This part of ISO 27145 defnes the implementation of a subset of unifed diagnostic services (UDS) specifed in ISO 14229-1. The diagnostic services are used to communicate the diagnostic data defned in ISO 27145-2.The subset of unifed diagnostic services derives from the requirements stated in the WWH-OBD GTR (Global technical regulation No. 5; see Reference [17]). The common message set defned in this part of ISO 27145 is independent of the underlying transport, network, data link and physical layer. This part of ISO 27145 does not specify any requirements for the in-vehicle network architecture.This part of ISO 27145 is compatible with ISO 14229-1 and includes provisions to support the data set of SAE J1979-DA and SAE J2012-DA WWH-OBD.This part of ISO 27145 is intended for use with ISO 27145-4, which is the entry point for the protocol initialization and is based on two different data links:- Diagnostic communication over Controller Area Network (DoCAN), ISO 15765-1, ISO 15765-2, ISO 15765-4;- Diagnostic communication over Internet Protocol (DoIP), ISO 13400 (all parts).Due to the usage of standard network layer protocols, future extensions to optional physical layers (e.g. wireless) are possible.Based on the results of the initialization, the external test equipment determines which protocol and diagnostic services are supported by the vehicle’s emissions-related system, i.e.- legislated OBD: ISO 15031 (all parts);- legislated WWH-OBD: ISO 27145 (all parts).