An Artex ELT with a part number ending in -999 simply indicates that the unit is not programmed and is intended to be programmed via dongle (DGL-1) or wired into the ELT NAV interface (455-6500). Mostly only fleet operators and airlines request this programming ability to avoid reprogramming an ELT during routine maintenance should the ELT be replaced.
Most Artex ELT systems are received by distributors programmed with the ELT serial number for use in the USA. Thus the P/N ends in -366. If the ELT is programmed for another country, then the appropriate labels are placed on the ELT. However, the original dataplate part number remains the same. Dealer/distributors who are authorized to program Artex ELTs are not permitted to change the part number of the ELT.
Therefore, if someone requires an Artex ELT to actually have the -999 part number then this must be requested before the distributor places the order with the factory. Otherwise, programmed ELTs can be programmed with a default hex address and ID to be equivalent to the -999 status. When this is done by an authorized programming facility, the dataplate remains the same but the separate label with country and three digit code becomes blank and the hex ID label indicates the default hex ID.