The ESA Infrared Space Observatory (ISO) ended its mission in 1998. The so-called Post Operational Phase, during which both the quality of the scientific data and the functionality of the ISO archive were improved, ended in 2006. Meanwhile, the International Virtual Observatory Alliance (IVOA) is coming up with a new standard to enable common characterisation of astronomical data, the Characterisation Data Model. The main aim of it is to define the high level metadata necessary to describe the physical parameter space of the observed, or otherwise simulated, astronomical data (being them images, spectra, etc.), and to allow enhanced interoperability to the astronomers. Given the maturity of the ISO archive on one side, and the new ability to standardise onto typical characteristics of the scientific data products on the other, it has been decided, within the ESAVO effort, to apply the characterisation concepts and standards to the ISO science data. In this paper we will review such process and present how we can now map the well established ISO metadata, stored in the ISO archive databases, to the elements of the characterisation data model, via the ESAVO DMMapper. Such mapping allows queries to be performed without prior knowledge of the internal structure and organisation of the ISO data archive, a big step toward the interoperability of any data centre.