Geographic MetaData (GMD) extensible markup language is a component of the XML Schema Implementation of Geographic Information Metadata documented in ISO/TS 19139:2007. GMD includes all the definitions of http://www.isotc211.org/2005/gmd namespace. The root document of this namespace is the file gmd.xsd. This metadataExtension.xsd schema implements the UML conceptual schema defined in A.2.11 of ISO 19115:2003. It contains the implementation of the following classes: MD_ExtendedElementInformation, MD_MetadataExtensionInformation, MD_ObligationCode, MD_DatatypeCode. New metadata element, not found in ISO 19115, which is required to describe geographic data Information describing metadata extensions.