NI number plates display up to 3 letters at the beginning. This is to denote the area in which the registration was originally assigned to. As time went on, registrations were given a number that followed these letters. From a single digit, right up to figures that are a combination of 4 numbers like ‘4459’. This, and the addition of ‘I’s being displayed as the letter ‘i’ as well as ‘1’s make this style registration very unique.