Supervisors are intended to visit and supervise the functioning of schools, provide advice to schools and the authority, and perform diverse administrative and pedagogic tasks. However, administrative tasks take up most of their time. Only former school directors are eligible for the post of supervisor, ATP appointments are given only to former teachers. Applications are assessed and posts allocated in each state by the Comisidn Nacional Mixta de Escalaf6n composed of the Secretarfa de Educacidn Publica (SEP) and representatives of the National Union of Education Workers (Sindicato Nacional de Trabajadores de la Educacidn or SNTE). This mechanism is, however, influenced by union and political criteria. Efforts are currently under way to change this process and make it more transparent.