Some recent number plates of Dutch trucks have a gap in the top left part of the 'zero'. Example:

enter image description here
(source: cbr.nl)

I assume this is done to increase readability; I can't think of any other reason. It reminds me of letter stencils but the 'eight' in the photo shows that can't be the case. Dutch number plates never have vowels so it's not important to distinguish the letter 'O' and the 'zero'.

  • 3
    This is a question for the Dutch Department of Motor Vehicles, not UX.SE. Mar 23, 2021 at 1:43

1 Answer 1


While doing some additional research for this question, I found out the answer already, but it's perhaps worth sharing anyway. It turns out my assumption

Dutch number plates never have vowels

was slightly wrong; even though Wikipedia supports that statement:

Nowadays the letters used do not include vowels, so as to avoid profane or obscene language.

it apparently doesn't hold for semi-trailers whose number plates start with the letter O, and the opening is indeed to indicate that it's an O, according to the responsible government organization (link in Dutch, my translation follows):

The letter O in the registration identifier

If the registration identifier contains the letter O, then the letter O on the number plate should be printed with an opening on the upper left side.

As a letter and a number can't appear together in one component (there is always a dash between them), there's no real risk of mistaking an O for a zero.

  • 1
    It reminds of putting diagonal lines through zeros. Which never seemed to spread beyond the world of coding.
    – PhillipW
    Mar 21, 2021 at 16:04
  • It seems strange that the reason to avoid vowels would be for the purpose of avoiding obscene language. Humans are pretty good at filling in the gaps when it comes to words with missing letters.
    – musefan
    Mar 22, 2021 at 13:04

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