VDV-ETS

VDV- ETS is the open and secure German standard for electronic fare management systems (EFM) which enables passenger to move freely and easily between public transport companies without having to deal with different tariff zones and ticket machines (interoperability). It provides an open platform which not only allows transport operators to integrate their back office systems as well as those of multimodal and multifunctional partners. The VDV-ETS regulates the cooperation of the various stakeholders in EFM systems at an organizational level (eTicket Germany is the brand name of the VDV ETS).

https://www.vdv.de/