In the Netherlands, a postcode exists of 4 numbers and 2 letters
Obviously the Netherlands being the Netherlands, it’s a madhatter state of affairs.
Basically the 4 numbers tell a certain area or city. But not always… so, poatcodes starting with 30 and 31 can be Rotterdam, the second digits homing it in slightly. The letters are parts of streets.
However, if you use the postcode and house number and it does define an exact building. So, there is a system to the madness.
@Ponderable saidCanada has 6, 3 letters and 3numbers (letter, number, letter, space, number, letter, number). Don’t know the significance.🤔
Germany switched from four to five digits after the unification.
Argument was that 5 is the international standard...