The long-term preservation and access of both digitally born and digitally reformatted resources is a top priority research area for all the custodial institutions. The digital object medium has to be preserved in the same way as analog documents medium, but the technological obsolescence is the major concern for long term preservation and access to the intellectual content. Content and medium migrations and/or technological platform emulation are already applied and experimented. In addition the OAIS (Open Archival Information System) reference model for archiving all object types including digital objects is under ISO international standard processing. All the current library research programs for the definition of the functions and the metadata of a digital object archival system that complements the classical library automated system are building on this model. The objective is to define the standard components of a reliable system on which long term retention and access of digital objects can be guaranteed.