OPAL2026: Editor's Preface

This volume contains the accepted papers presented at OPAL2026: 2nd Workshop on "ODRL and Beyond: Practical Applications and Challenges for Policy-Base Access and Usage Control" held on May 11, 2026 in Dubrovnik. This volume formally constitutes the proceedings of the second edition of the workshop, but it is in fact the ninth time the ODRL academic community has convened: the first workshop took place in Vienna in April 2004, three years after the original XML-based ODRL 1.0 specification appeared. A W3C Recommendation for ODRL 2.2, built on OWL, followed in 2018, representing a significant semantic leap, but leaving the authorization of policies outside its scope. Since then, new industries, new regulatory frameworks and new data-sharing architectures have significantly raised the stakes. The community is now actively discussing ODRL 3.0, and the contributions in this volume will substantially shape what the next version will look like. The broader context is worth naming. In a world dominated by large language models and probabilistic reasoning, the certainty that RDF and symbolic logic provide when authorizing access to data becomes more valuable, not less. It is not by chance that this workshop is co-located with the Extended Semantic Web Conference (ESWC), one of the most notable venues for research on knowledge representation and semantic technologies.

This edition of the OPAL Workshop received 15 submissions and accepted 9. The use case paper by Fischeidl and Hefele opens the program with an application to archival collections. The regular papers then cover a wide arc: extracting ODRL policies from business process models; adaptive agent negotiation under incomplete information; a use-case analysis of ODRL 2.2 gaps pointing directly toward version 3.0; the CORAL-AC benchmark dataset for linked access control; contractual risk detection using DPV; policy-driven negotiation with Verifiable Credentials; ODRL policy chains for the Data Governance Act's altruism and intermediation frameworks; and a privacy monitoring framework for decentralized environments.

Acknowledgements

We would like to thank the members of the Programme Committee for their valuable comments on the contributions in this volume.

We would like to thank the authors, the ESWC 2026 organization for hosting us in Dubrovnik, and EasyChair for providing the platform for managing the workshop.

We would like to thank the research projects that have supported the organisation of this workshop. The GUIA project funded by the Madrid Government (Comunidad de Madrid-Spain) under the Multiannual Agreement 2023-2026 with Universidad Politécnica de Madrid in the Line A, Emerging PhD researchers (M230020126A-AJCA); the HARNESS, funded from the EU’s Horizon Europe research and innovation programme under grant agreement no. 101169409. The MALTA PID2024-159504OB-I00 funded by MICIU/ AEI/10.13039/ 501100011033. The COST Action CA23147 GOBLIN — Global Network on Large-Scale, Cross-domain and Multilingual Open Knowledge Graphs (https://goblin-cost.eu), supported by COST (European Cooperation in Science and Technology, https://www.cost.eu). The INESData project (Infrastructure for the Research of Distributed Data Spaces in UPM), a project funded in the context of the UNICO I+D CLOUD call of the Ministry for Digital Transformation and Public Administration in the framework of the PRTR funded by the European Union (NextGenerationEU).