The DataServiceId response header is returned by the server when the response payload for an InsertEntity request (section 22.214.171.124.1) or an InsertMediaResource request (section 126.96.36.199.3) is empty. The value of the header is the identifier of the entity that was acted on by the request. The identifier, in this case, is the same identifier that would have been returned in the response payload (for example, as the value of the atom:id element for Atom responses).
The DataServiceId response header is defined by the following grammar.
DataServiceId = "DataServiceId" ":" ( token )
The content of the DataServiceId header MUST be an IRI as defined by [RFC3987].
The DataServiceId header is only meaningful in a response to an InsertEntity request or an InsertMediaResource request with a 204-No Content response. If it is included on any other response or request, the DataServiceId header MUST be ignored.