Spanish rectors are chosen from within the body of university full professors ("Catedráticos" in Spanish); it is compulsory for anyone aspiring to become a rector to have been a doctor for at least six years before his election, and to have achieved professor status, holding it in the same university for which he is running. Usually, when running for election, the rector will need to have chosen the vice-rectors ("vicerrectores" in Spanish), who will occupy several sub-offices in the university. Rectors are elected directly by free and secret universal suffrage of all the members of the university, including students, lecturers, readers, researchers, and civil servants. However, the weight of the vote in each academic sector is different: the total student vote usually represents 20% of the whole, no matter how many students there are; the votes of the entire group made up of professors and readers (members of what used to be known as the "Claustro" ("cloister")) usually count for about 40-50% of the total; lecturers, researchers (including Ph.D. students and others) and non-doctoral teachers, about 20% of the total; and the remainder (usually some 5-10%) is left for non-scholarly workers (people in administration, etc.) in the university. Spanish law allows those percentages to be changed according to the situation of each university, or even not to have a direct election system. Indeed, in a few universities the Rector is chosen indirectly; the members of the modern "Claustro" (a sort of electoral college or parliament in which all the above-mentioned groups are represented) is chosen first, and then the Claustro selects the Rector.