Before revision: Mode-S/ADS-B identifies the aircraft uniquely among all in the world, in a similar fashion as a MAC number for an Ethernet card or the International Mobile Equipment Identity (IMEI) of a GSM phone.
After revision: Mode-S/ADS-B identifies the aircraft uniquely among all in the world, in a similar fashion as a MAC address for a network interface controller or the International Mobile Equipment Identity (IMEI) of a GSM phone.