This document describes the data exchange and communications for meters and remote reading of meters in a generic way. It is part 1 of the EN 13757 Standard. Additional parts are: EN 13757 Part 2: Physical and link layer, twisted pair baseband (M-bus); EN 13757 Part 3: Dedicated application layer (M-bus); EN 13757 Part 4: Wireless meter readout. The main use of Part 1 is to provide a protocol specification for the Application Layer for meters. Remark: Electricity meters are not covered with this standard, as the standardisation of remote readout of electricity meters is a task for IEC/CENELEC.