This part of ISO/TS 17575 defines the format and semantic of the data exchange between a Front End (OBE plus optional proxy) and corresponding Back Ends in autonomous toll regimes. This part of ISO/TS 17575 deals with the definition of the data elements used to report charging details from the Front End to the Back End and to receive data which can be used to re-configure the ongoing process of gathering charge relevant information in the Front End. The constitution of the charge report is dependent on configuration data that are assumed to be present in the Front End. The assembly of charge reports can be configured for each individual toll regime according to local needs. Charge reports generated in accordance with this part of ISO/TS 17575 are consistent with the requirements derived from the current architectural concept favoured in the relevant standardization bodies. NOTE An EFC architecture standard is currently under development and is to be published in ISO 17573. The data defined in this part of ISO/TS 17575 are used to generate charge reports that contain information about the road usage of a vehicle for certain time intervals. The contents of these charge reports might vary between toll regimes. A toll regime comprises a set of rules for charging, including the charged network, the charging principles, the liable vehicles and a definition of the required contents of the charge report. The data defined in this part of ISO/TS 17575 are exchanged using an open definition of a communication stack as defined in ISO/TS 17575-2. The definitions in this part of ISO/TS 17575 comprise: - reporting data, i.e. data for transferring road usage data from Front End to Back End, including a response from the Back End towards the Front End; - contract data, i.e. data for identifying contractually essential entities; - road usage data, i.e. data for reporting the amount of road usage; - account data for managing a payment account; - versioning data; - compliance checking data, i.e. data imported from ISO/TS 12813, which are required in Compliance Checking Communications.