Manufacturer and model code
The manufacturer number (HSN) is a four-digit number that identifies the manufacturer of a vehicle.
The combination of the HSN and the three-digit type code number (TSN) consisting of numbers and letters uniquely identifies the type of the vehicle.
For example, the key number 0005/ALQ is the 2007 build version of the BMW 318d Touring with 105 kW (143 hp) and 1,995 cc. Here is 0005 the HSN (for BMW) and ALQ the TSN.
You can find the HSN and TSN of a vehicle in the german "Zulassungsbescheinigung Teil 1" (since 1 October 2005) under 2.1 and 2.2 or in the "Fahrzeugschein" (until 30 September 2005) under 2 and 3.