When IFLA defined the concept of Universal Bibliographic Control (UBC) during the 1960s, the objective was to describe all resources published worldwide and split this task internationally by developing tools (such as the ISBD and UNIMARC) for the exchange of descriptive metadata. Today libraries are aiming to build web-oriented catalogues, based on the IFLA LRM model: when the ISBD "resource" is split into the WEMI entities, it seems necessary to adopt a new approach toward UBC and to define new criteria.
The BnF has initiated this process. This paper presents which criteria engage BnF's responsibility as a provider of reference metadata identifying an instance of a WEMI entity or an agent. 

It also presents the quality approach developed by the cataloguing staff in order to reach its objectives and answer the various needs of the metadata users, in a context where the diversity of metadata sources is modifying traditional cataloguing methods. It also investigates the consequences implied by the various stages of the implementation of IFLA LRM by libraries on the exchange of metadata, and concludes with a commitment to maintain the distribution of reusable metadata for all libraries during a period still to be defined.