A new numbering scheme had to be introduced in the Transvaal, after the Johannesburg series exceeded the number  TJ 999-999 . An alphanumeric system was introduced in this province, which allowed more permutations with fewer characters. The reason given for this change was that it was necessary because the system was computerised, which was an argument only valid for a few years. Despite this, a trend towards centralisation of vehicle registries continued, despite its inconvenience to motorists. The series comprised three letters followed by three numbers and the letter T. All number plates used black text on a yellow background, for example:  BCD 123 T .