The work of the framers of these Roman Indexes exercised an important influence even in the States in which the papal prohibitions had not been officially published, as the titles collected for them were largely utilised by the makers of the Indexes of Spain, France, and Belgium; and in like manner, the material put into print in Louvain, Paris, and Valladolid formed the basis of certain of the Roman lists. A more authoritative position in regard to the work of censorship was taken by the Papacy through the publication, in 1564, of the Tridentine Index. This Index, as well through its formulation of the rules for censorship, as because of the greater comprehensiveness of its lists, constituted the most authoritative guide that had yet been issued. The Tridentine Index was promulgated, under the authority of pope and of council, throughout all the Catholic States and also in countries in which the Catholic Church, while no longer the ruling power, still possessed followers. It was printed in a long series of editions issued from all the more important publishing centres of Europe; its lists formed the basis of all subsequent Indexes, while its rules were accepted as the guide for future censors and compilers. After the Council of Trent, a wider and more assured recognition was given by churchmen throughout the Catholic world (from which must, curiously enough, be excepted Catholic Spain) to the authority of the Papacy, acting through the Congregation of the Index, to retain the general direction and control of the business of censorship.