taken from the internet,it seems to match all other sources ive read...
INSURANCE CATAGORIES
CAT A
Vehicles that have to be completely destroyed.
CAT B
Vehicles that can be sourced for spare parts but the body shell has to be completely destroyed.
CAT C
Vehicles written-off as costs of repairs are more than the value of the vehicle , but can still be repaired and returned to the road.
CAT D
Vehicles written-off where costs of repairs are less than the value of the vehicle.
CAT X
Vehicles that are not recorded as damage vehicles usually sustaining very light damage if any. Usually relatively new or stolen recovered vehicles.