Base contract type describing a named operation supported by a document or scope. An Operation gives a stable name to a business action, specifies the channel through which requests for that action arrive, and describes the expected request payload shape. Operation is metadata for a supported runtime. It does not execute by itself. A Sequential Workflow Operation or other concrete operation type binds this operation metadata to executable workflow steps. Actor Policy and source policy typically refer to operation names when deciding whether a Timeline Entry or Operation Request may be processed.