Given the challenge of giant knowledge graphs created by major eco-nomic actors, which could virtually replace research in the Humani-ties and Social Sciences (HSS) in responding to public concerns, thequestion arises of how to increase the value of research data throughtheir publication and networking, applying the FAIR principles. Bothan epistemological and a semantic analysis show that the most rel-evant part of research data is factual information, understood as arepresentation of the objects observed by the scientific disciplines,their properties and their relationships.This rich universe of information will be made understandable andtherefore reusable through the application of foundational ontologiesand a methodology based on the distinction between different levelsof abstraction, allowing the collective development of one or moreshared and reusable domain ontologies. This vision is being carriedout around the CIDOC CRM, as core ontology, and Semantic Datafor Humanities and Social Sciences (SDHSS), as a high-level exten-sion of it, as well as an ecosystem of sub-domain extensions that canbe easily managed through the ontome.net application. This willresult in an interoperability that is semantically richer than the sim-ple alignment of ontologies and less costly in terms of resources, andabove all adapted to the scientific and humanistic project of the HSS.