Driving licences are controlled and issued by the Driver and Vehicle Licensing Agency, commonly known as DVLA.
The Driving Standards Agency (DSA) was responsible for carrying out theory and practical driving tests. In 2014 DSA merged with the Vehicle and Operator Services Agency (VOSA) to become a single agency called Driving and Vehicle Standards Agency (DVSA).
Both DVLA and DVSA provide information online through the GOV.UK website. They often use terms which you need to understand to appreciate the limitations of your licence, hence the jargon panel below.
Terms of weight and mass referred to in DVLA and vehicle manufacturers, documents can be considered as interchangeable and are referred to in terms of kilogrammes (kg) and tonnes (t), where 1,000kg is equivalent to one tonne. The following are a few terms used by DVLA and some other terms you will come across when considering the practicalities of towing.
Maximum Authorised Mass (MAM) means the maximum total weight that a vehicle or trailer is designed to carry. It is set by the vehicle's manufacturer and includes the vehicle weight and the maximum load it can carry.
Equivalent terms: Gross Vehicle Weight (GVW), Maximum Permissible Weight (MPW), Maximum Gross Weight (MGW), Maximum Technical Permissible Mass (MTPLM) - caravans
Gross trainweight (GTW) is the maximum weight a vehicle can move on the road as stated by the manufacturer. It includes the vehicle's own maximum loaded weight (MAM) and the weight of a trailer and load. Sometimes referred to as Gross Train Mass (GTM)
Unladen Weight (ULW) is the weight of the vehicle when it's not carrying any passengers, goods or other items. It includes the body and all parts normally used by the vehicle on the road, but doesn't include the weight of fuel.
Kerbweight as defined in a European Directive and as most commonly used, is the weight of the vehicle as it leaves the factory with oil and water for normal operation and with its fuel tank 90% full. It also includes a nominal 75kg for driver and small amount of luggage. This definition is not generally used by DVLA, but is commonly used by the Club and others when matching car and caravan.
The above defined weights can most usually be found in the vehicle or caravan handbook, but in most cases the GVW and GTW can be found on a plate or sticker fixed to the vehicle and most commonly found under the bonnet or on a door post. If your tow vehicle does not show a GTW then the vehicle is not suitable for towing. Caravans normally indicate the MTPLM figure on a plate situated by the door.