The older key coding system is on cars 00001 to 08869 (last five digits of VIN) and allows non Jaguar dealers to programme keys.
This is done via the OBD port.
Cars 08870 and onwards, in 2015 JLR changed the system so that the OBD is taken out of the equation for key programming.
The new system has a separate module that will only talk to the two original keys so you can't clone/create any new ones.
If you lose one or require a replacement then you will get stung for two new keys and a new module, of which the last Jaguar quote I can see was £738 for reference only.