=Chapter 4 Energy Suppliers / Retailers=
[[File:TAF.png|thumb|Tarif-Anwendungsfälle (TAF)]]
The market role "Lieferant" (retailer or supplier) is the consumers contracting party for energy delivery. This party is not necessarily the same organization or company acting in the role of grid or smart meter operator. Nevertheless it has vital interest to influence the behaviour of energy deliver to the customer via the smart meter. For this purpose the retailer is using the role of "external market participant" in the WAN connected to the smart meter gateway. The messages from the retailer can be authenticated by the smart meter gateway using the PKI and do include meter readouts (UTILMD 13017), status information and changes in tarriffs.