Résumé
A library catalog constitutes a communicational tool which allows access to a collection of documents. It contributes to the circulation of knowledge by signaling and locating informational objects. This referencing consists in deconstructing/reconstructing documents according to principles of standardization: the actualized document is then decomposed into diverse characteristics. With the development of online public access catalog (OPAC), catalogs diffuse their own content beyond the documentary space that they are supposed to represent. Thus the communicational models specific to the bibliographic catalog must be deepened. If a catalog could appear as a documentary showcase, the possibility to comment on documents extends the first goal of the system and also expands the primary document all at once. As a consequence, the catalog has to combine a model of authority with a participative one.