  The FAIR principles define a number of expected behaviours for the data and
services ecosystem with the goal of improving the findability, accessibility,
interoperability, and reusability of digital objects. A key aspiration of the
principles is that they would lead to a scenario where autonomous computational
agents are capable of performing a ``self-guided exploration of the global data
ecosystem,'' and act properly with the encountered variety of types, formats,
access mechanisms and protocols. The lack of support for some of these expected
behaviours by current information infrastructures such as the internet and the
World Wide Web motivated the emergence, in the last years, of initiatives such
as the FAIR Digital Objects (FDOs) movement. This movement aims at an
infrastructure where digital objects can be exposed and explored according to
the FAIR principles. In this paper, we report the current status of the work
towards an ontology-driven conceptual model for FAIR Digital Objects. The
conceptual model covers aspects of digital objects that are relevant to the
FAIR principles such as the distinction between metadata and the digital object
it describes, the classification of digital objects in terms of both their
informational value and their computational representation format, and the
relation between different types of FAIR Digital Objects.
