3.2.5.9.1.1 Receiving an FSCTL_SRV_REQUEST_RESUME_KEY Function Code
If the response indicates that an error occurred, then the client MUST propagate the error to the application that initiated the call.
If the response indicates that the operation is successful, then the client MUST return the copychunk resume key that is received in the Data block of the response to the application that initiated the call.