Abstract. The notion of dependency is ubiquitous. This paper approaches this notion from the perspective of digital information preservation. At first, an abstract notion of module and dependency is introduced. Subsequently, and for building preservation information systems, the notion of profile is proposed as a gnomon for deciding representation information adequacy (during input) and intelligibility (during output). Subsequently some general dependency management services for identifying and filling gaps during input and output are described and analyzed (also described as protocols that could be used in the communication between a preservation information system and information consumers and providers).