The service uses standard HTTP return codes - as follows:

• 200 OK - the request has succeeded.
• 400 Bad Request - The server will not process the request due to XML-schema validation error.
• 401 Unauthorized - The request has not been applied because it lacks valid authentication credentials.
• 403 Forbidden - The access is permanently forbidden and tied to the application logic, such as insufficient rights to a resource.
• 500 Internal Server Error - The server encountered an unexpected condition that prevented it from fulfilling the request.
• 503 Service Unavailable - The server is not ready to handle the request. Common causes are a server that is down for maintenance or that is overloaded.

Different implementations might extend the set of return codes.