The DANS Knowledge Organization Systems Observatory (KOSo) records KOSs within the Social Sciences and Humanities, and the Life Sciences. KOSs have been described and ordered in the observatory through a process of empirical association in order to resist the potential pitfall of already organizing these resources through the lens of other KOSs (e.g. already describing the KOS in terms of existing controlled vocabularies). The KOSo employs both metadata terms and formal classifications, using the Information Coding Classification in a synthetic format together with the KO Literature Classification, thus rendering for each KOS a domain-centric term faceted with a KOS-form term. Additionally, we classify domains using the NARCIS Classification, which is a framework to represent the research foci of the Dutch national research infrastructure.