1 Scope and Application . . This part of the test specification defines the requirements for the serial interface used for data transmission between the electronic components and the external tester system. The physical layer and the data link layer with 200 Baud initialization of the interface is defined in this document. The content of this part of the test specification is mostly identical to part 3 of this test specification. using a higher baud rate for the transmission of the ECU address by the tester the initialization procedure may be reduced significantly. Clauses identical to part 3 of this test specification are marked by references to this part.