The military ranks of the Swiss Army have changed little over the centuries, except for the introduction, in 2001, of a new set of warrant officers. The rank insignia for all personnel are worn on shoulder boards with the appropriate background colour (see below). The exception is that, in all services, rank insignia is not worn by recruits; it is however worn by privates once they have finished recruit school. Designations are given here in German, French, Italian and Romansh (in this order), with an English translation which is used during overseas missions. In the chart below, NATO codes are used for comparison purposes only; Switzerland is not a member of NATO, and the rank structure in the senior officer region can be seen to diverge significantly from other armies'.