Sondern or Sundern was a type of land segregation in the Middle Ages in Germany, especially in North Rhine-Westphalia. It gave personal entitlement to farm specific areas of land without owning the land. A Königssondern (royal sondern) is land whose use was administered by the Crown. The term is still found in many place names, indicating the history of the locality.
References
Sondern (land division) Wikipedia(Text) CC BY-SA