ISO 27145-4:2016 defines the requirements to successfully establish, maintain and terminate communication with a vehicle that implements the requirements of the WWH-OBD GTR (Global technical regulation No. 5; see Reference [16]). This requires plug and play communication capabilities for the vehicle, as well as for any test equipment that intends to establish communication with a vehicle. This part of ISO 27145 details all the OSI layer requirements to achieve this goal.ISO 27145-4:2016 is intended to become the single communication standard for access to information relating to vehicle on-board diagnostics (VOBD). To allow for a smooth migration from the existing communication standards to this future world-wide standardized communication standard, the communication concept as specified in this part of ISO 27145 is based on two different data links:- diagnostic communication over Controller Area Network (DoCAN), ISO 15765-4;- diagnostic communication over Internet Protocol (DoIP), ISO 13400 (all parts).NOTE It is intended that this part of ISO 27145 will be extended as necessary upon introduction of additional communication media.IMPORTANT Use cases deriving from country-specific implementation of GTR No. 5 into local legislation are not included in this part of ISO 27145.