A method for serial data transfer in a bus system having at least two bus subscribers that exchange messages via the bus, the transmitted messages having a CAN standard ISO 11898-1 structure, where for a first marker (EDL), the control field of the messages, divergently from ISO 11898-1, encompasses more than 6 bits, and for the EDL, the data field of the messages, divergently from ISO 11898-1, may encompass more than 8 bytes, the values of the 4 bits of the data length code being interpreted divergently from ISO 11898-1 to establish the data field size, and for a second marker (BRS), the bit length for at least one predefined or predefinable region within the message assumes a value that is shortened as to the bit length used before the second marker was present, the region beginning at the earliest with the second marker and ending at the latest with the CRC delimiter, and the BRS occurring only when the EDL is present, and occurring in the control field of the messages which encompasses more than 6 bits.