ISO/TS 17575 defines the information exchange between the Front End and the Back End in Electronic Fee Collection (EFC) based on autonomous on-board equipment (OBE). ISO/TS 17575-4:2011 defines the functional details and data elements required to operate more than one EFC regime in parallel. The domains of these EFC regimes may or may not overlap. The charge rules of different overlapping EFC regimes may be linked, i.e. they may include rules that an area pricing scheme shall not be charged if an overlapping toll road is used and already paid for.