The application protocol between an application entity in the smartcard and an application entity in a service system consists of a sequence of command/response pairs. Working Group 4 of ISO/IEC JTC1/SC 17 is concerned with the specification of inter-industry commands, which shall be used for the construction of smartcard application protocols, and the specification of data elements relevant for application selection. These specifications will form part 4 (Inter-industry commands for interchange) and part 5 (Numbering system and registration procedure for application identifiers) of the ISO/IEC 7816 standard Information technology - Identification cards - Integrated circuit(s) cards with contacts . The current state and functionality of ISO/IEC 7816 part 4 and 5 as well as its use in the smartcard application package STARCOS will be outlined.