I would like to propose as the subject of a discussion in Leipzig the issue related to building the domain ontology for historical settlement units types and administrative (political) units categories, which existed and functioned in European history. We (me and my colleague Tomasz Panecki) could present preliminary scientific (theoretical) and practical output of our project dedicated to this problem in Poland ("Ontological Foundations for Building Historical Geoinformation Systems"). At the Conference of Historical Geographers in Warsaw in 2018 we managed to organize three interesting sessions dedicated to these questions - in a consistent opinion of participants it requires some broader discussion and exchange of experiences. If you are interested in cooperation, please contact:
Bogumił Szady (firstname.lastname@example.org)
Tomasz Panecki (email@example.com).
Some articles and introductory information you can find here.