For French nationals, this ranking is actually part of a government recruitment program: a certain number of seats in civil or military Corps, including elite civil servant Corps such as the Corps des Mines or Corps of Bridges, Waters and Forests, are open to the student body each year. These specific civil servant corps, that provide the top managers of public administration, are only opened to École Polytechnique students (and recently very few students from Ecole Normale Supérieure). At some point during their course of study, students specify a list of Corps that they would like to enter in order of preference, and they are enrolled into the highest one according to their ranking. The next stepping stone for these French graduates in Polytechnique, or "polytechniciens", on this path is to enter one of four technical civil service training schools: the École des mines, the École des ponts et chaussées, the Télécom ParisTech, the ENSTA Paris or the ENSAE, thus joining one of the civil service bodies known as the "grands corps techniques de l'État". Those who pursue this path are known as X-Mines, X-Ponts, X-Télécoms and X-INSEE, respectively, with the X prefix, for École Polytechnique, identifying them as the most particularly top qualified elite members of Corps among all other graduates of the École Polytechnique.