The CCN has been set up between 1980 and 1983 by gathering the content of 3 existing catalogues : AGAPE, CPI and IPPEC. As a localization means, it depends on the international ISDS file for the awareness of documents, and relies on the collections of 2 200 libraries on information centers for localization. The CCN also contains a directory which gives a list of the centers together with the services presented. The network of the CCN is arranged according to 3 levels (local, regional and national). It follows 2 rules : first, proceedings are decentralized, (which speeds up acquisition and uptodateness); second, supervision is centralized, (which ensures a coherent databank). In 1984, all the participating centers, and then the subscribers, can have a direct access to the CCN.