A method for transmitting useful data from a data source to a data sink, the data source being connected to a locating unit, the useful data in the data source being assigned supplementary data derived from information of the locating unit connected to the data source, which are transmitted to the data sink together with the useful data, wherein the received useful data in the data sink are assigned additional supplementary data, which are derived from additional information of a locating unit connected to the data sink. A system for transmitting useful data from a data source to a data sink, the data source being connected to a locating unit and the data source being designed to assign to the useful data supplementary data derived from information of the locating unit connected to the data source and to transmit it to the data sink together with the useful data, wherein the data sink is connected to a locating unit and the data sink is designed to assign to the received useful data additional supplementary data, which are derived from additional information of the locating unit connected to the data sink. When the supplementary data assigned on the source-side and the additional supplementary data assigned on the sink-side are set in relation to each other, information about the data transmission may be obtained therefrom.