Secretary) or (Trainee Detective Inspector). Trainee officials of the senior service are called , e.g. for a trainee teacher. They receive a special salary and hold the legal status of , albeit without tenure for life. The trainee period is followed by a probationary period. This period usually lasts three years, occasionally longer. The salary is based on the salary grade which the will hold upon achieving tenure for life. Usually, the designation of office precedes the abbreviation "z. A." (), which means "to be employed", e.g. Again, there is an exception with regard to the senior service, where probationary may be called (e.g. Studienrat z. A., ), or, alternatively, , although this is now less common. The official becomes a , i.e. a with full tenure for life. It should be borne in mind that, whether applicants undergo steps 1, 2, or 3, they are already hold the status of , although initially in training or on probation. It is also important to know, that normally it is impossible to become a after the age of 45. Fields of work The status of Beamter is held by administrative officials, but also by policemen, prison guards, customs officers, most teachers and university professors, and other professionals in the public service, and by certain holders of political offices such as mayors (but not ministers, who have a peculiar, but similar, status governed by public law). For holders of political office, the status of Beamter is not permanent, only applying during the term of office. Furthermore, while most teachers in the Western states of Germany are Beamte, this is not necessarily the case in Eastern states. Berlin, for example, has abolished the status of Beamter for teachers. Formerly, Beamter status used to be bestowed more liberally. As it results in permanent tenure, there are still many Beamte amongst those working for the German post office (Deutsche Post and Deutsche Telekom), the railway services (Deutsche Bahn), and other public utility companies, many of which are either no longer state-owned or have been converted into companies governed by private rather than public law. New employees at those entities are no longer made Beamte. Privatisation and reductions in the number of established posts have reduced the overall number of Beamte. Since 1991, the number of Beamte has declined by 1.4 million to around 3.9 million. This meant that, as of January 2007, reunited Germany had