ntcan DEPRECATED

        
            status.i2.v = NTCAN( reqid.i2.r )
            status.i2.v = NET_CANCEL_REQUEST( reqid.i2.r )
        
         reqid    a word containing the request identification of the
                  request to be cancelled.
        
         status   returns ACNET Global Status (sign-extended to 32-bits):
                      =0 for complete success
                      >0 for conditional success and pending
                      <0 for error condition (in upper byte)
        
         The error codes returned are:
        
            -21 = not connected to network
            -22 = missing argument(s)
            -24 = no such request for process or not a request id
            -47 = network error #2: no address of request id word or not
                                    owner of request control block