Registration numbers are formatted as LL-DDD-LL (with L denoting a letter and D a digit). The system is sequential and common to all of France. This means that, unlike many other countries, the French system is completely independent of the departments and regions – which is also why drivers can choose between them at will. The very first registration number was AA-001-AA. Initially, numbers were added (up to AA-999-AA), then came the turn of the letters. The system can go all the way up ZZ-999-ZZ. One combination of letters is banned: SS (as it is taken as a reference to the Nazi SS). On top of that, the letters I, O, and U are not used at all because they could be confused with the numbers 1 and 0 and the letter V. Altogether, there are nearly 280 million different combinations. With average annual sales projected at 3 million vehicles, this system could last for up to 80 years.
There are few deviations from the standard French registration number system. Prior to 2009, for example, the police, military, and some government agencies had their own number formatting, but this was abolished when the current system was introduced. Likewise, any French drivers wanting a vanity plate will be left disappointed. Specific combinations of letters are now used only for temporary vehicle registrations (whose numbers begin WW) and on test and demonstration vehicles (in which case the numbers begin with the letter W, followed immediately by a set of digits). What has been preserved, however, is the format of diplomatic number plates, which feature white or orange lettering on a green background.