For administrative purposes the 22 regions of France are divided into Departments. The Department is then governed by a Prefecture and the villages or towns in each Department are governed in turn by the local Mairie who reports to the Prefecture. There are (100) one hundred Departments in France including the Departments overseas. Each Department has both a name and a number. The numbers of the individual Departments are in alphabetical order hence the illogical order on the map. The Departments are sometimes listed by a and b for example that of Corsica which in some cases is referred to as 20 and in others as 20a and 20b. The numbers of the Departments also appear in the first two digits of the postal codes, followed by the rest of the numbers signfiying the town or village. This currently follows through in the registration of all vehicles in that relevant Department.