GVM: Gross Vehicle Mass, the total your vehicle can legally weigh on the road under any circumstances.
GCM: Gross Combined Mass, the total your vehicle and trailer can weigh together under any circumstances. Your GCM is not your GVM plus BTC.
BTC: Braked Towing Capacity, maximum loaded mass of a braked trailer that can be towed by your vehicle under any circumstances.
Pre Rego: Vehicle is brand new and has not yet been registered. Modifications are completed and engineered then the vehicle is registered.
Post Rego: Vehicle is currently registered.