Key numbers are listed on the back of driving licences in credit card format. They indicate additional information, conditions and restrictions of the driving licence.
The number 174, for example, gives road users an additional permit that younger drivers no longer have today. A three-digit key number is only valid within Germany, while two-digit numbers are valid throughout the EU.. The meaning of the key number 70 is relevant for anyone who has a foreign residence in Germany and a foreign driver's addition, according to the ADAC.