Presents hardware and protocol specifications for local systems, while specifications for a remote system falls within the scope of another document. Covers direct local systems in which the hand-held unit (HHU) is connected to one tariff device only at a time. Prescribes the software and hardware preconditions which permit an exchange of data between an HHU and a tariff device. Coverage includes: definitions, physical properties, character transmission and data transmission protocol. Also includes detailed annexes.