Method for identifying a reserved data area, and corresponding apparatus

An apparatus for receiving or transmitting data to or from a data area for further functions, said area forming a reserved area when interpreted in accordance with a first specification, said data area for further functions being usable as a header area with at least one bit for a status information item, or being usable at least in part as a useful data area when interpreted in accordance with a second specification, said apparatus comprising:

• means operable in the event of reception for reading said status information item from said header area;
• means for setting said status information item to a first value designating “reserved” whenever said data on said data carrier have been generated or processed in a way which implies that a content of said data area for further functions no longer complies with said second specification;
• means for setting said status information item to a second value designating “valid” whenever said data on said data carrier have been generated or processed in a way which implies that a content of said data area for further functions does comply with said second specification;
• and,
• means operable in the event of transmission for transmitting said status information item together with said header data.

A data carrier, comprising:

• a data area for further functions having reserved areas when interpreted in accordance with a first specification;
• said data area for further functions having a header area comprising a status information item of at least one bit;
• and,
• said status information item indicating whether or not said data area for further functions is usable as a useful data area compliant with a second specification.

A first data carrier programmed in accordance with a routine set of instructions for implementing a method of data processing with a second data carrier, said method comprising the steps of:

• designating at least one data area of said second data carrier for further functions, which can form either a reserved area when interpreted in accordance with a first specification or a useful data area, with a header area for a status information item of at least one bit, when interpreted in accordance with a second specification;
• in the event of reception, reading said status information item from said header area;
• setting said status information item to a first value designating “reserved” whenever said data on said data carrier have been generated or processed in a way which implies that a content of said data area for further functions no longer complies with said second specification;
• setting said status information item to a second value designating “valid” whenever said data on said data carrier have been generated or processed in a way which implies that a content of said data area for further functions does comply with said second specification;
• and,
• in the event of transmission, transmitting said status information item together with said header data.