All REST API methods return a standard HTTP status code, both in the HTTP header and in the JSON response payload if present.  Generally, when a method results in the successful creation of a URI-addressable object, such as a media ID, a status code of CREATED is returned.  In general, when an asynchronous request is accepted for processing, but not yet completed, ACCEPTED status is returned.  In such cases, applications that require a final status for the requested operation must poll the API to retrieve it.