DAOnt Ontology Enables Machine-Readable Compliance Checking for EU Data Act

A formal ontology called DAOnt has been developed to support compliance with the EU Data Act, which regulates data access and sharing across business-to-consumer, business-to-business, and business-to-government contexts. The ontology reuses elements from three established frameworks—LKIF-Core, ODRL, and DPV—to create machine-readable representations of the regulation's normative structure. It operationalizes three specific articles: Article 4(1) for B2C user access rights, Article 8(6) for B2B trade secret exceptions, and Article 19(2)(a) for B2G competitive use prohibitions. Through SPARQL queries, the system can return obligations, permissions, and prohibitions, allowing organizations to verify whether data sharing agreements align with regulatory requirements. The ontology captures the main concepts and relationships defined in the Data Act, enabling automated reasoning over compliance. This approach facilitates systematic compliance checking by translating legal provisions into computable formats. The work is documented in a paper available on arXiv under identifier 2604.16386v1.