This deliverable reports the work done within WP4, comprising Tasks 4.1, 4.2, 4.3, 4.4 and 4.5 during the initial 18 months, i.e. period 1 of the project, assessing it and planning the related activities for the second period, i.e. months 19-36. The document is structured according to the activities carried out by the work package. After an overall presentation of the main aims of WP4 in Chapter 2, Chapter 3 provides an overview of the conceptual model being developed in ARIADNEplus and its various components. It focuses on the new AO-Cat model, designed to describe the datasets in the Catalogue and improves the previous ACDM model developed in ARIADNE. The full AO-Cat ontology is provided in the Appendix of this deliverable. The chapter al...