KML

KML (Keyhole Markup Language) is an XML-based format for storing and displaying geographic data, originally developed for Google Earth. It has been an OGC standard since 2008 and is widely used for placemarks, paths, polygons, overlays, and 3D buildings. Files typically have the extension .kml or .kmz (compressed).

KML supports not only geometry but also styles (colors, icons, line width), timestamps for animation, and embedded images. The coordinate system is WGS84. Because of its simplicity and integration with Google Earth and Google Maps, KML is popular for sharing routes, areas, and points of interest with a broad audience.

KML is often generated by GPS devices, mapping applications, and fieldwork tools. Many GIS packages can import and export KML. For complex analysis or large datasets it is less suitable than e.g. GeoJSON or GML due to XML verbosity and limited support for large feature counts in some viewers.

In web GIS and integrations with PDOK or other Dutch sources, KML is sometimes used as an export option for end users; for machine-to-machine exchange, GeoJSON or GML is often chosen.