This part of ISO 22900 focuses on the description of an object-oriented programming interface. The objective is the ability to implement server applications, used during the design, production and maintenance phase of a vehicle communication system, compatible to each other and thus exchangeable. From a user’s perspective, access and integration of on-board control units is provided by a corresponding application, the communication server and a VCI module for diagnostics. The user is granted access for the handling of control units (ECUs) in vehicles for the diagnostic services.