The Supplementary vocabulary of Geonames (EKT version) is a collection of geographical terms curated by the EKT, a subset of the Geoname geographic database. The terms of this vocabulary were not included in the main vocabulary (Geonames Vocabulary (EKT Edition) https://www.semantics.gr/authorities/admin/vocabularies/geonames-places-earth/vocabulary-entries?language=en) as they are areas that occupy more than one administrative region (eg rivers that cross two countries, unions of states, historical areas, etc.). It is primarily used to enrich the content aggregated in the SearchCulture.gr National Digital Cultural Content Aggregator. The vocabulary is continously updated and enriched with additional terms on its application. All terms have been linked to the Geonames Vocabulary (ECT edition). You can see as a common hierarchy the two vocabularies here:https://www.semantics.gr/authorities/vocabularies/geonames-places-earth:geonames-supplementary-places