The <rpc-reply> element contains the mandatory attribute message-id copied from the corresponding RPC request, along with any additional attributes that are present in the original RPC request.
For those <get> or <get-config> requests that are successfully processed, the response data is encoded as the content of the <rpc-reply> element.
For those <edit-config> or <close-session> requests that are successfully processed, the <ok> element is encoded as the content of the <rpc-reply> element.
For unsuccessful RPC requests, one or more <rpc-error> elements are encoded within the <rpc-reply> element.