ISO 11898-1:2003 specifies the data link layer (DLL) and physical signalling of the controller area network (CAN): a serial communication protocol that supports distributed real-time control and multiplexing for use within road vehicles. While describing the general architecture of CAN in terms of hierarchical layers according to the ISO reference model for open systems interconnection (OSI) established in ISO/IEC 7498-1, it provides the characteristics for setting up an interchange of digital information between modules implementing the CAN DLL -- itself specified according to ISO/IEC 8802-2 and ISO/IEC 8802-3 -- with detailed specification of the logical link control (LLC) sublayer and medium access control (MAC) sublayer.