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.In Figure 1 the conceptual architecture model is shown for AVI transactions between “On-board Equipment” and “Fixed Equipment”. The air interface concerns the reference point DELTA in ISO 14814.