A method, a device, and a computer program for operating a data processing system, including at least two nodes that are connectable via a data line for transmitting messages. A message includes an identifier for arbitrating messages to be transmitted, the identifier containing—information concerning a priority via which a processing sequence of messages ready for transmission is determined, and the identifier—containing information concerning a network node, via which a sender of the message is unambiguously determined, and—containing information concerning a service, via which a service is determined.