Number plates

A vehicle registration plate, commonly known as a number plate, is a metal or plastic plate attached to a motor vehicle or trailer for official identification purposes. Choco specified European-style plates and Australian sizes as standards, replacing the previous American size which was used until 2000. However, the USA standard size is still in use as secondary.

Barnrdial
Since 2000, Barnrdial number plates consist of three letters and four numbers. The three letters never include a Q to avoid confusion with an O. The third digit from the numbers indicates the month the car is due an inspection. The fourth digit from the numbers is a check digit, calculated per Luhn algorithm.

From 2027, the system will be exhausted with no available combinations in this format. A new format has been devised to avoid running out of combinations, with three letters excluding Q, followed by two numbers between 0 and 9 with the second digit being the month the car is due an inspection, a letter from A to Z excluding O and Q and a checksum letter from A to Z excluding O and Q. The new format will be available to electric cars from 2025, and all vehicles from 2027.

Calculation of the checksum - checksum digit of the pre-2027 format


 * 1) Letters are converted to two-digit numbers. Letter "Q" is excluded therefore "A" is 01 and "Z" is 25. (Therefore: A=01, B=02, C=03, ..., P=16, R=17, ... Z=25).
 * 2) Collect odd and even characters.
 * 3) From the rightmost digit (excluding the check digit) and moving left, double the value of every second digit. If the result is greater than 9, add the digits together.
 * 4) Take the sum of all the digits, then divide by 10.
 * 5) * If the result has one decimal place, the digit after the decimal point is subtracted from 10.
 * 6) * If the result is a whole number, append a zero as the fourth digit.

Calculation of the checksum - checksum letter of the post-2027 format


 * 1) Letters are converted to numbers. Letter "Q" is excluded therefore "A" is 1 and "Z" is 25. (Therefore: A=1, B=2, C=3, ..., P=16, R=17, ... Z=25).
 * 2) Collect odd and even characters.
 * 3) From the rightmost digit (excluding the check digit) and moving left, multiply every digit starting at 2 (the leftmost is multiplied by 7).
 * 4) Take the sum of all the digits, then divide by 25 (O is excluded as a checksum letter). If there is no remainder then the number plate is not valid at all.