ISO/IEC 14908-1:2012 specifies a communication protocol for local area control networks. The protocol provides peer-to-peer communication for networked control and is suitable for implementing both peer-to-peer and master-slave control strategies. ISO/IEC 14908-1:2012 describes services in layers 2 to 7. In the layer 2 (data link layer) specification, it also describes the Medium Access Control (MAC) sublayer interface to the physical layer. The physical layer provides a choice of transmission media. The interface described in ISO/IEC 14908-1:2012 supports multiple transmission media at the physical layer. In the layer 7 specification, it includes a description of the types of messages used by applications to exchange application and network management data.