A user-chosen identifier is a resource or request identifier selected by the API consumer instead of generated implicitly by the service. It makes intent explicit, but can complicate creation semantics and should generally be avoided unless the API needs it. section 26.3.1 section 7.3.8
Explicit request deduplication
A create-chat-room request can include an optional requestId. The service can use that client-selected value to recognize an intentional retry, rather than deriving identity from request content. This expresses a deduplication request without silently changing default behavior; expiration means it is not a permanent guarantee against duplicate work. section 26.3.1
Use the pattern deliberately:
- Accept a user-chosen identifier when clients must explicitly identify a request or address a resource. section 26.3.1 section 7.3.8
- Avoid using replace as a create operation unless the API accepts client-selected resource identifiers; otherwise creation and replacement outcomes remain ambiguous. section 7.3.8
