This International Standard provides the specifications of: ? common AVI/AEI transaction requirements@ which define the common steps of any AVI/AEI transaction; ? AVI/AEI application interface to standardized wireless protocols (referred to as the ??Air Interface??) supporting the AVI transaction requirements@ so as to enable interoperability. This is an interface standard@ adhering to the open systems interconnection (OSI) philosophy (ISO/IEC 7498-1)@ and it is as such not concerned with the implementation choices to be realized at either side of the air interface between the ??Fixed Equipment?? and ??OBE