Editing Geography Markup Language (section)

===GML and KML===

[[Keyhole Markup Language|KML]], made popular by Google, complements GML. Whereas GML is a language to encode geographic content for any application, by describing a spectrum of application objects and their properties (e.g. bridges, roads, buoys, vehicles etc.), KML is a language for the visualization of geographic information tailored for [[Google Earth]].  KML can be used to render GML content, and GML content can be “styled” using KML for the purposes of presentation.  KML is first and foremost a 3D portrayal transport, not a data exchange transport. As a result of this significant difference in purpose, encoding GML content for portrayal using KML results in significant and unrecoverable loss of structure and identity in the resulting KML. Over 90% of GML's structures (such as, to name a few, metadata, [[coordinate reference system]]s, horizontal and vertical datums, geometric integrity of circles, ellipses, arcs, etc.) cannot be transformed to KML without loss or non-standard encoding. Similarly, due to KML's design as a portrayal transport, encoding KML content in GML will result in significant loss of KML portrayal structures such as regions, level of detail rules, viewing and animation information, as well as styling information and multiscale representation. The ability to portray placemarks at multiple levels of details distinguishes KML from GML, since portrayal is outside the scope of GML.<ref>{{Cite web|url=https://developers.google.com/kml/documentation/kmlreference|title=KML Reference &#124; Keyhole Markup Language|website=Google Developers}}</ref>