity Criterion

A Role-instance is identified by its (bearer, context) tuple — the Person (or Organisation) bearing the role, plus the context (Title, Transaction, Proprietorship) it sits in. The Role NEVER supplies its own identity. See the Logical tier → for the typed structure.

  • Role Mixin — the cross-Kind variant: a Role Mixin can be borne by more than one Kind
  • Relator — Roles sit within a Relator’s context
  • Proprietor — the canonical OPDA Role (Person → Proprietor in a Title context)
%%{init: {"theme": "base"}}%% flowchart LR accTitle: Role related-Kinds neighbourhood graph accDescr: Role as the pattern Kind specialised by Proprietor (the canonical OPDA Role); related to RoleMixin (cross-Kind variant) and sitting within a Relator's context. classDef centre fill:#E1BEE7,stroke:#6A1B9A,stroke-width:3px,color:#4A148C classDef cls fill:#B3E5FC,stroke:#0277BD,stroke-width:2px,color:#01579B Role["Role
(pattern)"]:::centre RoleMixin["RoleMixin
(cross-Kind)"]:::cls Relator["Relator"]:::cls Proprietor["Proprietor
(canonical Role)"]:::cls Role -->|"sitsWithin"| Relator Role -.->|"contrast with"| RoleMixin Proprietor -.->|"specialises"| Role

Source ODR

ODR-0006 — Agents and roles §Q2

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