Concepts like "Open Source", "Reciprocal or permissive licence", Compatibility and Interoperability still need to be explained. Each notion has legal impact and understanding what makes a licence unique and what differentiate it from all other licences is important.

A new December 2020 presentation details the implications of the EUPL vision of sharing software based on the clarification of key concepts: Open source, Reciprocity, Compatibility, Interoperability, Compliance with EU law and  support by a strong community on Joinup.eu.